Chapter VI. is devoted to the Aurora Borealis, which plays about the

magnetic pole, and is an electrical phenomena of the upper strata of the atmosphere; and Chapter VII. is an attempt to explain the auroral light as “probably produced by the collision of the subsidiary atoms when they are in the act of electro-apposition.”

The pamphlet is said to be a condensed account of the discoveries of the author in matters connected with atmospheric electricity—discoveries which were described in papers handed to the Royal Society, but which that Society did not read. The Royal Society were wise.

LE COUP DE FOUDRE DE L’ILE DU RHIN PRES DE STRASBOURG. PAR M. F. HUGUENY. 4to. Paris. 1869.

(_Abstracted by G. J. Symons, F.R.S._)

A very full account of an accident by ball lightning. The facts are set out as clearly as possible, the authority is given for every statement, and most carefully engraved plans and engravings are given of all the necessary details. It does not bear upon the question of lightning conductors except in that it shows that a discharge of globular lightning traversed a horizontal distance of 919 yards, passed in front, but below the top, of a building which had three good conductors upon it and struck a chestnut tree, which was by no means the highest tree in the locality.

DIRECTIONS FOR CONSTRUCTING LIGHTNING RODS. _From_ “_Essays on Meteorology_,” _by_ PROFESSOR JOSEPH HENRY.

(Smithsonian Miscellaneous Collections. 8vo., 1871.)

(_Abstracted by A. J. Frost_).

1. The rod should consist of round iron, of not less than ¾ of an inch in diameter. A larger size is preferable to a smaller one (ordinary gas pipe may be employed). Other forms of rod, such as flat or twisted, will conduct the lightning, and in most cases answer sufficiently well. They tend, however, to give off lateral sparks from the sharp edges at the moment of the passage of the electricity through them, which might, in some cases, set fire to very combustible materials.

2. It should be throughout its whole length in perfect metallic continuity, either by screwing the parts firmly together or by welding.

3. The rod should be covered with a coating of black paint.

4. It should be terminated above with a single point, the cone of which should be encased with platinum not less than 1/20 inch in thickness.

5. The shorter and more direct the rod is in its course to the earth the better; acute angles should be avoided.

6. It should be fastened to the house by iron eyes, which may be insulated by cylinders of glass; this, however, is not absolutely necessary.

7. The connection to the earth should be as perfect as possible—in cities nothing is better for this purpose than to unite it to the gas or water pipes. When a connection cannot be formed in this way the rod should terminate in a well containing water, or if this is not practicable it should terminate in a plate of iron, or some other metal buried in moist ground. It should, before it descends to the earth, be bent, so as to pass off nearly at right angles to the side of the house, and be buried in a trench, surrounded with powdered charcoal.

8. The rod should, in preference, be placed on the west side of the house, and on chimnies where a current of heated air ascends during the summer season.

9. A single rod may be placed on small houses, and its elevation should be at least half of the distance to which its protection is expected to extend.

10. Metallic roofs should be united with the lightning rods.

11. As a general rule, large masses of metal within the building, particularly those which have perpendicular elevation, ought to be connected with the rod.

ON LIGHTNING AND LIGHTNING CONDUCTORS. BY W. H. PREECE, Mem. Inst. C.E.

(Journal of the Society of Telegraph Engineers, 27 November, 1872.)

(_Abstracted by Prof. T. Hayter Lewis, F.S.A._)

The author refers to the Escurial having been on fire seven times—four of them certainly from lightning; yet no lightning conductor is fixed even now.

The average deaths from lightning in England are eighteen per annum; in France, ninety-five.

From January 1, to July 31, 1872, 9·26 per cent. of instruments, of different forms, used in the telegraph offices, were injured by lightning.

Electricity is force, not matter, and _Current_ is a well-defined term which implies a transference of electricity from one place to another.

Thunderstorms differ only in degree from the phenomena which cause the ordinary snapping sparks from the machine.

In any case there must be two conducting masses in opposite electrical states, separated by a non-conductor or dielectric.

The light is the effect of the discharge, and is simply incandescent matter. It indicates the path of the discharge and nothing more.

Death by lightning is painless.

_Potential_ is that function of electricity which determines its motion from one point to another.

The path of electrical discharge is prepared beforehand by induction.

The particles of air, &c., are in a state of “tottering equilibrium.” A moving ship, a man on horseback may destroy this, and we have a discharge with all the effects of light, heat, and mechanical energy.

It is very doubtful whether thunder-clouds are themselves the sources of electricity, producing thunder and lightning; they are more probably, mere accumulators as the coatings of a Leyden jar.

Clouds have been known to be absent during a discharge.

Moreover, the charge of a Leyden jar exists not in the coatings but in the dielectric separating them.

So the discharge exists in the air and not in the clouds.

Sheet lightning is a mere reflection of forked.

Evidence proves that some such phenomena as ball or globular lightning exists, and an explanation of it has been given by C. Varley.

Discharge is invariably through the line of least resistance. It may be through metals, bricks, trees, animals, and not always in a single track; it is often divided into two, three, or even four lines.

Thus, an electrical discharge in air, is simply a discharge between two electrified conductors, of such different potentials as to break the resistance of the dielectric separating them.

There is nothing hidden, mysterious, or unknown in it.

A ship is a prominent object; generally a conductor, and reduces the line of resistance between the sea (inner coating) and the cloud (exterior coating of the condenser) determining discharge.

Trees, buildings (except tall spires, &c.) are less prominent.

The effects of lightning experienced on telegraph wires, poles, and instruments by direct discharge are less numerous than those by induction, and seldom destructive.

There were only two cases in the past season where line wires (No. 8 iron, diameter 0·170 inch) were absolutely fused.

Accumulation of a charge upon a cloud converts it into a powerful inducing body.

It induces in the wire an opposite electrical state. Discharge takes place. The cloud suddenly loses its coercive power. The wire recovers its neutral condition, and produces a powerful current in opposite direction.

Wires are affected although buried two feet underground. Unprotected poles are often destroyed. In one case, twenty successive poles were so.

Instruments have had their cases burst out, wood-work has been burnt, and the wires of electro-magnets, &c., been fused.

Clouds are not perfect conductors, so do not part with all their discharge at once. There may be several successive discharges.

_Protection._—Sir. W. S. Harris’s system approved.

_Houses._—Unnecessary expense is often incurred in protecting them.

A warm flue, terminating in a metal grate, is a dangerous conductor, as it ends in the room and not in earth: hence so many accidents indoors. A lightning conductor should expose a prominent metallic point, and offer a path of little or no resistance thence to earth.

Hitherto expensive plates or ropes have been used for this. But the author thinks galvanized iron wire ¼ inch diameter amply sufficient for any dwelling house.

Telegraphic poles, protected by lightning conductors of No. 8 wire (½ the above size), have never been injured.

In one case, fifteen per cent. of unprotected poles have been struck.

But no case of damage has occurred for many years since the poles were earth-wired. The cross-arms are often damaged as far as the earth wires, never below.

The author can conceive no case in which ½ inch standard galvanized iron wire is not ample.

The conductor should be solid and continuous from the gilded or platinum point to the ground.

Joints should be well soldered. Chains and linked rods should not be used.

Earth connections should be formed with iron gas- or water-mains, or be several feet in coke, or in a well.

Each conductor should make a separate earth.

All masses of metal in the line of probable discharge are to be connected with conductor.

Conductors should be examined periodically, they should not be insulated, nor be near soft metal gas-pipes, nor bent in acute angles.

The area of protection appears to be that of a cone, whose radius is equal to the height of the conductor.

One conductor is enough for small houses, but each stack of chimneys should have one in connection with the main conductor.

Lead roofs and iron pipes are easily made into protectors for buildings.

Details given for protecting telegraph apparatus.

The telegraph companies abandoned the use of protectors. The Post Office re-introduced them with good results. The Indian telegraph apparatus is protected, and accidents scarcely ever occur.

_Prevention._—Points prevent the accumulation of charges. But with very tall conductors—as to spires—a current results constantly in one direction, producing electrolytic action and destruction of conductor, as proved by one at Llandaff Cathedral.

So earth should be made with large masses of metal, as gas- or water-mains.

Galvanised iron fastenings should not be used to secure copper conductors to buildings, as galvanic action would be set up.

_Appendix._—Letters quoted from Mr. Latimer Clark and Dr. Faraday as to damage to underground wires from lightning.

The _Discussion_ on Mr. Preece’s paper was conducted by Prof. Abel, Capt D. Galton, Mr. G. J. Symons, who referred to Dr. Franklin’s suggestion as to cold fusion, Prof. Ayrton, who entered at length into the system of prevention used with the Indian telegraphs, Sir W. Thomson, and Mr. Latimer Clark.

Mr. Preece replied, more especially alluding to the phenomena of fire balls.

LIGHTNING RODS AND HOW TO CONSTRUCT THEM.——BY JOHN PHIN, C.E. New York. 1873.

(_Abstracted by W. H. Preece, C.E._)

The author is not an electrician nor a patentee, but the Editor of an engineering paper called the _Technologist_. The book is written chiefly to counteract the machinations of a great nuisance in the United States, called the “lightning rod man.” The Author thinks a good rod as important as a fire insurance policy. Every case of injury that he has examined was due to defective rods, or to the absence of them. The lightning rod is an American invention. He mentions several cases of marked immunity from accident due to proper conductors, notably St. Paul’s and the Monument, London; the Cathedral, Geneva; and St. Mark’s, Venice.

The lightning rod should form the path of least resistance, and it may be of iron or of copper. If of iron he prefers a flat bar 1 inch by ¼ inch, weighing 13 ounces per foot, or No. 00 copper, weighing 6½ ounces per foot. He also advocates copper rope.

He thoroughly believes in the conduction through the mass of the metal, and quotes (p. 12) several experiments in support of that view.

He believes in a good earth and in connecting all waterspouts, eaves, gutters, and metal work generally with the earth and with the conductor; he thinks one good rod enough, and sees no reason why lightning rods should not be painted, indeed, thinks it better to do so, for they become less unsightly; he has no faith in points, nor in gilding, or platinising; he recommends instead cast iron caps to chimneys; he discards insulation as absurd, and suggests that rods may be tacked, or stapled, or strapped to buildings, although he prefers staples; recommends strongly that wet earth should be reached, and that as large a metal surface as possible should be exposed to the ground and embedded in coke; he does not like any connections with the gas pipes.

He suggests that iron conductors may be welded or have merely butt joints, but recommends solder with copper, after being bound with fine wire.

He adduces the fact that Mr. Brooks, of Philadelphia, measured the resistance of three rods attached to three buildings that had been damaged, and found the average to be above the resistance of one hundred miles of telegraph wire.

TRAITÉ DES PARATONNERES, &c. PAR A. CALLAUD. Paris. 1874. Royal 8vo.

(_Abstracted by Latimer Clark, C.E._)

This work consists of 171 pages. It commences with a short history of the subject, which occupies the first chapter. The remaining nineteen chapters treat successively of the collecting points and their mode of action; the conducting rods and the methods of attachment to different classes of building, and their connection with the earth, with concluding observations.

The second chapter treats of the height of conductors and the area protected, in which he follows the usual rules, and recommends lofty rods, their office being not only to safeguard the building, but to withdraw electricity silently from the air and thus prevent strokes of lightning or diminish their violence.

In Chapter III., after citing the opinions of many other writers, he strongly advocates protectors furnished with sharp points of platina, or some inoxydisable metal, securely screwed and soldered on to copper rods, and condemns points of iron or copper. Throughout the work he treats cost as a secondary consideration and considers it false economy to spare any expense necessary to ensure the thorough perfection of the whole system.

In Chapters IV., V., and VI. he gives drawings of connections and of various forms of weathercocks.

In Chapter VII. he recommends multiple points, especially in mountainous countries and where storms are prevalent. He also points out that many buildings are naturally protected by the metal roofs and ornaments belonging to them. So long as these are connected with the ground, he prefers that the projecting rod should be of round iron of considerable length and in one piece, and the conducting cable should wind round it as a collar, and be strongly attached to it by set screws and soldering. He does not advise that all the masses of metal within a building should be connected with a conductor, especially if they are in proximity with human beings, but with a well-made conductor he considers it safer to leave them isolated. (Chapter IX.)

For the conductor he recommends Gay Lussac’s construction, viz., a rod of iron about ⅝ inch square, carried by iron supports, or a twisted cable of iron wires having a diameter of ⅝ inch to ¾ inch, well tarred or galvanised, 6 or 8 feet from the soil these are securely united to an iron bar ⅝ inch to 1 inch diameter. If of copper they may be smaller. Has seen rods of copper of ⅜ inch effectually protect churches, but regards this as a minimum size for a length of 80 feet and ¾ inch as a maximum. The single wires of the cords may have a diameter of 1 millimetre; the joints are made by splicing the strands together and soldering them. (He recommends conductors of straw in some cases for country use. Chapter X.)

The conductor is led along the ground in a channel of half drain tiles, surrounded with coke and terminates in a copper grapnel embedded in a basket of coke. (Chapter XIII.)

Chapters XIV., XV., and XVI. gives details of the construction of lightning conductors for tall chimneys, powder magazines, and ships.

In Chapter XVIII. he gives numerous examples of the utility of conductors, and in Chapter XIX. he gives a _resumé_ of his instructions, again insisting on the perfect continuity of the connections and the perfection of all the parts; these instructions are also embodied in a note read before the Academie des Sciences, in 1862, a copy of which is given at page 167 of M. Callaud’s work.

BLITZABLEITER-ANLAGEN. PROF. C. ZENGER’S SYMMETRISCHE BLITZABLEITER. C. Korte and Co., Prague.

(_Abstracted by G. J. Symons, F.R.S._)

This is really a trade circular, but it gives, in a compact form, the considerations which have induced Prof. Zenger to propose his new system, and a description of the mode in which it is carried out. In the first place it may be well to reprint from the _Meteorological Magazine_, Vol. VIII. (1873), page 155, the report of the paper read by Prof. Zenger at the British Association Meeting.

PROF. ZENGER, ON THE ACTION OF SYMMETRICAL CONDUCTORS AND LIGHTNING CONDUCTORS.

Professor Zenger read a paper, on this subject, illustrating it with the well-known experiment in physics of placing two insulated hemispheres of brass plate in contact with another insulated sphere of brass. If the former were charged with electricity and removed from the inner brass sphere, there was found no trace of electricity on its surface. The electricity was shown to be accumulated on the surface of the outer spherical conductor, with equal tension in every point of the surface. Professor Zenger showed that if the outer hemispheres were replaced by two circular wires, no action whatever in the inner conductor was found. He said it was easy to see that this simple experiment might prove useful in regard to the construction of electric apparatus and of lightning conductors to protect buildings, and even whole cities, from the destructive action of atmospheric lightning. He had, therefore, endeavoured to ascertain the effects if any other form of a symmetrically-arranged conductor were used, instead of a circular form. In the first instance, he had tried the parabolic wires joined to the electroscope; next, a rectangular wire with five different openings. If placed exactly in the middle of the rectangular wire, no action was observed; if placed eccentrically, however, there was small but increasing action; and if he placed a needle or another sharp-pointed instrument between the protecting wire and the electroscope, he still better observed the different action produced by placing the electroscope in an eccentrical position. He therefore thought that it was possible by symmetrical wires placed on buildings, or over whole cities, so to procure an entire protection from atmospherical electricity. If the electric clouds should even enter between the objects protected and the protecting wires, their activity would be greatly diminished, for the wires would become immediately charged, and nearly all the electricity accumulated on their surface without any danger to the protected buildings.

Mr. Glaisher, who had taken the chair in the temporary absence of the president, said their thanks were due to Professor Zenger for his communication upon a subject so important. What they wanted to know was the distance at which buildings were protected by a lightning conductor, and Professor Zenger’s assertion that the sections of a globe were as effective as the whole globe itself, would be an important addition to scientific knowledge if proved to be so.

Professor Clerk-Maxwell, who said he had paid some attention to the subject of shielding bodies from electrical action by means of the wire, feared that the form that Professor Zenger had given them would be rather difficult to work out mathematically.

Professor Zenger said that the correspondent of the _Engineer_ newspaper had just informed him that the instrument hut of the Atlantic Telegraph Company at Valencia was protected by wires on the principle he had just mentioned, and the plan of protecting the hut had been devised by Mr. Cromwell Varley.

We now pass on to Messrs. Korte’s paper, which refers entirely to the application of this symmetrical principle to buildings. They begin by claiming that Prof. Zenger’s system is the only one based upon scientific investigations and practical experiments, and that although far better than the primitive arrangements generally adopted it costs no more. They urge that the conductors should be symmetrically arranged, and yet they say that they should lead to the side of the house most exposed to the weather. They recommend that the upper terminal should be a long oval of gilt brass, something like a blunt spear-head, and that, in ordinary cases, a single copper rod of 0·20 inch diameter (_not_ a rope of that size) will be sufficient; it is to be taken through porcelain insulators, and the earth terminal is to be a copper plate nearly ¼ of an inch thick, buried from 6 to 9 feet deep in coke.

PROTECTION OF LIFE AND PROPERTY FROM LIGHTNING. By W. MCGREGOR. Bedford, 1875. 8vo. 43 pages.

(_Abstracted by Latimer Clark, C.E._)

Mr. McGregor does not give any new facts in connection with lightning, but discusses the theory and action of conductors, and quotes numerous opinions from other writers, with practical suggestions and precautions to be observed in fixing conductors.

Among the principal opinions adduced are the following:—

1. Professor Jenkin’s statement, that if a conductor be armed with a point, the electricity passes into the air rapidly in times of excitement by induction, and so equalises the tension of the surrounding atmosphere as to mitigate, or, in some cases, to prevent the discharge of lightning.

2. De la Rive’s observation that a slight break of continuity in a conductor is filled by a succession of brilliant sparks during a storm, though there be no lightning; that blunt points or balls are equally effective when struck, but are more usually accompanied by explosion than by continuous discharge.

3. The opinions of De la Rive, Dr. Mann, and Preece, that a conductor practically protects a conical space—of which the radius is about double the height—and that the conductor should therefore extend to some height above the building.

4. Ganot’s opinions that a conductor should terminate in a point or points, have sufficient sectional area, be thoroughly connected with the earth, and be connected with lateral metallic surfaces of large extent if it passes near them; either iron or copper may be used, and existing rain and water pipes, &c., may be utilised; but the joints should be made carefully and tested. Chimneys with soot act as dangerous conductors, and should therefore be protected.

The author does not give any precise directions as to the best form or size of conductors.

LYNILDENS FARLIGHED I NORGE. BY H. MOHN, Kristiania. 1875.

(_Abstracted by C. Terkelsen._)

The author, having been specially commissioned to enquire into and investigate the danger of lightning in Norway, found that lighthouses, telegraph stations, and other much exposed buildings, which were provided with conductors, did not by far suffer so much as churches, which in the most cases were unprotected.

Out of about 100 churches reported to have been struck by lightning, only three were provided with lightning conductors: on the first, Kongsberg, the conductor was in good order, and the church was comparatively uninjured; the second church, Fossnes, built of wood, had a conductor, but made of zinc wire, which melted, and of course left the church unprotected; on the third, Brónó (struck 17th October, 1872), the wire had rusted, where it joins the earth, and the church was destroyed.

The author gives a full description of the different cases.

Of 100 churches struck by lightning, fifty-six were totally destroyed, and had to be rebuilt; twenty-four of that number were churches built of stone, twenty-nine of wood; the building material of the remaining three is unknown. It would thus appear that stone buildings are almost as much exposed to be damaged by lightning as wooden ones. Of the above-named churches only one can be said to have been saved by a lightning conductor, viz., Kongsberg. In 1820 the lightning struck the church, set fire to a great part of the wood-work, and did other damage. The tower was then covered with sheet iron. In 1852 the lightning struck the tower again, which, however, then was provided with a conductor consisting of two thin copper plates, 2½ inches wide, fastened on the north and south side of the tower, and both beginning with the iron rod, on which the vane is fastened; but this rod did not end in a point, but in a gilt cross. The conductors were carried down the brickwork of the church to the field, and across the market place, and ended in an old water-butt. When the concussion took place one of the lightning conductors was disabled; but no material injury was done to the tower. In 1872, July 16th, the lightning struck a farmhouse about 700 feet from the above-mentioned church; the farmhouse being about thirty feet, and the tower about 150 feet high.

The construction of a lightning conductor ought to be as follows: It consists of the following three chief parts. (1) The receiver; (2) the conductor; (3) the earth connection. The receiver consists of a copper point 8 inches long and ¾ inch thick; which is screwed into an iron rod, 1½ to 2 inches thick. The screw must fit well and the flats of the copper and iron fittings must be well connected and afterwards soldered round the joint to prevent water and air from rusting the iron. There are various ways of fastening the receiver to the building, but the engineer is generally guided by circumstances. The conductor may be made of iron or copper in the shape of rods or wire twisted like rope. If made of iron rods they should be round and ⅝ to ¾ inch thick; if iron wire-rope is used the thickness must be equal to a rod of ¾ inch; if made of copper the rod must be at least ¼ inch thick, or if made of copper wire-rope ⅜ inch. In both cases the conductor is put in metallic connection with the receiver, and then guided into earth.

The earth connection is merely a continuation of the conductor and must be buried as deep as possible in the earth, and reach the water, if it is to be found.

The end which reaches the water may be constructed in various ways, according to circumstances, but it is of the greatest importance that the earth conductor never gets dry. If there is great difficulty in getting at the water, the earth conductor may be constructed in the following manner. It is made of copper, and has joined to it as many branches as are thought necessary. Each branch has rivetted or soldered to it a copper plate 1 or 2 feet square; they are carried as far away from the building as possible, and buried deep into the earth. Besides this there must be laid an extra conductor, perfectly metallically connected with the chief conductor just under the surface of the earth, alongside of it, out from the building, with as many branches, and as long, as possible. This conductor becomes efficient, as soon as the surface of the earth gets wet through rain, which generally falls during a thunderstorm.

LECTURE DELIVERED BEFORE THE SOCIETY OF ARTS, _28th April, 1875_. By R. J. MANN, M.D.

(_Abstracted by E. E. Dymond, F.M.S._)

Draws attention in the first place to certain established principles.

Different powers of various substances for conducting electricity.

Electrical induction.

In dull fine weather the surface of the earth negative, the surrounding air commonly positive, the surface of the sea positive.

How a thunder storm begins, gradually approaching cloud, lightning between it and earth. According to Delisle and Petit, a lightning stroke _may_ extend 9 or 10 miles, but for ordinary circumstances the striking distance varies between 650 and 6,500 feet. The lightning stroke follows the line of least resistance, and invariably falls upon the most prominent conducting substance, and passes through substances affording an easy way and offering small resistance without disturbing their molecular condition; shatters bad conductors; heats, sometimes melts, good but insufficient ones.

Describes the various forms of lightning—flash, diffused, sheet, and ball.

A continuous rod of good conducting metal must be carried from the top of the building to the ground. Describes varying carrying capacities of iron, zinc, or copper; recommends from his experience in South Africa, 42–strand rope of 1/16th inch galvanised iron wire.

The disintegrating energy is mainly expended on the extremities of the conductor.

In Natal he used to enclose the top of the rope in a tube of stout zinc, finished at the top by a gilded ball of wood, and he opened the strands of the wire above it into a brush. The French electricians strongly recommend a cluster of points.

The earth contact must be good and damp. The French system of Callaud described.

Gay Lussac recommended that all large metallic masses should be brought into connection with the conductor, and the conductor not insulated from the building. M. Callaud, on the contrary, adopts insulating supports for the conductor, and condemns the connecting of metals in the building.

The metals used in the construction of the buildings may be utilised as conductors; rain pipes, metal ventilating pipes, but not soft metal gas pipes.

ON THE PROTECTION OF BUILDINGS FROM LIGHTNING. BY PROFESSOR J. CLERK MAXWELL, F.R.S.

(Reprinted from the _Report of the British Association for the Advancement of Science_, 1876.)

Most of those who have given directions for the construction of lightning conductors have paid great attention to the upper and lower extremities of the conductor. They recommend that the upper extremity of the conductor should extend somewhat above the highest part of the building to be protected, and that it should terminate in a sharp point, and that the lower extremity should be carried as far as possible into the conducting strata of the ground, so as to “make” what telegraph engineers call “a good earth.”

The electrical effect of such an arrangement is to _tap_, as it were, the gathering charge, by facilitating a quiet discharge between the atmospheric accumulation and the earth. The erection of the conductor will cause a somewhat greater number of discharges to occur at the place than would have occurred if it had not been erected, but each of these discharges will be smaller than those which would have occurred without the conductor. It is probable, also, that fewer discharges will occur in the region surrounding the conductor. It appears to me that these arrangements are calculated rather for the benefit of the surrounding country, and for the relief of clouds labouring under an accumulation of electricity, than for the protection of the building on which the conductor is erected.

What we really wish is to prevent the possibility of an electric discharge taking place within a certain region, say, the inside of a gunpowder manufactory.

If this is clearly laid down as our object, the method of securing it is equally clear.

An electric discharge cannot occur between two bodies unless the difference of their potentials is sufficiently great compared with the distance between them. If, therefore, we can keep the potentials of all bodies within a certain region equal or nearly equal, no discharge will take place between them. We may secure this by connecting all these bodies by means of good conductors, such as copper-wire ropes; but it is not necessary to do so; for it may be shown by experiment that if every part of the surface surrounding a certain region is at the same potential, every point within that region must be at the same potential, provided no charged body is placed within the region.

It would therefore be sufficient to surround our powder-mill with a conducting material (to sheathe its roofs, walls, and ground-floor with thick sheet-copper), and then no electrical effect could occur within it on account of any thunderstorm outside.

There would be no need of any earth-connection. We might even place a layer of asphalt between the copper floor and the ground, so as to insulate the building. If the mill were then struck with lightning, it would remain charged for some time, and a person standing on the ground outside and touching the wall might receive a shock; but no electrical effect would be perceived inside, even on the most delicate electrometer. The potential of every thing inside, with respect to the earth, would be suddenly raised or lowered, as the case might be; but electric potential is not a physical condition, but only a mathematical conception, so that no physical effect could be perceived.

It is therefore not necessary to connect large masses of metal, such as engines, tanks, &c., to the walls, if they are entirely within the building.

If, however, any conductor, such as a telegraph wire or a metallic supply-pipe for water or gas, comes into the building from without, the potential of this conductor may be different from that of the building, unless it is connected with the conducting shell of the building. Hence the water or gas supply-pipes, if any enter the building, must be connected to the system of lightning-conductors; and since to connect a telegraph-wire with the conductor would render the telegraph useless, no telegraph from without should be allowed to enter a powder-mill, though there may be electric-bells and other telegraph apparatus entirely within the building.

I have supposed the powder-mill to be entirely sheathed in thick sheet-copper. This, however, is by no means necessary in order to prevent any sensible electric effect taking place within it, supposing it struck by lightning. It is quite sufficient to enclose the building with a network of good conducting substance. For instance, if a copper wire, say No. 4, B.W.G. (0·238 inch in diameter), were carried round the foundation of a house, up each of the corners and gables, and along the ridges, this would probably be a sufficient protection for an ordinary building against any thunderstorm in this climate. The copper wire may be built into the wall to prevent theft, but it should be connected to any outside metal, such as lead or zinc on the roof, and to metal rain-water pipes.

In the case of a powder-mill, it might be advisable to make the network closer by carrying one or two additional wires over the roof and down the walls to the wire at the foundation. If there are water- or gas-pipes which enter the building from without, these must be connected with the system of conducting-wires; but if there are no such metallic connections with distant points, it is not necessary to take any pains to facilitate the escape of the electricity into the earth.

It is desirable, however, to provide for the safety not only of the building itself, but of the system of conductors which protects it. The only parts of this system which are in any danger are the points where the electricity enters and leaves it. If, therefore, the system terminates above in a tall rod with a sharp point, and downwards in an “earth wire,” the external discharge will be almost certain to occur at the ends of these electrodes, and the only possible damage will be the loss of a few particles from their extremities; but even if the rod and wire were destroyed altogether, the building would still be safe.

ON BOILER AND FACTORY CHIMNEYS AND LIGHTNING CONDUCTORS. BY R. WILSON. 1877.

(_Abstracted by Prof. T. Hayter Lewis, F.S.A._)

The author refers to the wide-spread disbelief in the efficiency of conductors, the common opinion being that metallic bodies, especially when pointed, attract lightning, and are therefore dangerous. This is quite erroneous.

“On an electrified cloud passing over a pointed conductor, the opposite and induced electricity of the earth is discharged from the point of the conductor, and the cloud and air are often thereby neutralized without producing lightning at all. But when a discharge does take place, the conductor offers a line of comparatively small resistance.”

The author further says that, “if electrified clouds be driven to the erection in such masses that the opposite electricity does not stream away from the point of the conductor in sufficient quantities to prevent a spark from passing, the spark or flash will pass from cloud to conductor in preference to any neighbouring point.”

He refers to the safety of conductors, as shown by Sir W. S. Harris’s reports.

When injury to buildings has occurred where lightning rods are fixed, they have been “ignorantly and wrongly applied,” or joints have rusted, the rods been broken, or earth contact has become imperfect.

He refers to Harris and Faraday as to sectional area of conductor. Considers a rope to be better than a rod, as it is less liable to be fractured and to have badly formed joints.

The upper extremity should project into the air as high as the diameter of the chimney top.

The rod should not be inside a chimney, as gases are liable to injure it.

The conductor should communicate with all metal in the chimney.

Insulation is not required.

All contact between copper and iron should be avoided on account of galvanic action.

Earth contact should be tested every year. Anderson’s galvanometer approved of for this.

NOUVEAU PARATONNERRE ACCEPTÉ PAR L’ACADÉMIE DES SCIENCES. PAR JARRIANT. 8vo. Paris. 1877.

(_Abstracted by G. J. Symons, F.R.S._)

This pamphlet is really a letter by M. Francisque Michel respecting some new patterns of lightning conductors made by M. Jarriant, and submitted to the Académie des Sciences by M. le Comte du Moncel. The author states that there have been many theories as to the advantage of conductors rising to great heights above buildings, and that, on the other hand, some persons have urged that buildings should bristle all over with points, and thus prevent any disruptive discharge. He thinks that, owing to the translation of the storm-cloud by the wind, these short points will not always have time to act, and says that the only rational plan is to place a conductor high above the house it is intended to protect, and so constructed that it, and it alone, offers a path of scarcely appreciable resistance to the electric discharge. He says that in Germany they put a metal sphere on the top of the conductors, but in France, both the Academy and the Commission of the City of Paris have advised that they should terminate in a point.

M. Francisque Michel says that formerly a conductor was supposed to protect all objects within a cone whose base had a radius of twice the height of the conductor; but that he and M. Félix Lucas had investigated the question geometrically, and have arrived at the conclusion that the radius cannot exceed 1·75 of the height. Hence, in many buildings, it became necessary either to increase the number of the conductors or to make them more lofty, both alternatives leading to increased expense. M. Jarriant’s design, which consists of galvanized angle iron bolted together, enables the increased elevation to be obtained at a price twenty per cent. below that of the old patterns. The angle irons themselves offer much surface, their angles are useful for discharging electricity, and they carry at the top the copper terminal recommended by the Académie.

A PRACTICAL TREATISE ON LIGHTNING CONDUCTORS. BY HENRY W. SPANG. Philadelphia. 1877.

(_Abstracted by Prof. T. Hayter Lewis, F.S.A._)

“The identity of electricity, manifested by friction, with that contained in the atmosphere, was not fully verified until Franklin’s experiment with his kite in June, 1752.”

“In restoring the equilibrium between the opposite electricities of high potential, the discharge will pass by the shortest path, even though a poor conductor, in preference to a longer path through a good conductor.”

The electricity of the earth is usually negative—of the atmosphere, usually positive.

He quotes experiments at Kew to this effect.

The friction of solid and liquid particles against the earth, and against each other in the air, produced by the wind, is a source of atmospheric electricity.

The height of the lower part of the thunder-clouds above the sea in the United States averages about 2,500 feet.

Dense thunder-clouds are good conductors, and are electrified to a certain extent by the induction of the electricity contained in the surface-earth. As electricity accumulates in the thunder-clouds it acts by induction on the surface-earth, and causes a corresponding increase of potential in the earth and the objects thereon.

He alludes to the vitreous tubes (fulgurites), 5 feet to 75 feet deep, as being formed by electricity passing to the subterranean water-bed through sand or other dry earth.

A highly positively electrified cloud within 3,000 feet of a building causes the latter to be intensely negatively electrified by induction.

So also the earth beneath the building and the upper portion of the subterranean water bed.

Whatever offers the _least_ resistance to the stroke will be its chosen path and it will never leave a very good line of conductors, which is in a short path between two opposite electricities, for an inferior one.

151 persons are killed by lightning annually in the United States, France, England, and Switzerland.

He quotes Sir W. S. Harris’s system for the Navy as preventive.

There is no absolute safety anywhere out of doors. It can only be found inside a structure having good conductors, with good earth connections.

Conductors cannot prevent disruptive discharge. They simply furnish a good path for lightning which passes over them without doing any damage.

_Protective Area._—A committee appointed in 1875 by the Prefect of the Seine reports as protected, a circular space whose radius is equal to 1·45 [Should be 1·75, see page (67). Ed.] of height of conductor. But this is not always to be relied upon.

It is necessary that a conductor extend along the ridge, gable ends, and eaves of a house, and above each chimney.

Lightning is electricity of very high potential, and the difference of conductivity between the resistance of copper and iron to a lightning discharge is small and practically amounts to nothing.

Iron rod conductors not to be less than 7/16 inch diameter. No case is recorded where such a rod, properly connected with the earth, has been fused or greatly heated by lightning.

Paint or an ordinary amount of rust does not affect conductivity.

A conductor of large surface exercises a much greater protective action than the same quantity of metal in the form of a wire or solid rod.

Not because electricity in motion resides on the surface, but that the expansive action of a discharge may have a wider scope _through_ the metal.

So iron rain water-pipes are good conductors, and should be connected with metal spouting, conductor on ridge, &c.

Cable conductors bend easily and can be made in one length, so often answer better than bars.

If earth connection is good, rusty joints are of little consequence.

Conductors are not to be insulated.

Iron pipes for gas, water, heating, &c., also iron columns extending from basement to near the roof are to be connected with conductor and earth terminals.

The pipes on each side of gas meter are to be connected by iron bands.

Air terminals are to rise about 4 feet above each chimney or other elevated projection.

High steeples to have horizontal conductors round them at every 20 feet in height connected with vertical conductors.

One terminal in the centre of a building not over 25 feet long or wide is sufficient, or one at each end of the ridge. One to each 20 feet of a large building, with one at each end and to each chimney, &c.

When the horizontal portion of a lightning conductor, or path along the roof of a building from ridge to eaves (_sic_) exceeds 50 feet in length, the path becomes rather indirect for a lightning discharge, which is then apt to select a shorter route through the building.

The upper part of terminal need not be gilt.

Points are practically of no use.

Chimneys are very likely to be struck, owing to the heated air rising from them.

Provide against this by metal caps.

There is danger also, owing to the vapour rising from them, from barns stored with new hay or grain, stables, schools, churches, &c., containing many people, flocks of sheep, &c.

Earth terminals must be in moist ground.

The author quotes Prof. F. Jenkin as to the difference of conductivity between well moistened and perfectly dry earth (as porcelain, &c.) in electricity of low potential, as 1,000,000,000,000 to 1.

Gas and water mains usually 4 feet or so deep in dry earth, therefore not good conductors.

Examples quoted of injury to their joints by lightning, which passed from conductors to the mains.

Suggests, as earth terminal, an iron pipe, 10 feet long, 2 inches diameter, open at each end, perforated at sides, put in vertically, and having the water from pipes for rain and waste led into it.

To be 8 feet from foundation.

Gives engravings of numerous forms proposed for conductors, most of them being defective, and none show improvement on Franklin’s round rod.

Copper rods held by iron staples, and connected with iron earth terminals, are bad, owing to galvanic action.

Copper wires in cable conductors become brittle, and snap when vibrated by the wind; sometimes, also, they are eaten away by electrolytic action.

He gives a drawing of a house protected as suggested by him, viz., by metal rain water-pipes connected with the metal gutters and ridge; also with his improved earth terminal by a good iron bar conductor.

Gas, water, and other pipes are to be connected together, and with conductor.

These often give better path for lightning than the conductors.

But dangerous if without proper earth terminal.

He disagrees with Prof. C. Maxwell’s theory as to disconnecting the metal covering, &c., of buildings from the earth.

Lightning conductors detached from buildings do not afford absolute protection.

Lightning has great affinity for gas-holders, so one of the nearest guide columns should be connected by a metallic conductor with the pipe leading to street main, and also with a vertical earth terminal.

When a telegraph line is altogether metallic, well insulated upon poles, &c., and not metallically connected with the earth, the electricity of a storm-cloud will not exert so strong an inductive influence upon it as upon a line whose ends terminate in the earth.

Line wire is often melted, poles and apparatus shattered, and employés sometimes killed.

As a remedy, a galvanised iron wire is now fastened to every fourth pole by iron staples, from 4 inches above the top of the pole to a coil about 10 feet long of iron wire beneath its lower end.

UEBER BLITZABLEITER UND BLITZSCHLÄGE IN GEBÄUDE WELCHE MIT BLITZABLEITERN VERSEHEN WAREN. VON G. KARSTEN. Kiel. 8vo. 1877.

(_Abstracted by R. Van der Broek._)

In this pamphlet Dr. Karsten gives an account of two cases in which buildings that were provided with lightning conductors were damaged by lightning. The author states that the statistics for the year 1873 show that in Schleswig-Holstein twenty-six per cent. of all the cases of fire were caused by lightning; 1/130th part of these cases occurred in the towns and the remainder in the country.

Do lightning conductors guarantee absolute protection? The author answers this question as follows: There is no absolute certainty in empirical matters; each new case may direct our attention to circumstances that had been overlooked. If lightning conductors cannot be said to ensure perfect safety, they certainly afford a very high degree of protection.

The flash of lightning which struck the church at Garding, on the 18th of May, 1877, fractured the conductor in fifteen places and pierced the wall of the steeple in two places. The inefficiency of the conductor resulted from the carelessness with which it was fixed; the line was laid down the north side of the steeple and fastened with twenty-five wall eyes; these wall eyes were hammered too deep into the wall, thus damaging the line and forming a short and sharp bend in each case, besides also unduly straining the wire. The damage to the steeple was the consequence of a neglected secondary circuit. There are an excessively large number of tie-rods in the steeple; the heads of these rods are not connected together, neither are they, except in one case, in close proximity to any of the larger masses of metal that are about the building. The conductor passed close to one of those heads; the south side of the steeple, where the opposite head is, becoming wet through the rain, a secondary circuit was formed, and a return shock followed; the damage to the steeple was trifling.

The rod was provided with a conical point rather blunt but surmounted by a short platinum point. The copper line-wire was of good material—not of a uniform thickness, but at the weakest places not weighing less than 240 grammes per lineal metre (8 oz. per yard or rather less than ¼ inch diameter if solid). The earth-plate was sunk into a well 10 metres deep, and tested faultless after the discharge.

ÉTUDE SUR LES PARATONNERRES LEUR CONSTRUCTION LEUR INSTALLATION. PAR JARRIANT. 8vo. Paris. 1878.

(_Abstracted by G. J. Symons, F.R.S._)

This pamphlet opens with two pages devoted to the consideration of Michaëlis’s work published in 1783, “De l’effet des pointes placées sur le Templè de Salomon;” then it becomes more practical, refers to the Academy of Bordeaux propounding in 1750 the question as to the identity of lightning and electricity, and to Franklin’s letter in the same year to Collinson, giving his reasons for believing in the analogy; states that the experiments suggested by him were repeated by Buffon and Dalibar in March, 1752, and subsequently repeated at Marly before Louis XV. Then the writer refers to the erection of the first conductor in France, to the popular displeasure which it excited, and to the long legal process before the proprietor was allowed to keep it in position.

The author thinks that in many cases it is better to slightly increase the number of conductors than to make them of excessive length, because the latter course causes them to fatigue and jar the roof timbers by their vibration with the wind.

Respecting platinum points he speaks strongly and to the following effect:—“I have already mentioned that Franklin’s first conductor was melted. Since then, the upper terminals of conductors have been made of platinum, because it is the least fusible, the least oxidizable of all metals, and a very suitable one for making into points. Moreover, the sharper a point the greater its preventive action, and hence I condemn every conductor without a platinum point. Although some manufacturers employ simple copper cones, which may certainly last some time without deterioration, believing in the desirability of the points being always in perfect order, I reject their system entirely.”

Few persons are used to making platinum points, it is a Parisian speciality, those which the author prefers, form a cone of about 10 degrees at the opening of the point and are about 1½ inches long, then screwed and soldered into a mass of copper forming a nut on the conical copper rod, which is 1 foot or 1 foot 6 inches long. The platinum point thus mounted can only give rise to a galvanic action so extremely feeble as not in the least to affect the durability of the apparatus. Some persons for the sake of cheapness suppress this platinum point, but they are wrong, the saving is slight and the result defective. The author objects to conductors made of bar iron because the joints are always defective, and if the section be too small they may be so heated as to set fire to the charcoal in which the lower extremity is buried.(!) However, the author prefers a rope, but he does not say whether of iron or copper, and he puts a strand of hemp in the middle so as to make it more pliable.

“Arrived at the ground the conductor ought not to be in immediate contact with the earth, for the damp would slowly destroy it; we avoid this (?) by making it pass through a trough filled with coke. Experience has shown that iron thus buried in coke undergoes no change even during thirty years.... Broken coke is better than charcoal because of the great quantity of water which it absorbs.”

The author then says that after passing through this trough the conductor must be continued into a well, or into very moist earth, and should end with a discharger like a fork with many prongs.

He recommends that all the iron be galvanized.

Although the concluding paragraph, coming from a manufacturer, sounds rather like self-recommendation, it undoubtedly contains important truths. M. Jarriant says:—

“I cannot too strongly advise that in erecting conductors those specialists should be employed, whose studies and constant practice enable them to ensure perfect work. It is necessary also that every workman should remember that in placing a lightning conductor he holds in his hands the lives of men, that he should feel conscientiously interested in the perfection of his work, and, finally, that he should feel that it is a mission which he fulfils, and not a mere matter of trade at which he works.”

REPORT ON THE LIGHTNING CONDUCTORS OF THE SMALL ARMS AMMUNITION FACTORY AT DUM DUM, CALCUTTA. BY W. P. JOHNSTON. Government Telegraph Press. 1878. 4to.

(_Abstracted by W. H. Preece, C.E._)

This is an interesting report of a careful inspection and an electrical testing, by a skilled electrician, of the lightning conductors at this place. Although most carefully protected by well arranged and adequate copper rods, copper bands, iron rods, and iron tubes, and terminated in points, it was found that the points were covered either with rust or with paint, and that the earth connections were so bad as to render the buildings unsafe, although there was no difficulty in obtaining a good earth at any part of the factory.

ATMOSPHERIC ELECTRICITY. BY DAVID BROOKS. Philadelphia. 1878. 8vo.

(_Abstracted by W. H. Preece, C.E._)

A pamphlet by a distinguished American telegraph engineer, giving his view on the magnitude and origin of atmospheric electricity, which he attributes principally to the friction of air on ice in the Polar regions, and which circulates southwards in the higher regions of the air, and northwards in the crust of the earth. Hence also Aurora Borealis which is always preceded by high winds and most frequent when the earth is covered with snow.

Thunderclouds are usually about 2 miles high and from 13 to 23 miles thick. Lightning is much less frequent in mountainous than in plain countries. Copper lightning conductors are often applied to iron ships and iron buildings, but absurdly, as they are in such cases superfluous.

The author advocates immense earth plates where there are no gas- and water-pipes, which he calls the best lightning rods ever erected, because they are electrically in perfect connection with the earth. The track of a railway makes a capital earth. He has never known an accident where proper conductors were used, whereas he has known many accidents from imperfectly and improperly constructed lightning rods, though of the latest and most approved patents.

CATALOGUE MESSRS. A. COLLIN ET FILS, Article PARATONNERRES. Paris. 4to.

(_Abstracted by Prof. T. Hayter Lewis, F.S.A._)

The authors state that a Municipal Commission has recommended, to the exclusion of all other points, copper about ¾ inch diameter, terminating in a cone of 30°.

As to the area protected Messrs. Collin refer to the reports of the Academy in 1823 and 1854, admitting, as a limit of protected area, a circumference of which the radius equals double the height of the upper terminal for slightly elevated buildings, and simply the height for towers, &c., but this rule is badly defined.

The authors quote formulæ based upon the assumed altitude of the storm cloud, but state them to be unreliable.

The Academy in 1854 reports that an electrified cloud is equally attracted at equal distances by a metallic part of the roof and by the terminal of the conductor.

Exposed points of pinnacles, &c., are to be united to main conductors.

If copper be too expensive use iron wire.

The conductors are to be supported at about 10 centimetres (4 ins.) from walls and roofs.

The Academy recommends them to be isolated on glass or porcelain, but the New Commission rejects this, and suggests that all metallic parts be united to the conductor,—also recommends that wells be sunk to water level, as earth connections.

But this would often entail a depth of 20 to 100 metres, or even more. So the conductors may be sunk into moist earth and surrounded with coke, and if necessary, may terminate in a sheet of copper.

A good earth is very important. Connection with water mains advised.

The authors have fixed 8,000 lightning conductors on their principle without failure.

They give engravings of the various parts.

They engrave a diagram of a powder magazine which they propose to protect by a tall isolated lightning conductor fixed at a distance from it, and at such a height as that it will be included in a cone whose radius is equal to the height of the conductor.

THE SCIENTIFIC AMERICAN, NOVEMBER 1st, 1879.

(_Abstracted by Alfred J. Frost._)

We learn that a lightning rod company in Cincinatti has patented a system of lightning protection, which consists of an iron rod running along the ridge of the building with points at each end projecting upwards. It is supported upon large glass insulators, and has no electrical connection with the building, and no rod running to the ground. It is said that there are many public buildings in Iowa which have been provided with this system of lightning rods.

Professor Macomber, of the Iowa Agricultural College, in reply to an inquiry, says that it would be possible that a house insulated with a glass foundation could be struck by lightning, but adds, “By insulating a building the tendency to be struck by lightning would be very much lessened, and the severity of the shock much decreased. Practical illustrations of this can easily be obtained by means of an electrical machine. A spark can be made to pass from the machine to an insulated body, although the force of the shock will be much less than when not insulated. Practically, it would be almost impossible to insulate a building, because after rain commenced to fall it would wet it so that communication with the earth would be established.”

REMARKS ON THE ATMOSPHERIC ELECTRICITY AND ON THE ACTION OF LIGHTNING CONDUCTORS. BY PROF. DR. G. KARSTEN. 2nd edition. Kiel, 1879.

(_Abstracted by H. Van der Broek._)

The author of this pamphlet, Prof. Dr. G. Karsten, states that thunderstorms are particularly dangerous in Schleswig-Holstein. He attributes that fact to the scarcity of woods in that province, not more than five per cent. of the surface being wooded; whilst in the Prussian empire the proportion of woods is twenty-three per cent.

Woods promote a uniform dampness of the atmosphere and lessen the up-current of air, which up-current contributes considerably to the formation of thunderstorms; and the woods thus cause the discharges of the electricity to take place principally between the clouds.

We do not yet know with certainty what the causes of atmospheric electricity are, but we do know under what conditions or circumstances thunderstorms may occur.

Thunderstorms are only formed when a violent condensation of the rarified particles of water, which the atmosphere contains, takes place. Such a sudden condensation, and the consequent formation of a thunderstorm, may occur when two different masses of air—the one moist and warm, the other dry and cold—intermix rapidly. The former of these currents we call the South, or Equatorial current, the latter the North, or Polar current. If these currents penetrate each other, or intermix slowly, long continued falls of snow and rain ensue; if they mix rapidly thunderstorms are formed during the warmer seasons, and sometimes also during the colder seasons.

The Schleswig-Holstein Provincial Fire Insurance Association alone paid, in sixteen years, the sum of £102,832 (an average of £6,427) for damages caused by lightning. This province loses altogether £12,500 per annum through fires caused by lightning.

The author’s very interesting remarks on the construction of lightning conductors are briefly summarised in the following general rules:

1. Copper and iron form the best materials for lightning conductors; lead and zinc may be used for secondary conductors. (Nebenleitungen.)

2. If the conductor be constructed of iron, it should weigh from 1,200 to 3,400 grammes per metre (2½ lbs. to 7 lbs. per yard), according to its length; a copper conductor should weigh, under the same circumstances, from 250 to 600 grammes per metre (½ lb. to 1¼ lbs. per yard).

3. The conductor must be connected with all the projecting corners and pointed parts of the building.

4. There must be no sharp curves or bends in the conductor.

5. The conductor must be connected with all the large and extensive masses of metal that may be about the building. This connection may be made by wires leading towards the rod, as well as in the direction of the earth contact.

6. The rods must be surmounted by good points, which must not be liable to be fused by the discharges of the electricity.

7. The height of the rods must be in proportion to the size and shape of the buildings; but it is better to erect several short rods than one extraordinarily long one.

8. In making the connection with the earth all sharp curves must be avoided.

9. The underground part of the conductor must be made of galvanized metal, so as to minimise the effects of oxidation, or, in case a layer of coke is used, to prevent the action of the sulphur.

10. The earth-contact should terminate in a plate, which, if possible, should always be immersed in water. If this can be so arranged the plate must have a surface ⅒th of a square metre (1 foot square) for conductors for small buildings, whilst a plate of a surface of 2 square metres (5 feet square) will be sufficient for conductors for the largest buildings.

11. Where a permanent contact with water cannot be established, several plates of a larger size must be used, and laid in a stratum of coke.

12. In the case of very large buildings, provided with several rods and secondary conductors, several earth-contacts should be made which should be connected with each other.

With reference to the upper terminal point, the author remarks, in an appendix to the second edition of his pamphlet, that it should be made of a conical form of a basis of from 20 to 30 millimetres (0·8 in. to 1·2 in.), and of a length of 150 millimetres (6 inches); it must consist of pure copper and be gilded. It is useful to provide it with a platinum needle 15 millimetres (half an inch) long, and about 4 millimetres (0·2 inch) thick at its base; or with a cone of chemically pure silver, the proportion between whose base and height must be as 2 : 3.

LIGHTNING CONDUCTORS. BY RICHARD ANDERSON, London, 1879.

(_Abstracted by Prof. T. Hayter Lewis, F.S.A._)

_Historical Facts_—

The following are brief references to some of the principal facts recorded in this volume:—

1600 A.D. Dr. Gilbert showed that magnetic and electrical phenomena were emanations of one force.

1650. Otto Von Guericke constructed a little electrical machine (mainly of a ball of sulphur on a revolving axis).

Sir I. Newton constructed a machine of glass, but used it merely for amusement.

1675. The polarity of a ship’s compass was found to be reversed by a stroke of lightning.

1708. Dr. Wall said that the light and crackling of rubbed amber seemed in some degree to resemble lightning and thunder.

1709. F. Hauksbee, F.R.S., showed the similarity between the electric flash and lightning.

1720. S. Gray, F.R.S., showed this by experiment, but was discredited.

1745. The first great step in this science was made at Leyden, by J. N. Allamand and P. van Musschenbroek, who discovered the properties of the Leyden jar. The priority of this invention disputed by Dr. Winckler, of Leipzig; a mania for experiments arose. Louis XV. tried them, unsuccessfully, on 180 of his Guards; but with perfect success on 700 Carthusian Monks.

1746. _Dr. Franklin_, of Philadelphia, saw some electrical experiments, and in

1747 received a glass tube and some books on electricity from London; then began to make experiments; sold his business, bought apparatus and made electricity his study. Discovered that electricity passed most easily and quickly through sharply pointed metals; that it was positive and negative; and that lightning and electricity were identical. He sent these results to the Royal Society, who refused to allow them to appear in their Transactions; he then published them in a pamphlet. It was not appreciated in England, but met with great applause in France, and was also translated into German, Italian and Latin.

1747. The subject was taken up in England in a thoroughly practical manner. Dr. Watson, Mr. Folkes, Lord C. Cavendish, Dr. Bevis, &c., experimented on a wire stretched across the Thames. The charge was found to come back by the water. The same result followed through moist earth. A gun was fired at a distance of four miles; the passage of the charge appearing to be instantaneous.

New experiments were made by Dr. Watson with glass rods, 2 and 3 feet long and 1 inch diameter. These showed that the rods, &c., contained electricity only as a sponge holds water.

1752. Experiments by Messrs. Dalibard and De Lor, at Marly-la-Ville, near Paris, in May, described.

1752. July. Franklin tried his Kite successfully, then his fame was established, and he erected, on his own house, the first lightning rod.

1753. Prof. Richmann, St. Petersburg, was killed whilst experimenting. The use of conductors opposed, violently in France, by Abbé Nollet.

1755. An earthquake at Massachusets, was laid to the charge of the numerous lightning conductors. Franklin pushed their use by means of his publication, “Poor Richard,” which had an enormous circulation; particulars given showing success of lightning conductors.

1762. The first lightning conductor used in England, and Dr. Watson asked to send in designs for lightning rods for ships. He did so, but in an unpractical way, and they were disused.

1764. St. Bride’s steeple struck.

1769. The Dean and Chapter asked Royal Society for advice as to protecting St. Paul’s. Committee of Royal Society disagreed as to whether rods should be pointed. Pointed rods were used.

1769. The first conductor fixed to a public building in Europe was to a church steeple in Hamburg.

De Saussure, at Geneva, had some difficulty in explaining to the citizens that his conductors were not dangerous to his neighbours. There was a great fear, generally, as to their use, _e.g._, a lightning rod was erected, secretly, by the Priests at the Cathedral of Siena, and excited great terror in the townsmen when discovered, but a terrific stroke of lightning left the tower uninjured.

1772. Dr. Ingenhousz’s experiments.

1774. The University of Padua protected by conductors.

1777. A building at Purfleet was struck though it had a conductor, but this was shown to be defective.

Sir J. Pringle had to resign his Presidency of the Royal Society because he advocated points, but experiments were made and ended in favour of points.

1778. The Venetians decreed that lightning rods should be erected throughout the Republic.

1819. Electro-magnetism discovered by Œrsted.

1822. Sir W. S. Harris took up the question of providing good conductors for ships, and afterwards made a list of 250 accidents to ships in 40 years; also of 200 seamen killed or wounded in that time. At this time no importance was attached to the subject in England, except in the case of Sir W. S. Harris. He insisted on the necessity of lightning rods. A commission of inquiry was appointed by H.M. Government to investigate the best method of applying lightning rods to H.M.’s ships, and they reported (in 80 pages folio) that lightning rods were rather new fangled things, but might be tried, without special harm to anybody. So most ships were fitted with them after Sir W. S. Harris’s design. He was knighted in 1847. An iron built ship, metal rigged, is as well protected from lightning as Solomon’s Temple. Harris combated the opinion of those who said that lightning rods attracted lightning.

Even in 1826 a government engineer recommended, on this ground, that all lightning rods should be pulled down, and, in 1838, the Governor-General of India ordered this by the advice of his “scientific officers.” This was not countermanded until several buildings had been destroyed.

Army circulars are now regularly issued, containing Sir W. S. Harris’s suggestions. (These quoted by Mr. Anderson).

Sir C. Barry suggested that Sir W. S. Harris should design lightning conductors for new Houses of Parliament. He reported in 1855. He used conductors of 2 inch copper tubes, ⅛th-inch thick, to towers and other elevated parts, secured to masonry by metal staples. The cost was £2,314.

As to conductors, Le Roy recommended that they should rise not less than 15 feet above chimney and summit of any edifice.

Mr. Anderson gives technical names of parts of lightning rods in different countries. Chains first used, and gave rise to many accidents. Tin and lead conductors tried; lead especially, from its easy application to sharp curves, &c., but it is liable to be broken, and is a bad conductor; so it went out of use.

Some particular buildings are constantly under attack from lightning, _e.g._, Church of Rosenberg in Carinthia, not standing in a very high position, but greviously damaged in 1730, &c.; rebuilt in 1778, with lightning rod, and not injured since. Some of these effects may be explained on meteorological grounds: the height and thickness of the charged clouds only slightly varying, perhaps, in districts where there are prevailing winds. The height of clouds sometimes enormous. Instances are given of their being 15,000 to 25,000 feet above the sea. But sometimes clouds are almost flat on the earth, two instances are given of this. A remarkable and often fatal discharge is the “return stroke,” always less violent than the direct stroke, but often very powerful, and caused by the inductive action exerted by a thunder-cloud. Men and animals are charged with opposite electricity to the cloud. When the latter is discharged by the recombination of its electricity with that of the ground, the induction ceases, and all bodies charged by induction return to a neutral condition. Hence the dangerous “return stroke.” Lord Mahon first demonstrated this by experiment. _As to origin_ of atmospheric electricity, De Saussure considered it due to the evaporation of water by the sun’s heat. Peltier (1765–1845) considered the earth itself to be one immense reservoir of electricity. As light comes from the sun, so electricity is generated by heat from the interior of the globe. No electricity is produced by atmosphere, nor held by it, except temporarily.

There is no recorded case in which a well made lightning rod, with “good earth,” did not do its duty.

In 1822 there was an extraordinary number of thunder storms in France, so lightning rods were ordered by Minister of Interior for all public buildings, and he applied to the Academy of Sciences for advice. 1823. A Committee (Gray Lussac, &c.) reported. They laid it down, as a rule, that a lightning rod protected a circular area, having a radius of double the height of the rod; and they said nothing about regular inspection of lightning rods. So disasters occurred, and another Committee was appointed (Pouillet, &c.). They reported 1854. The theory as to the protected area was abandoned. It was recommended that lightning rods should have as few joints as possible. The joints to be well soldered, the points to be of copper (not platinum), and not to be very finely pointed. The rods to be of copper, not iron. The Louvre was well protected by lightning rods, but slightly injured, 1854. Another Committee was appointed, and, 1855, Pouillet again reported on its behalf. It recommended that the points (always of copper) should be thicker, and the rod to have a never-failing connection with water or moist earth, 1866. Several French powder magazines were struck though provided with lightning rods, and the Minister of War asked the Academy for another report. Another Committee (Becquerel, &c.) was appointed, and, 1867, Pouillet again reported. He defines lightning as an immense electric spark passing from one cloud to another, or from cloud to earth, to restore equilibrium. The best protection for a building would be iron rods surrounding it on all sides, and passing deep into ground. Conductors should be inspected every year.

The conductor now remains essentially as Franklin invented it. Of the inner nature of “lightning” we are utterly ignorant. The first conductors were always of iron as being cheap.

Sir H. Davy pointed out the different conducting powers of different metals. Becquerel, Lenz, Ohm, and Pouillet made similar investigations, with the following results:—

───────────┬─────────┬─────────┬─────────┬─────────┬─────────┬───────── │ Silver. │ Copper. │ Lead. │ Tin. │ Iron. │Iron = 1 │ │ │ │ │ │Copper = ───────────┼─────────┼─────────┼─────────┼─────────┼─────────┼───────── │ │ │ │ │ │ Davy │ 109·1 │ 100 │ 69·1 │ │ 14·6 │ 6·85 │ │ │ │ │ │ Becquerel │ 73·5 │ 100 │ 8·3 │ 15·5 │ 15·8 │ 6·33 │ │ │ │ │ │ Lenz │ 136·25 │ 100 │ 14·62 │ 30·84 │ 17·74 │ 5·64 │ │ │ │ │ │ Ohm │ 35·60 │ 100 │ 9·7 │ 16·8 │ 17·4 │ 5·75 │ │ │ │ │ │ Pouillet │ 81·26 │ 100 │ │ │ 18·2 to │ 5·49 to │ │ │ │ │ 15·6 │ 6·41 ───────────┴─────────┴─────────┴─────────┴─────────┴─────────┴─────────

(The difference being owing, probably, to the greater or less purity of the Metals.)

1815. Brass wire rope generally used in Bavaria, but a steeple was struck down though with a brass wire conductor 1 inch diameter. The real defect was “bad earth,” but attributed to bad form of conductor; so this was abandoned. Brass not a reliable metal, and often destroyed by smoke. Purity of copper essential.

Professor Matthiessens’ experiments shewed that the conductivity of copper varied from—

Pure 100· to Australian 88·86 Russian 59·34 and Spanish, Rio Tinto 14·24

Hotel de Ville, Brussels, lightning rods designed by Professor Melsens on the principle of a great number of small ones in preference to one of large size, and covering building with network of metal, having many points and many earth contacts. He considers that the relation of section to surface of the lightning rod has a marked and definite, though unknown, result.

Author describes weathercocks and methods of fixing them.

_Lightning rods generally_—methods used in France: Terminal rods, usually of wrought iron, galvanized; their height depends on the size and area of building it protects. This is generally to be considered to be within a cone of revolution, of which the radius = height of rod above ridge × 1·75.

Points described. The conductors are of iron, rebated, soldered, and bolted at joints, with lead between. Bent plates of copper introduced to provide against contraction and expansion. In large buildings, metallic connections are formed on ridge by iron bars-¾ in. × ¾ in.

Precautions are taken against the destruction of iron underground, viz., by enclosing it in vertical sprints of wood, tarred or creosoted, rising a few inches above ground, or by a coating of tar or by a wrapper of sheet lead. The earth connection is a trough filled with broken charcoal, through which the conductor passes, ending in several branches, or in a grating between layers of charcoal. Galvanized iron cables sometimes used, and (rarely) copper of ½ in. diameter.

_America._ Gutters and water pipes, &c., used where possible. If the roof be of wood, slate, &c., a conductor is laid along ridge, and connected with gutters and rain water pipes. If these latter be less than 3 in. diameter, the conductor is often extended from roof down the side of building close to the pipe. All metal chimney caps, railings, water and gas pipes, and other large or long pieces of metal, inside and out, are connected with conductor. The upper terminal usually projects 4 ft. above chimney or other highest part of building. It is a round rod, 7/16th in. diameter, hammered out to join it to conductor. A building 25 ft. wide and broad has one terminal in centre and one at each end. In larger buildings, one terminal to each 20 ft. of roof. Not always pointed.

Steeples have horizontal conductors at every 20 feet, connected with vertical conductors, to provide against discharge in centre, caused by deflection of discharge in the air by rain. Conductors are fixed to buildings by iron staples or straps; the earth connections are similar to ours. Also are used iron pipes, about 3 in. diameter and 10 ft. long, placed vertically in moist earth and carefully connected with conductor.

_Newall’s system_: Copper conductors are the best, and in the end, cheapest. Terminal rods are usually 3 to 5 ft. long, and ⅝th to ¾ in. diameter, branching out at top.

_German_ “reception rod” described as being of iron, 10 to 30 ft. long; the area of protection theory discredited. The electric fire, seeking its nearest path to earth, is not to be diverged from it to the rod. These high rods of no use except, _e.g._, near high trees, and are often dangerous from being blown down. Barns containing new hay are likely to be struck, as hay sends out stream of warm air.

Designs explained for protecting private houses by short terminal points to chimneys, gables, &c. A copper rope at least ⅝th in. diameter should be used; a copper rod, ½ in. diameter, has never been fused, so far as is known. In chimneys of manufactories, where rope is liable to corrosion, a greater thickness should be used.

Laughton-en-le-Morthen steeple injured, though with lightning rod, but this was only a small, thin copper tube, ⅞th in. external diameter, and 1/32 in. thick; weighing 8oz. per foot, or equal to a rod about 0·12 in. diameter, the joints were corroded, and the earth contact was imperfect. Nevertheless, only one buttress was injured. It is of little consequence whether the conductor be inside or outside, if it be carried to earth by the shortest route. At first it was more generally put inside in France, but this was given up for fear of accidents. But it is beyond controversy that a good conductor is absolutely harmless to all surrounding objects, and a man might lean against a copper half-inch rod, carrying off a heavy stroke of lightning into “good earth,” without being aware of its passing.

It is useless and dangerous to isolate conductors from buildings. All masses of metal should be connected with conductors.

Prof. Clerk Maxwell’s theory described (as to disconnecting the conductors, &c., from the earth): He states that it is not necessary to connect masses of metal, as engine tanks, &c., if entirely within the building, unless a conductor as, _e.g._, telegraph wire, water or gas pipe come into the building from outside, then they must be connected with conductor.

List of accidents from lightning, also deaths or injuries in England and Wales, Prussia, United States, Sweden and Austria.

Particulars of damage to St. George’s Church, Leicester, 1846, and to West-end Church, Southampton. Also, to Merton College, Oxford, and St. Bride’s Church, Fleet Street, none of these having lightning rods.

Wrexham Church struck, this had a copper conductor, but it was too small and the earth contact was doubtful.

List of buildings struck at home and abroad from 1589 to September, 1879, the authorities for the statements being given.

List of powder magazines struck between 1732 and 1878.

_Earth Connections._ Franklin’s report, 1772, strongly urges the importance of this, in speaking of the powder magazine at Purfleet. In ordinary cases, moist earth is sufficient, but in such a case as this he recommends that a well should be dug at each end of magazine, with 3 to 4 ft. of water in it.

The importance of “good earth” is shewn by numerous accidents to buildings, as, _e.g._, in 1779, the church of St. Mary, Genoa, and, in 1872, the cathedral of Alatri, in which latter case, the discharge left moist earth to pass off by a water pipe, which it broke; but the church was uninjured. Also at Clevedon Church, where the conductor passed into a drain which was dry, but the stroke merely injured one buttress and passed off by gas and water pipes.

Mr. Anderson states that earth contacts must be large. That it is important that metal work be connected with lightning rod in at least two parts, to realize a closed metallic circuit, and so offer entry and exit. The earth contacts of the eight conductors of the Hotel de Ville, Brussels, described, viz., their being enclosed in an iron box, 8 in. × 3 in. × 3½ in., with three series of conductors (details given): one passing into a well, another to the gas main, the third to water main.

In ordinary buildings, the grating, with charcoal, coke, or cinders, &c., as before described, may be sufficient; but with large buildings, contact with water is absolutely necessary.

_Periodical inspection._ Author strongly urges this because conductors deteriorate from action of wind and weather above ground; the “earth” often becomes bad, owing to new drains, &c.; buildings may be altered in regard of the quantity and position of metals. An instance is given of damage to a building owing to the change of position of iron safe. Conductors are often displaced by workmen; and the number and position of new gas and water mains, new trees, &c., also influence the power of conductors.

_Appendix._ This contains a very full list of books relating to lightning conductors.

REPORT UPON LIGHTNING DISCHARGES IN THE PROVINCE OF SCHLESWIG-HOLSTEIN. BY DR. LEONHARD WEBER. 1880. 8vo.

(_Abstracted by Alexander Siemens_).

The serious damage caused in Schleswig-Holstein by lightning led to an official inquiry into the subject, the following is an abstract of the first report of the commission.

It is stated that trees, by their gradual but uninterrupted discharge of electricity, have a dispersing effect upon thunder-clouds, and tend to lessen the energy of lightning. In six cases out of the twelve examined, houses with trees close by, were struck, but not so heavily as in another case where the building had no protection whatever. Trees do not, however, afford complete protection to neighbouring buildings, their conductive capacities not being sufficient to convey, in the immeasurably short time required, such heavy discharges of electricity as lightning flashes. This is instanced by their being often wholly, or partially, destroyed by the current, or, as occurred in four cases, by their passing it over to better conductors, buildings, &c.

If a thunder-cloud passed over a perfectly plane surface, the discharge would take place in a vertical line between earth and cloud, but prominent objects, such as isolated trees, buildings, lightning conductors, and iron pumps, reaching down to underground water, act as attractive points, and divert the discharge, the path of which is also influenced by any conductors which happen to come between them and the thunder-cloud, such influence depending upon the capacity of the conductors. So that, generally an electric discharge chooses that path which, taking the distance into account, offers the best means of conduction.

It is frequently found that inflammable material is struck by lightning without being ignited, on account, it is presumed, of the short duration of discharge not allowing the material to become sufficiently hot to burn, but whether the duration of discharge is dependent upon the nature of the charge of the thunder-cloud, or solely upon the condition of the objects struck, has not been ascertained. The latter is, however, not without influence, as in two of the four cases which resulted in fire, the cause was presumably due to newly gathered hay stored at the top of the houses struck, and in the other two cases to trees, which were struck at the same time, the hay and the trees being bad conductors, and prolonging the duration of discharge.

Four cases are given of buildings having lightning conductors being struck.

The first case is that of a windmill, the conductor of which terminated in a sheet of metal placed in a well near the building. The discharge was exceedingly heavy, but beyond the platinum point being almost entirely fused, no other damage was done.

The second is that of a house with two separate lightning conductors, each ending in a copper plate, spirally coiled up, and laid in underground water. One of the conductors was struck, and the lightning passed from it, and, running horizontally along the thatched roof of the house, descended by the other, causing no damage.

The third case refers to a church and, adjoining it, a school building. A portion of the discharge was diverted from the conductor by an anchor in the church wall three metres off (which it magnetized), and forced its way through the ceiling of the school-house to a number of gas brackets, which were turned up towards the ceiling. It was ascertained that the ground floor of the house was completely under water, and well connected to earth through the gas mains and an iron pump, a good continuous conductor thus being formed.

Accordingly, the report recommends that lightning conductors should be connected to the large masses of metal, such as gas and water mains, which are found in our houses.

In the fourth instance a church had a lightning conductor, which was connected to the top of two large iron supports running through the steeple to the nave, and which terminated in a coiled earth-plate, 1 sq. metre (11 sq. ft.), supposed to lie in water 7 metres (23 ft.) underground. The lightning struck the conductor and, passing to the iron supports, sprang from one through the outer wall, close to an iron window frame, and from the other across the stucco ceiling, going to earth 100 feet off through the altar gilding, which it blackened. It was subsequently found that the copper earth-plate was only ⅓ metre (1 ft. 1 in. sq.), and that it was buried loosely round the rod in dry sand, the rod itself reaching 2 to 3 metres further down, and just touching water without an earth-plate, and also that the two supports had no earth connection, thus forming a great danger instead of a safeguard to the church.

DIE KONSTRUKTION UND ANLEGUNG DER BLITZABLEITER ZUM SCHUTZE ALLER ARTEN VON GEBÄUDEN SEESCHIFFEN UND TELEGRAFEN STATIONEN. VON DR. OTTO BUCHNER. Weimar. 1867. 8vo.

(_Abstracted by R. Van der Broek._)

The book is divided into two parts:

1. General, or Introductory, and

2. Practical.

The first, or Introductory part, is sub-divided into:

1. Historical and statistical notes;

2. The theory of atmospheric electricity, and of the lightning conductor; and

3. A chapter on natural lightning conductors.

The great philosopher, Lichtenberg, of Gottingen, said in the year 1794: “People are struck and their dwellings are destroyed by lightning because they will have it so. It does not matter to us whether parsimony, carelessness, ignorance, or anything else is the cause of this.” The author asserts that this dictum may be equally applied to the present generation.

Professor J. H. Winkler, of Leipzig, discovered, in the year 1746, that electricity is the principal cause of thunderstorms.

The first lightning conductor in Germany was erected 1769, at Hamburg, on the steeple of the Jacobi Church.

Between the years 1835 and 1863, a period of 19 years, 2238 persons were _killed_ by lightning in France. The maximum in one year (1835) was 111 and the minimum 48. The total number of persons _struck_ by lightning amounted to 6714; of this large number 1700 persons would have escaped, if they had been careful to avoid the neighbourhood of trees, whilst the storms were raging. The greatest number of the accidents caused by lightning occur during the months of July and August; not a single fatal case is on record for the months of November, December, January, and February. The annual average number of persons killed by lightning was 3 in Belgium, 22 in England, and 10 in Sweden. In the low-lying Departments of France the average is 2 or 3; the average increases rapidly for the Mountainous Departments to 24, 28, 38, 44, and (in Auvergne) 48. The per centage of males in France is 67, females 10, and in the remaining cases the sex was not stated. In Prussia the proportion is 184 males to 105 females, in Sweden 5 males to 3 females.

The largest number of persons killed by _one_ discharge is 8 or 9.

The author states that the return shock is only mechanical in its effects.

Professor Müller lays down the following conditions for lightning conductors:—

1. The rod must end in a very sharp point.

2. There must be no want of continuity between the extreme point and the earth contact: and

3. The different parts of the conductor must be of the requisite dimensions.

In practice we find that the first mentioned condition is incorrect, as sharp points are too liable to be fused.

The rod must be made of a pyramidal or a conical form. Short rods of not above 2 metres (6 feet 7 inches) in length may be made of a cylindrical form. The best form of rod is one tapering from a base of from 50 to 60 millimetres (2 inches to 2·4 inches) in diameter to a diameter of not less than 14 millimetres (0·56 inches). As it is difficult to fix rods of a height of 10 metres (33 feet), it is better to erect one long rod, and several shorter ones on different parts of the roof and connect them together. The principal rod should have a height of from 2½ to 3 metres (8 to 10 feet) and the secondary rods (_Nebenstangen_) should be at least 1 metre (3 feet 3 inches) high.

The form of point universally used in Germany is a strongly firegilded copper cone.

Kuhn advocates the use of chemically pure silver for the points. His arguments in favour of this metal are incontrovertible. The conducting power of silver is 1·36; that of pure copper being 1. The fusibility of silver (1,000 c.) is sufficiently high for the purpose. The atmosphere, unless it contains sulphur in a gaseous or a liquid form, has no effect on silver. Silver is cheaper than platinum, and not more expensive than a gilded copper cone, and it can be easily soldered to other metals.

The point should be screwed on, as well as soldered to the rod. All other but the conical form of point should be rejected.

The best material for the earth contact is galvanised iron.

As regards the protection of sea-going vessels, Snow Harris’s arrangement, converting, as it were, the vessel into one mass of metal, is perfect.

The first practicable lightning conductor for the protection of telegraph wires was constructed by Steinheil in 1846. His arrangement was somewhat modified by Breguet and Fardely. Meiszner introduced a real improvement.

On the Prussian railway telegraphs two “point-systems” are in use, one for small stations, and the other for larger stations.

It is desirable that all lightning conductors be examined once a year. The metallic connection throughout must be perfect, the point must be kept free from rust, and the earth contact must be good. The whole circuit should also be tested by means of a battery and a galvanometer.

EARTH CONNECTIONS OF LIGHTNING CONDUCTORS. BY LIEUT.-COL. STOTHERD, R.E.

(Journal of the Society of Telegraph Engineers, May 12, 1875.)

(_Abstracted by W. H. Preece, C.E._)

Arguing from the case of a powder magazine at East London, Cape of Good Hope, when the iron conductor was led into a cemented water-tank, frequently dry, and where it was destroyed, the author raises two questions:

1. Should such tanks be used for earth?

2. Is iron the proper metal to use?

He gives a decided negative reply to the first, and advocates the use of galvanized iron properly protected from atmospheric action. He suggests rods 1 inch in diameter, or bands 2in. × ⅜in. thick.

In the discussion which followed it was mentioned that the ground about Torquay is so insulated that plates had to be carried out to sea to secure a good earth for the telegraph there, and that of the numerous churches which had been inspected, there was not a single conductor that could be passed. It was pointed out that when copper conductors were fixed with iron wall-eyes—a frequent thing—galvanic currents were set up, and the conductor destroyed at the ground line.

It was stated that the earth connection of a supposed perfect conductor was found to be equal to a resistance of 1,000 Ohms.

Mr. Preece, Major Malcolm, R.E., Dr. Mann, Mr. Pidgeon, Mr. Kempe, Mr. Graves, Mr. Spagnoletti, and Mr. Latimer Clark, took part in the discussion.

REMARKS ON SOME PRACTICAL POINTS CONNECTED WITH THE CONSTRUCTION OF LIGHTNING CONDUCTORS. By R. J. MANN, M.D., F.R.A.S. (_Quarterly Journal Meteor. Soc._, October, 1875).

(_Abstracted by G. J. Symons, F.R.S._)

States that there are certain principles accepted as established facts, _e.g._, that conductors should be of metal of high conductivity, and of adequate dimensions. That in 1854 the French electricians held that a “quadrangular iron bar ¾ in. diameter, was sufficient in conducting power for all purposes.” Since then, wire ropes, owing to their pliability, have nearly superseded solid rods, and copper has been preferred to iron because of its higher conducting power and less liability to oxidise. But provided that the iron be galvanized, and of five times the sectional area of a copper conductor, considers the metal immaterial.

Author states that the resistance of a conductor increases with its length, therefore sectional area of conductor must be increased for lofty buildings. Modern French electricians employ copper rope 0·4 to 0·8 in. diameter. M. R. Francisque Michel considers galvanized iron wire rope 0·8 in. diameter sufficient for all ordinary cases. Copper wire rope 0·5 in. diameter (6¾ oz. per foot) recently applied to St. Paul’s Cathedral.

Importance of perfect earth connection strongly insisted upon, but it is matter of some difficulty, and the oxidation of the earth terminals, and their inefficiency doubtless lead to most of the reported failures of lightning conductors. Author quotes Pouillet and Becquerel, as saying, that for the efficient discharge of the lightning, which could be carried by a copper rod 0·8 in. diameter, contact must be obtained with 1,200 square yards of moist earth, but this large requirement can only easily be obtained in towns by connection with the water mains. Various modes of obtaining adequate earth contact by iron harrows, Callaud’s grapnel in basket of coke, &c., described.

Explains the rationale of testing goodness of earth currents by the galvanometer. Calls attention to the destruction of upper terminals of conductors to factory chimneys by the emission of sulphurous fumes, and suggests that they might be cased in lead.

Calls attention to the importance of every joint being made absolutely perfect.

Urges the superiority of points for upper terminals, owing to their facilitating silent discharge, and rendering lateral discharges from the conductor less probable.

Thinks that multiple points of copper kept fairly sharp and clean are, on the whole, the best upper terminals.

Considers that all large masses of metal in a building should be connected with the conductor; but quotes M. Callaud, who holds the opposite view. Dr. Mann, however, points out that if the conductor be efficient and perfect, the accidents which M. Callaud contemplates, and on which he bases his arguments, could not occur.

Calls attention to the ready path afforded by the column of heated smoke discharged by chimneys, and hence alludes to the placing of a coronal conductor, as well as a multiple point on important chimneys.

Suggests the utilization of rain water pipes, by perfecting their joints, and securing a good earth connection at their base.

ON THE PROTECTION OF BUILDINGS FROM LIGHTNING. By R. S. BROUGH, 4to, MUSSOORIE, 1878.

(_Abstracted by W. H. Preece, C.E._)

A carefully prepared theoretical and practical paper, adapted for use in India. Author advocates the use of iron from its higher temperature of fusion, and greater specific heat than copper, its long protection from decay by galvanization and its cheapness. He prefers wire cables from the absence of joints in them. He gives precise instructions for the formation of a good earth, and advocates periodic electrical tests.

LIGHTNING CONDUCTORS. By Professors AYRTON and PERRY. (_Journal Society of Telegraph Engineers._ Vol. V., 1876, p. 412.)

(_Abstracted by W. H. Preece, C.E._)

The authors controvert Clark Maxwell’s views that a building would be perfectly protected from lightning by being enclosed in a network, or cage of wires, without the use of the earth. They object to the application of the laws of static electricity alone to such a case. Current induction intervenes, and this is not subject to the screening action of a cage. Hence, though a metallic cage may assist the protection of a house, it does not do so perfectly.

ON THE PROPER FORM OF LIGHTNING CONDUCTORS. By W. H. PREECE, C.E. (_British Association Report_, 1880).

(_Abstracted by G. J. Symons, F.R.S._)

Author states that ever since lightning conductors have been used, there have been disputes as to whether the discharge passes over the surface of conductors or through their mass. Snow Harris, Henry, Melsens, and Guillemin have held that it passed over the surface; Faraday held the opposite view.

The arguments in favour of the surface form are, in the opinion of the author, deductions from exploded theories, from imperfect experiments, or from erroneous interpretations of well ascertained facts. No direct experiments have ever been made to solve the question, as far as the author knows. Quantities of electricity, that is static discharges from condensers, are in incessant use for telegraphic purposes, and are found to follow exactly Ohm’s laws, even with the most delicate apparatus. The knowledge of the flow of electricity through conductors, of the retarding influence of electrostatic capacity upon this flow, and of the distribution of charge, has become so much greater of late years through the great extension of submarine telegraphy and the labours of Sir William Thomson, Clerk Maxwell, and others, that the author questions if any English electrician would now be found to argue in favour of the surface form. Nevertheless, as ribbons and tubes still continue to be used, and it appeared very desirable to settle the question experimentally, the author determined to try and do so.

_First Experiments, June 28, 1880._

Dr. Warren de la Rue, who is always ready to place his splendidly equipped laboratory at the service of science, not only allowed the author to use his enormous battery and his various appliances, but aided him by his advice, and assisted him in conducting the experiments.

Copper conductors, 30 feet long, of precisely the same mass, (_a_) drawn into a solid cylinder, (_b_) made into a thin tube, and (_c_) rolled into a thin ribbon, were first of all obtained. The source of electricity was 3,240 chloride of silver cells. The charge was accumulated in a condenser of a capacity of 42·8 microfarads. It was discharged through platinum wire of ·0125 diameter, of different lengths. The sudden discharge of such a large quantity of electricity as that contained by 42·8 mf. raised to a potential of 3,317[5] volts is very difficult to measure. It partakes very much of the character of lightning. In fact, the difference of potential per unit length of air is probably greater than that of ordinary lightning itself. It completely deflagrates 2½ inches of the platinum wire, but by increasing the length of the wire it could be made to reproduce all the different phases of heat which are indicated by the various shades of red until we reach white heat, fusion, and deflagration. Hence the character of the deflagration, which is (by its scattered particles) faithfully recorded on a white card to which the wire is attached, is a fairly approximate measure of the charge that has passed, while the length of wire, raised to a dull red heat, is a better one, for any variation in the strength of the current within moderate limits is faithfully recorded by the change of colour.

Footnote 5:

The electromotive force of the chloride of the silver cell is 1·03 volt.

Experiment 1.—Similar charges were passed through the ribbon, tube, and wire, and in each case 2½ inches of wire were deflagrated. No difference whatever could be detected in the character of the deflagration.

Experiment 2.—Ten inches of wire were taken and similar charges passed through. In each case the wire was raised to very bright redness, bordering on the fusing point, and in two cases the wire broke. In each case the wire knuckled up into wrinkles, and gave evidence of powerful mechanical disturbance. The same wire was not used a second time. No difference could be detected in the effect through the different conductors.

Experiment 3.—Silver wire of the same diameter and length was used, and similar charges transmitted through it. Redness was barely visible, but the behaviour of the wire was similar in each case.

The conclusion arrived at unhesitatingly was, that change of form produced no difference whatever in the character of the discharge, and that it depended simply on mass.

_Second Experiments, July 19, 1880._

As it might be urged that the length of conductor tested was so short, and its resistance so small that considerable variations might occur and yet be invisible, similar lengths (30 feet) of lead—a very bad conductor, its resistance being twelve times that of copper—were obtained, drawn as a wire, made as a tube, and rolled as a ribbon, each being of similar weight.

Experiment 4.—Charges from the same condenser, 42·8 mf., but with 3,280 cells, were passed through, and the discharges observed on 6 inches of platinum wire 0·0125 inch diameter, which in each case was heated to bright redness. No variation whatever could be detected, whether the wire, the tube, or the ribbon were used.

Experiment 5.—In order to form some idea as to how closely any variation in the character of the discharge could be estimated, a long piece of platinum wire was used, and the length adjusted until just visible redness was obtained; then a diminution of 10 per cent. (3 feet) produced a marked change to dull redness, and further excisions raised the temperature to brighter and still brighter red.

The conclusion arrived at was that any change in resistance of 5 per cent. would have been clearly and easily discernible.

It therefore appears proved that the discharges of electricity of high potentials obey the laws of Ohm, and are not affected by change of form. Hence, extent of surface does not favour lightning discharges. No more efficient lightning conductor than a cylindrical rod or a wire rope can therefore be devised.

ÉTABLISSEMENT DE LA FORMULE RELATIVE AU RAYON D’ACTION DES PARATONNERRES. Par EMILE LACOINE. (_L’Electricité_, October, 1880.)

(_Abstracted by G. J. Symons, F.R.S._)

This author gives a formula for determining the area protected, which he considers to vary with the height of the storm cloud, and the elevation of the ground. He states that the mean elevation of the storm clouds at Constantinople is as low as about 325 feet. He says that conductors placed near the extremities of a building have their radius of protection diminished, and therefore recommends a line conductor running round the building. (The _circuit des faites_ of the Paris Municipal Commission, see ante page 68).

He says that his formula leads to nearly the same results as have hitherto been adopted, but he gives three examples, the results of which are—length of conductor being 1·00, radius protected is respectively 3·80, 1·10, and 2·20.

ON THE SPACE PROTECTED BY A LIGHTNING CONDUCTOR. By W. H. PREECE, C.E. (_Phil. Mag._, Dec., 1880.)

(_Abstracted by G. J. Symons, F.R.S._)

In the early part of this paper the author discusses the distribution of electricity in the space between the storm cloud and the earth’s surface, and points out that the air in an electric field is in a state of tension or strain; and this strain increases along the lines of force with the electromotive force producing it until a limit is reached, when a rent or split occurs in the air along the line of least resistance—which is disruptive discharge, or lightning.

Since the resistance which the air or any other dielectric opposes to this breaking strain is thus limited, there must be a certain rate of fall of potential per unit length which corresponds to this resistance. It follows, therefore, that the number of equipotential surfaces per unit length can represent this limit, or rather the stress which leads to disruptive discharge. Hence we can represent this limit by a length. We can produce disruptive discharge either by approaching the electrified surfaces producing the electric field near to each other, or by increasing the quantity of electricity present upon them; for in each case we should increase the electromotive force and close up, as it were, the equipotential surfaces beyond the limit of resistance. Of course this limit of resistance varies with every dielectric; but we are now dealing only with air at ordinary pressures. It appears from the experiments of Drs. Warren de la Rue and Hugo Müller that the electromotive force determining disruptive discharge in air is about 40,000 volts per centimetre, except for very thin layers of air.

If we take into consideration a flat portion of the earth’s surface, and assume a highly charged thunder-cloud floating at some finite distance above it, they would, together with the air, form an electrified system. There would be an electric field; and if we take a small portion of this system, it would be uniform.

If the cloud gradually approached the earth’s surface, the field would become more intense, the equipotential surfaces would gradually close up, the tension of the air would increase until at last the limit of resistance of the air would be reached; disruptive discharge would take place, with its attendant thunder and lightning.

If the earth-surface be not flat but have a hill or a building, as A or B, upon it, then the lines of force and equipotential planes will be distorted, as shown in fig. 1. If the hill or building be so high as to make the distance HD equal to the limit of resistance (fig. 2), then we shall again have disruptive discharge.

If instead of a hill or building we erect a solid rod of metal, G H, then the field will be distorted as shown in fig. 2. Now it is quite evident that whatever be the relative distance of the cloud and earth, or whatever be the motion of the cloud, there must be a space _d d´_ along which the lines of force must be longer than _c c´_ or H D; and hence there must be a circle described around G as a centre which is less subject to disruptive discharge than the space outside the circle; and hence this area may be said to be protected by the rod G H. The same reasoning applies to each equipotential plane; and as each circle diminishes in radius as we ascend, it follows that the rod virtually protects a cone of space whose height is the rod, and whose base is the circle described by the radius G _c_. It is important to find out what this radius is.

Let us assume that a thunder-cloud is approaching the rod A B (fig. 3) from above, and that it has reached a point D´ where the distance D´ B is equal to the perpendicular height D´ C´. It is evident that if the potential at D´ be increased until the striking-distance be attained, the line of discharge will be along D´ C´ or D´ B, and that the length A C´ is under protection. Now the nearer the point D´ is to D the shorter will be the length A C´ under protection; but the minimum length will be A C, since the cloud would never descend lower than the perpendicular distance D C.

Supposing, however, that the cloud had actually descended to D when the discharge took place. Then the latter would strike to the nearest point; and any point within the circumference of the portion of the circle B C (whose radius is D B) would be at a less distance from D than either the point B or the point C.

“_Hence a lightning-rod protects a conic space whose height is the length of the rod, whose base is a circle having its radius equal to the height of the rod, and whose side is the quadrant of a circle whose radius is equal to the height of the rod._”

Upon this rule the author makes the following concluding remarks:

“I have carefully examined every record of accident that I could examine, and I have not yet found one case where damage was inflicted inside this cone when the building was properly protected. There are many cases where the pinnacles of the same turret of a church have been struck where one has had a rod attached to it; but it is clear that the other pinnacles were outside the cone; and therefore, for protection, each pinnacle should have had its own rod. It is evident also that every prominent point of a building should have its rod, and that the higher the rod the greater is the space protected.”

SHORT ACCOUNT OF THE STRIKING BY LIGHTNING OF THE RAILWAY TERMINUS AT ANTWERP, ON THE 10TH OF JULY, 1865. BY M. MELSENS, Member of the Royal Academy of Belgium.

(_Abstracted by R. Van der Broek._)

On the date mentioned, between three and four o’clock in the afternoon, a violent storm burst over Antwerp, during which the lightning struck the Railway Terminus, without, however, occasioning any other damage than the perforation of a single hole in one of the glass squares of the roof.

The author states that the effect of the discharge on this square of glass, which was about 4^{mm} (0·2in.) thick, was remarkable; it appeared as if it had been traversed by a projectile from below, the perforation, viewed from above, being broken and chipped, whilst viewed from below it showed a clean edge. The sinuosities caused by the chipping on the upper surface had rounded edges, and the glass appeared to have been subjected to incipient fusion. Not a single fragment of glass was found on the glass squares or in the gutters of the roof.

The author arrives at the following conclusions: The square of glass was pierced in the same manner as any square of similar nature and dimensions, placed in identical circumstances, would be, were it traversed by a spherical projectile fired at a low velocity from a firearm. The fracture resembled one that would be produced by a missile thrown from below, that is to say, from the earth to the sky.

The form of the opening indicated that the earth was positively electrified.

The author notices that, according to M. F. Duprez, negative electricity generally shows itself in abnormal conditions of the atmosphere, during storms, rains, &c., and when the wind blows from the western quarters between N. and S. Now, on the day in question, it rained and the wind blew from the west.

The author publicly thanks M. Ruhmkorff for his skilful and disinterested co-operation in proving the correctness of his (the author’s) view of the distribution of the electricity at the Antwerp discharge. M. Ruhmkorff has, at request, pierced squares of ordinary glass about 1^{mm} (0·04in.) thick by the discharge of his great induction apparatus charged by a powerful Leyden battery.

ON LIGHTNING PROTECTORS WITH POINTS, CONDUCTORS, AND MULTIPLE EARTH CONNECTIONS, A DETAILED DESCRIPTION OF THE LIGHTNING PROTECTOR ERECTED ON THE TOWN HALL OF BRUSSELS IN 1865, WITH AN ACCOUNT OF THE PRINCIPLES ADOPTED IN THE CONSTRUCTION, BY M. MELSENS, MEMBER OF THE ROYAL ACADEMY OF SCIENCES OF BELGIUM.

(_Abstracted by R. Van der Broek._)

As the author states in his preliminary observations that it is impossible to give a complete condensed description of the Lightning Protector, which he erected on the Town Hall at Brussels, we will merely draw attention to a number of facts, regarding the system followed, some of them, we believe, of a novel description.

M. Daniel Colladon, the author states, has observed that as a rule lightning does not strike a single part or prominent point of the objects that are struck or destroyed by it; and that, in the majority of cases, it does not strike in the form of a single spark, but in the form of a sheet with one or more principal centres of intensity. The correctness of this observation, the author considers fully borne out by the ravages which the electric discharge committed on the Town Hall at Brussels, on the 10th September, 1863. He gives an elaborate description of the effects of the flash on the building. It is interesting to note that the ravages principally took place at the side exposed to the west north-west wind, which was blowing at the time the building was struck.

In the ensuing winter the Municipal Council of Brussels took into consideration the necessity of protecting the Town Hall against a similar disaster, and the author was requested to superintend the erection of lightning protectors on the building.

The characteristics of the author’s system, as exemplified by the lightning protectors erected on the Brussels Town Hall, may be briefly summarised as follows:—

1. The points are very numerous—of three kinds; some long, sharp, and gilded, others of middling length, made of iron; and finally some small and very sharp, consisting of copper.

2. The points are replaced by _aigrettes_ (brushes of points diverging from a common base).

3. The conductor is not insulated.

4. The connections are simple and unchangeable, the joints are each embedded in a mass of zinc.

5. The surface exposed to the air is considerable.

6. The conductor consists of thin, and numerous wires, which are very flexible, so as easily to be led round all the corners of the buildings.

7. The conductor is made of galvanised iron.

8. The earth connections are multiple: firstly, a well within which a large surface of metal is plunged; and, secondly, two enormous networks of metal pipes, offering an immense contact surface with the earth. One of these networks is in direct communication with all the reservoirs and all the water sources of the environs of Brussels and also in indirect communication with two rivers and two canals.

The author has arrived at the conclusion that the height of the rod is a secondary question, as the radius of protection has not been determined by irrefutable proofs, and as that length is, in comparison with the distance and the extent of the thunder-clouds, so small a factor that it may safely be neglected. The author states that he has been greatly gratified to meet with the same opinion in a paper which Mr. W. H. Preece published in Vol. I., No. 3, page 366, of the Journal of the Society of Telegraph Engineers for 1872: “When we consider the distance of the cloud and the area of its surface, the height of a building vanishes in the general figure.”

The author points out that M. Perrot has endeavoured to demonstrate by experiment that the neutralizing area of a lightning protector surmounted by a crown of sharp points is far more extensive than that of an ordinary protector. M Perrott further thought, and MM. Babinet and Gavarret shared his opinion, that it is sufficient to shelter the ordinary protector from discharges of lightning by arming it with numerous, long, sharp, and well conducting divergent points. M. Gavarret after having repeated Mr. Perrott’s experiments, found the results so conclusive that he wrote to the author in the beginning of 1865: “It is at the present time no longer permitted to erect lightning protectors with single points.”

The metal of which the points are made must be a very good conductor. With regard to their conductivity, the metals follow each other in the following order: copper, silver, iron, platinum. No metals are used but those which resist fusion. The author rejected platinum and silver: the former because it fuses very readily by the electric discharge; and the latter, because it has, in his opinion, no advantage over copper.

The conductor, although galvanized, received several coats of paint; but the points (_aigrettes_) of course remained metallic. With regard to the general principle of connecting the protector with any masses of metal which may be about the building, the author has ever since 1865 endeavoured to demonstrate, that it is not sufficient, as might at first sight be supposed, to form that connection at one single point; there must be at least two points of contact, so as always to ensure a closed metallic circuit.

The contact with the water presents a surface of about ten square metres (12 sq. yds.), bringing both surfaces of the cylinder into account.

With regard to the earth connection, the author quotes M. Perrot, who remarks that with the ordinary protector the surface immerged offers a resistance at least 10,000 times greater than the conductor itself; it is therefore necessary to increase the surface of the earth-plate as much as possible.

In order to retard as much as possible the oxidation of the cylinder, the author introduced two hectolitres (6 bushels) of lime into the well, thus rendering the water alkaline.

DE L’APPLICATION DU RHE-ÉLECTROMÈTRE AUX PARATONNERRES DES TÉLÉGRAPHES. PAR M. MELSENS.

(_Abstracted by R. Van der Broek._)

In this pamphlet the author describes in § 1 an apparatus to show the presence of atmospheric electricity in telegraph wires.

In §§ 2 and 4 he explains how the apparatus is joined up in the Belgian telegraph offices.

§ 3 contains a résumé of observations made at the government telegraph offices between June, 1875, and March, 1876.

The author states in this paragraph that, on the 19th of June, 1875, the Rheo-Electrometer at the office at Louvain, showed a deflection of 85° East, although there was not the slighest appearance of atmospheric electricity. The fact was, that at the time a thunder storm was raging at Beverloo, distant from Louvain about 40 kilometres (25 miles).

TROISIÈME NOTE SUR LES PARATONNERRES. PAR M. MELSENS.

(_Abstracted by R. Van der Broek._)

On the 3rd of July, 1874, the church of Ste. Croix, at Ixelles, was struck by lightning. The building was provided with a lightning protector, which was constructed as follows: The point consisted of a platinum cone of about 30° (the form officially adopted in France in 1855), all the supports of the protector were soldered with zinc. This was attached to the steeple, and rose to 53 metres or 174 feet above the pavement. It consisted of an iron rod 18 mm. (0·71 in.) in diameter (M. E. Sacré’s system). The conductor passed from the principal roof along the roofs, descending to a point near a pump, behind the vestry, where the well (W) was situate. There is an abundance of water in the well, which is about 7 m. (23 ft.) deep. The conductor terminated in the well, by a cast-iron plate 0·65 m. (2 ft. 1 in.) by 0·50 m. (1ft. 8 in.), thus presenting a surface of 0·654 ⬜ m. (7 sq. ft.). A little in front of the transept there is a supplementary rod B 5·25 m. (17 ft. 3 in.) high, 11 m. (36 ft.) distant from the point (c in diagram) which was struck; and 22 m. (72 ft.) distant from that point there was a second rod D, whose height was 9 m. (29½ ft.) above the top of the roof.

The damage to the church was trifling, but the author contends that the fact of the church having been struck at all, proves that a building armed with a protector constructed on the usual principle is not completely protected.

A. Principal conductor on steeple. B. D. Two supplementary receiving rods. C. Stone cross at end of transept, which was struck, W. Well in which conductor made earth connection.

QUATRIÈME NOTE SUR LES PARATONNERRES. PAR M. MELSENS.

(_Abstracted by R. Van der Broek._)

This treats § 1 of observations on the distribution of the spark of electric batteries and machines over numerous metallic conductors of different sections, lengths, and nature, and on the passage of electricity of tension in bad conductors.

§ 2. Effects of soldered joints on the conductivity and the resistance of conductors. Interrupted lightning protectors.

§ 3. The distribution of sparks from Holtz’s machine and Ruhmkorff’s coil over two conductors outwardly identical, but one of iron and the other of copper. Comparative resistance to fusion and rupture for iron and copper conductors. Identical damage produced by discharges in several homogeneous and solid conductors.

APPENDIX G.

CATALOGUE OF WORKS UPON LIGHTNING CONDUCTORS, WITH A FEW UPON LIGHTNING, THUNDER, AND THE EFFECTS OF LIGHTNING STROKES, _Chiefly extracted from the_ RONALD’S CATALOGUE, _edited by Mr. Frost, but supplemented and brought down to 1880 by extracts from the Catalogues of_ R. ANDERSON, F.C.S.; LATIMER CLARK, C.E.; and G. J. SYMONS, F.R.S.

There are not many comments needed upon the following catalogue, but a few are necessary.

The arrangement is, with one exception, strictly alphabetical under author’s names; that exception being that all the Official Instructions issued in France are placed together at the beginning of the catalogue.

The initials =R=, =C=, =A=, =S=, are those of the Catalogues or Libraries in which the works are to be found; small type indicates that the title of the work is given in the catalogue indicated; large type that a copy of the book is in that Library. As Mr. Anderson does not state distinctly whether he possesses the books or has merely their titles, it has been thought safer to mark those taken from his catalogue with the small ¤A¤. The existence of any specified work in a certain library is absolute proof of the existence of the book, and hence the larger type has a certain value, and, besides that, I purpose, immediately after the publication of this Report, presenting to the Society of Telegraph Engineers all the Electrical works which are in my library but are not in the Ronald’s Library. It may therefore be assumed that most of the works to which a large type initial is prefixed are, or soon will be, in the splendid collections of the Society of Telegraph Engineers and Electricians.

The small figures in the front column show the pages of Appendix F, upon which abstracts of upwards of fifty of the following works will be found—and thus it forms an index to the works abstracted.

G. J. S.

OFFICIAL INSTRUCTIONS, FRANCE.

(_Abstracts of this series will be found on pages 51–69._)

=R= =S= │Instruction sur les Paratonnerres pour │ servir à l’Etablissement de ces Appareils │ au-dessus des Magasins à poudre, adoptée │ par le Comité des Fortifications dans sa │ Séance du 25 Août 1807: suivie des │ Rapports faits à ... l’Institut et à │ l’Académie des Sciences, sur cette │ Instruction et sur l’Etablissement des │ Paratonnerres en général. Fol. 39 pp. 1 │ plate. _Paris_, =1808= │ (This paper contains the reports by │ Franklin and others, dated 24th │ April, 1784; by Leroy and others, │ dated 27th December, 1799; and by La │ Place and others, dated 2nd November, │ 1807.) │ ¤R¤ │Instruction sur les Paratonnerres. Fol. _Paris_, =1823= │ =R= │Instruction sur les Paratonnerres adoptée │ par l’Académie, 23 April, 1823, (Signé) │ Poisson, Lefevre-Gineau, Dulong, Fresnel, │ et Gay-Lussac rapporteur. 4to. 51 pp. 2 │ plates. _Paris_, =1824= │ =S=│Instruction sur les Paratonnerres adoptée │ par l’Académie Royale des Sciences le 23 │ Juin, 1823. 8vo. 51 pp. 2 plates. _Paris_, =1824= │ =R= =S= │Supplément à l’Instruction sur les │ Paratonnerres, présenté par la section de │ physique. MM. Becquerel, Babinet, │ Duhamel, Despretz, Cagniard de Latour, │ Pouillet rapporteur. 4to. _Ext. des │ Comptes Rendus_, tom. xxxix. 112, and │ xl., Séance 18 Déc. 1854. _Paris_, =1854–5= │ =R= ¤S¤ │Instruction sur les Paratonnerres adoptée │ par l’Acad. des Sciences. 12mo. 130 pp. │ Cuts. _Paris_, =1855= │ =R= ¤S¤ │Instruction sur les Paratonnerres des │ magasins à poudre. Rapport lu 14 Janv., │ 1867. Commissaires Becquerel, Babinet, │ Duhamel, Vaillant, Pouillet, Fizeau, │ Regnault. 4to. 1 plate. 15 pp. (_Ext. des │ Comptes Rendus_, tom. lxiv. Séance 21 │ Janv. 1867.) _Paris_, =1867=. │ =S=│Instruction sur les Paratonnerres du Louvre │ et des Tuileries. (_Ext. des Comptes │ Rendus_, tom. lxvii. Séance 20 Juillet, │ 1868). 4to. _Paris_, =1868= │ ¤A¤ =S=│Instruction sur les Paratonnerres adoptée │ par l’Acad. des Sciences. Part I., 1823, │ M. Gay Lussac, rapporteur; Part II., │ 1854, and Part III., 1867, M. Pouillet, │ rapporteur. 12mo. _Paris_, =1874= │ Met. Soc.│Analyse des Rapports de M. de Fonvielle, à │ la suite de la mission qui lui avait été │ confiée en 1872, par M. Jules Simon, pour │ faire en Angleterre une enquête sur la │ foudre et les Paratonnerres. Fcap. fol. _Paris_, =1875= │ Met. Soc.│Analyse des Rapports des Architectes sur │ l’Etat des Fcap. fol. _Paris_, =1875= │ Met. Soc.│Instruction de la Commission chargée │ d’étudier l’établissement des │ paratonnerres des Edifices Municipaux de │ Paris, adoptée dans la Séance du 20 Mai, │ 1875. Fcap. fol. _Paris_, =1875= │ Met. Soc.│Résumé des expériences faites à │ l’Administration des Lignes │ Télégraphiques sur les parafoudres │ télégraphiques. Fcap. fol. _Paris_, =1875=

ANONYMOUS.

(_Arranged chronologically._)

¤S¤│Petit traité du tonnerre, esclair, foudre, │ gresle et tremblement de terre. 12mo. _Genève_, =1592= │ ¤S¤│Death of V. Tyrrell by Lightning and │ Preservation of Sir J. Rous. =1661= │ ¤S¤│Dreadful Storm of Thunder and Lightning, │ &c., at Bedford, August 19th. 4to. =1672= │ ¤S¤│Extraordinary Thunder and Lightning in the │ N. of Ireland, with the sad effects of │ the Fall of a Cloud. =1680= │ =R= │S——, Sir R. A Relation of the Effect of a │ Thunder-clap on the Compass of a Ship on │ the coast of New England. 3 pp. Also, a │ Letter concerning the former Relation. 2 │ pp. (_Phil. Trans. for_ 1683, xiii. pp. │ 520–21.) _London_, =1683= │ ¤S¤│Difesa della commune, ed antica sentenza │ che i fulmini discendano dalle nuvole │ contro l’opinione del S. Maffei, che si │ formino al basso, ed ascendano, etc. 4to. _Venezia_, =1749= │ =R= │Della maniera di preservare gli edificj dal │ Fulmine: Informazione al popolo, &c. 4to. │ 38 pp. (_Vide_ Toaldo.) At p. 20 is │ inserted a translation of Saussure’s │ Manifeste, entitled _Manifesto ossia │ breve esposizione dell’ utilità dei │ Conduttori elettrici_. _Venezia_, =1772= │ =R= │Della maniera di preservare ... dal │ Fulmine. 8vo. 22 pp. _Milano_, =1776= │ ¤R¤ │Neueste Versuche zur Bestimmung der │ zweckmässigsten Form der Gewitterstangen. │ (_Deutsch Mus._, Oct. 1778, pp. 351–62.) =1778= │ ¤R¤ │Encyclopædia Method. Arts. Article, │ Paratonnerre. =1782= │ ¤S¤│Accident by Lightning at Heckingham. 4to., │ plates. =1783= │ =R= │Nuovo metodo di costruire i Parafulmini │ praticato in Padova. 4to. 2 pp. │ (_Opuscoli Scelti_, vi. 380.) _Milano_, =1783= │ =R= │Dell’ efficacità dei conduttori elettrici, │ Dubbj proposti ai Fisici moderni. 8vo. =1784= │ =R= │Maniera pratica di fare li Conduttori 4to. │ (_Printed by order of the Magistrato │ della Sanità di Venezia._) (_Vide_ │ Marzari.) _Venezia_, =1787= │ ¤R¤ │Einige gegen die Gewitterableiter gemachte _Frankfort_, │ Einwürfe beantwörtet. 8vo. =1790= │ =R= │Dubbii sull’ Efficacia dei Conduttori. 8vo. │ 122 pp. 1 plate (_Vide_ Bragadin.) _Venezia_, =1795= │ ¤R¤ │Nachricht und Zeichnung von einer im Jahre │ 1778, am Schlossthurme, zu Dresden, │ angebrachten Ableitung. (_Schrift, d. │ Leipz. ökonomische Societät_, th. v. pp. │ 222–32.) │ =R= │Risposta dell’ autore dei Dubbii sull’ │ efficacia dei Conduttori, alla giunta al │ Giornale Astrometeorologico del Gr. │ Toaldo. (_Vide_ Bragadin.) │ =R= │Plain Directions for safe Lightning │ Conductors for Lightning. 8vo. 49 pp. │ _Note._—Part of a work. Begins at p. 33 │ ¤R¤ │Account of a mass of 7000 Bricks of a Wall │ displaced several feet by Lightning. 8vo. _Manchester, │ (_Manchester Memoirs_, ii. 2.) n.d._ │ ¤R¤ │Relazione del Turbine scoppiato in Venezia │ nel Giorno 16 Giugno, 1805. Data Venezia, │ 19 Giugno. 8vo. (_Da Rio Giornale_, ix. │ 266.) _Padova_, =1805= │ ¤R¤ │(R. R.) Death by Lightning. Man killed at │ Colwall, near Ledbury, 1817. 8vo. (_Phil. │ Mag._ 1. 315.) _London_, =1817= │ =R= │On Lightning Conductors of Straw. (_See_ │ Lapostolle.) =1820= │ =R= │On the Cure of a case of Paralysis by │ Lightning. 8vo. 2 pp. (_Phil. Mag._ lix. │ 287.) _London_, =1822= │ =R= │Remarks upon Mosely’s article on Solar │ Spots of 1816 in _Phil. Mag._ xlix. 182. │ 8vo. 3 pp. (_From New Monthly Mag. for │ January_, 1821. _At_ p. 72, _Chain Cables │ as Conductors_.) _London_, =1821= │ =R= │Anleitung zur Verfertigung und Benützung │ der Blizableiter. 8vo. 43 pp. 2 plates. │ (Translation of _French Official Report_ _Strasbourg_, │ of 1824, without name of Translator.) =1824= │ =R= │Tubes formed by Lightning. 8vo. 1 p. │ (_Phil. Mag._ or _Annals_, iv. 228.) _London_, =1828= │ ¤R¤ │Memoir on Lightning Conductors—Reply to a │ Prize Question. Bordeaux, 1837. (_Vide_ │ Bourges, Secretary of the Bordeaux _Bordeaux_, │ Academy, Séance 1837, p. 83.) =1837= │ ¤R¤ │On the knowledge of the Ancients concerning │ Lightning Conductors. 8vo. (_Fraser’s │ Magazine_, 1839?) _London_, =1839?= │ ¤R¤ │Sur l’Histoire du Paratonnerre, 1843. (_Le │ Portique_, 1^{re} livraison, Jan. 1843, │ p. 51.) =1843= │ =R= │Part of Bulletin des Mois de Mars, Avril., │ Mai, Juin, Juillet, Août, 1854. 8vo. │ (_Toulouse Acad._ series 4, vol. iv. At │ p. 483, De Clos, _Effets de la Foudre sur _Toulouse_, │ un Paratonnerre_.) =1854= │ ¤R¤ │De la Construction des Paratonnerres. │ Quelques Réflexions sur le Rapport de la │ Commission de l’Académie des Sciences du │ 14 Janvier, 1867. 8vo. 29 pp. _Paris_, =1868= │ │ =R= =S= │=Abbadie=, A. D’. Sur le tonnerre en │ Ethiopie. 4to. _Paris_, =1858= │ ¤R¤ ¤A¤ │=Achard=, F. K. Kurze Anleitung ländliche │ Gebäude vor Gewitterschäde sicher zu │ stellen. 8vo. _Berlin_, =1798= │ =R= │=Alden=, T., Jun. Effects of Lightning on │ the House of Captain Manning in │ Portsmouth, New Hampshire; in a letter to │ Dr. Eliot. 4to. 2 pp. (_Mem. Amer. _Cambridge, │ Acad._, iii. p. 93.) U.S._, =1809= │ =C= ¤A¤ │=Anderson=, R. Lightning Conductors: their =S= │ history, nature, and mode of application. (120) │ Large 8vo. _London_, =1879= │ =S=│ „ On the necessity for a regular │ Inspection of Lightning Conductors │ (_Brit. Ass. Rep._ 1880.) 8vo. _London_, =1880= │ =R= │=Arago=, F. Notices scientifiques. Sur la │ Grêle et des Paragrêles, &c. 12mo. _Paris_, =1827= │ =R= =C= │ „ Sur le Tonnerre. 12mo. ¤A¤ =S= │ _Paris_, =1837= │ =S=│ „ Ueber Gewitter. 12mo. _Weimar_, =1839= │ =R= ¤A¤ │ „ Meteorological Essays. Translated by =S= │ Sabine. 8vo. _London_, =1855= │ ¤A¤ │=Arnold.= Blitzableiter zum Schutz der │ Wärterbuden. _Polyt. Centralblatt._ 650. =1851= │ ¤A¤ │=Arrowsmith=, J. On the Use of Black Paint │ in averting the effects of Lightning on │ Ships. =1841= │ ¤R¤ │=Astier=, C. B. Notice sur les Paragrèles à │ pointes; projet de paragrèles à flammes │ et expériences comparatives du pouvoir │ électrique des flammes et des pointes. _Toulouse_, │ 8vo. =1829= │ =R= =S= │=Ayrton=, W, E., and =Perry=, J. Lightning (132) │ Conductors; an Answer to Prof. J. C. │ Maxwell’s suggestion to surround │ buildings with a conducting cage. (_Jour. │ Soc. Tel. Eng._, vol. v. p. 412.) _London_, =1876= │ │ │=Babinet.= (_See Official Instructions, │ France._) │ ¤R¤ │=Baier=, J. W. De Fulmine, fulgure, et │ tonitru hiemale. =1706= │ ¤R¤ │=Baldwin=, L. An Account of a very curious │ appearance of the Electric Fluid produced │ by raising a Kite in the time of a │ thundershower; in a Letter to J. Willard. │ 4to. (_Mem. Amer. Acad._ i. part ii. 257, │ old series.) _Boston_, =1785= │ =R= │ „ Observations on Electricity, and an │ improved mode of constructing │ Lightning-rods; in a letter to J. │ Willard. 4to. (Letter dated January 25, │ 1797.) (_Mem. Amer. Acad._ ii. part ii. _Charlestown, │ 96, old series.) U.S._, =1804= │ =R= ¤A¤ │=Barberet=, D. 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Tal on möjeligheten at │ förexomma askans skadeliga werkningar. _Stockholm_, │ 4to. =1764= │ ¤R¤ │ „ Rede von der Möglichkeit des Donners _Stockholm_, │ schädlichen Wirkungen vorzukommen. 4to. =1764= │ ¤R¤ │ „ Zusatz zu Vorhergehenden, _i.e._ │ Wilcke, Bemerkungen bei einem den 30 May, │ 1769.... Donnerschlage. 8vo. 5 pp. (_K. │ Akad. Schwed. Abh._ xxxii. 128.) _Leipzig_, =1770= │ ¤R¤ │=Bertholon=, de St. Lazare. Mémoire sur un │ nouveau moyen de se préserver contre la _Montpellier_, │ Foudre. 4to. =1777= │ ¤R¤ │ „ Lettre à M. de la Tourette, sur les │ Paratonnerres ascendants et descendants │ de la Ville de Lyon. (_Samml. zu Phys._ │ xix. _Mai_ 1782, p. 382.) =1782= │ ¤R¤ │ „ Nouvelles Preuves de l’efficacité des _Montpellier_, │ Paratonnerres. 4to. 28 pp. 3 plates. =1783= │ =R= ¤A¤ │ „ De l’Électricité des Météores. 2 vols. =S= │ 8vo. _Paris_, =1787= │ ¤R¤ =S= │ „ Die Electricität d. 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Bericht von zwei │ Blitz-Schlägen, welche das Schwedische │ Schiff Stockholms-Schloss in Ost-Indien, │ 1777, getroffen haben. 8vo. 14 p.p. │ (_Neue Schwedische Akademie Abhandlung_, │ i. 1780, p. 97) Translation. _Leipzig_, =1780= │ =C= │=Blagden & Nairne.= Proceedings relative to │ the Accident by Lightning at Heckingham. │ Report to Royal Society. (_Phil. Trans._) _London_, =1782= │ ¤A¤ │=Blesson.= Verbesserung an Blitzableitern. │ _Verhandl. des Vereins zur Beforderung │ des Gewerbefleisses in Preussen._ Jahrg. │ 1831, 250. =1831= │ ¤R¤ ¤A¤ │=Böckmann=, J. L. Ueber Blitzableiter. Eine ¤S¤ │ Abhandlung auf höchsten Befehl _Carlsruhe_, │ bearbeitet. Neue Auflage von Wucherer. =1830= │ ¤R¤ │ „ Ueber Blitzableiter. 3 Auflage von G. _Carlsruhe_, │ F. Wucherer. 8vo. =1839= │ =R= ¤A¤ │=Bodde=, J. B. 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Breve relazione degli effetti │ di un Fulmine che cadde in Napoli il mese │ di Giugno del presente anno 1774; e │ alcune considerazioni sopra i medesimi. │ 4to. 27 pp. _Napoli_, =1774= │ =R= =S= │=Boudin=, M. Histoire physique et Médicale │ de la Foudre, et de ses effets sur │ l’homme, les animaux, les plantes, les │ édifices, les navires. 8vo. 31 pp. (_Ext. │ Annales d’Hygiène, &c._) _Paris_, =1854= │ =R= │ „ De la Foudre considérée au point de │ vue de l’Histoire, de la Médecine légale, │ et de l’Hygiène publique. 8vo. 50 pp. _Paris_, =1855= │ =R= │ „ Histoire de la Foudre et des │ Paratonnerres. 8vo. 57 pp. cuts. (_Ext. │ Annales d’Hygiène._) _Paris_, =1855= │ ¤R¤ │=Bourges.= Rapport sur les travaux de │ l’Académie, Séance 1837, 22 Sept. 8vo. │ (_Séances de l’Académie de Bordeaux pour _Bordeaux_, │ 1837_, p. 83.) =1837= │ _Note._—Contains notices of two │ memoirs, as replies to a prize │ question on Lightning-conductors. The │ first is an anonymous one, which │ speaks of the forms of roofs and of │ metallic masses spread over the │ edifice, &c. The second is by Mermet, │ of Pau, who received a gold medal, │ but not the prize. │ =R= │=Bragadin= (or Anonymous). Dubbii sull’ │ efficacia de’ Conduttori elett. 8vo. 122 │ pp. 1 plate. _Venezia_, =1795= │ =R= │ „ Risposta dell’ autore dei Dubbii sull’ │ efficacia dei Conduttori, alla giunta al │ Giornale Astrometeorologico del ... │ Toaldo. 8vo. 31 pp. │ ¤S¤│=Braun=, A. A. Ueber zwei am 26 Juli bei │ Berlin v. Blitz getroff. Eichen. _Berlin_, =1869= │ ¤R¤ │=Breitinger=, D. Reflexionen ob es wohl │ gerathen wäre, Strahlenableiter in │ unserer Stadt Zürich einzuführen. _Zurich_, =1776= │ ¤R¤ │ „ Nachricht über das Einschlagen des │ Blitzes in einen Wetterableiter, nebst │ Berichtigung einiger Begriffe über die │ Wirkung der Ableiter. _Zurich_, =1786= │ =R= │=Breitinger=, D. Ragguaglio d’un Fulmine │ caduto in un Conduttore. 4to. 3 pp. │ (_Opuscoli Scelti_, ix. 210.) _Milano_, =1786= │ ¤R¤ │ „ Instruction für diejenigen, welche │ sich mit der Verfertigung und Visitation │ der Blitzableiter beschäftigen. _Zürich_, =1825= │ ¤R¤ ¤A¤ │ „ Instruction über Blitzableiter im │ Canton Zürich. 4to. _Zurich_, =1830= │ =R= │=Brewster=, Sir D. On the Life Boat, the │ Lightning-conductor, and the Light-house. │ 8vo. (_North British Review_, xxxii. 492, │ November, 1859.) =1859= │ ¤A¤ │=Bright=, E. B. Lightning Conductors. │ (_Mech. Mag._, lix. 246.) =1853= │ =R= =S= │=Brook=, A. Miscellaneous experiments and │ remarks on Electricity 4to. _Norwich_, =1789= │ =C= │=Brooks=, D. Facts and inferences relating │ to Lightning and Lightning Rods. 8vo. 16 _Philadelphia_, │ pp. =1872= │ ¤A¤ │ „ Lightning and Lightning Rods. │ (_Journal of the Franklin Institute._) │ lxvi. 4. =1873= │ (117) =S=│ „ Atmospheric electricity. 8vo. _Philadelphia_, │ =1878= │ (132) =S=│=Brough=, R. S. Protection of Buildings _Mussoorie_, │ from lightning. 4to. (_Lithographed._) =1878= │ =C= │=Brown=, R. Disputatio Philosophica De _Trajecti ad │ Fulmine. 4to. 16 pp. Rhenum_, =1692= │ (89) =S=│=Buchanan=, G. An account of the chimney of │ the Edinburgh Gas Works. 8vo. (_Proc. _Edinburgh_, │ Roy. Scot. Soc. Arts._) =1851= │ ¤R¤ ¤S¤ │=Buchenau=, F. Mittheilungen über einen │ interressanten Blitzschlag in mehreren │ Stieleichen. 4to. 15 pp. _Dresden_, =1867= │ ¤R¤ │=Bucher.= Einige gegen die Gewitterableiter _Frankfort_, │ gemachte Einwürfe beantwortet. 8vo. =1790= │ =R= ¤A¤ │=Buchner=, O. Die Construction und Anlegung =S= │ der Blitzableiter. zum Schutze aller (128) │ Arten von Gebäuden, Seeschiffen, and │ Telegrafenstationen; nebst │ Kostenvoranschlägen. 8vo. 152 pp. mit │ einem Atlas von 6 Foliotafeln. _Weimar_, =1867= │ =S=│ „ De bliksemafleiders, door C. J. v. │ Doorn. 8vo. _Haarlem_, =1867= │ ¤A¤ │ „ Die Construction. 8vo. 2nd Ed. 8vo. _Weimar_, =1876= │ ¤R¤ │=Buissart.= Mémoire sur les divers │ Avantages qu’on pourroit retirer de la │ Multiplicité des Conducteurs Electriques, │ ou Paratonnerres. Lu à l’Acad. d’Arras. │ 24 Avril, 1781. (_Saumlez, Phys. │ Supplem._ 1782. xxi. pp. 140–48) =1782= │ ¤R¤ │ „ Mémoire juridique sur les Conducteurs │ Electriques. (From _Van Swinden_, p. 137; │ _Van Troostwyk and Krayenhoff_, p. 241.) │ ¤A¤ │=Bunsen=, J. Versuch, wie die Meteora des │ Donners und Blitzes des Aufsteigens der │ Dünste, incl. des Nordscheins, aus │ elektr. Versuchen, herzuleiten und zu │ erklären. 8vo. _Lemgo_, =1753= │ =R= │=Burnaby=, A. Voyages dans l’Amérique │ Septentrionale, Traduit de l’Anglais. _Lausanne_, │ (Conductors melted by Lightning.) =1778= │ ¤S¤│=Burt.= Miscellaneous Scientific papers. =1861–65= │ =R= │=Busse=, F. G. von. Beruhigung über die │ neuen Wetterableiter. 8vo. 62 pp. _Leipzig_, =1791= │ ¤R¤ │ „ Beschreibung einer wohlfeilen und │ sichern Blitzableitung, mit neuen Gründen │ und Erfahrungen. 8vo. 1 plate. _Leipzig_, =1811= │ ¤R¤ ¤A¤ │=Butschany=, M. Dissertatio de Fulgure et │ Tonitru ex Phænomenis Electricis. 4to. _Göttingen_, │ pp. 1 et 2. (_Poggendorf_, i. 353.) =1757= │ ¤R¤ ¤A¤ │ „ Der Blitz entsteht nicht durch │ Entzündung einiger brennbaren Theilchen │ die in der Luft schweben, und ist auch │ kein Feuer. (_Beitrage zu Hannov. │ Magazin_, 1761.) _Hanover_, =1761= │ ¤R¤ │ „ Eine Unvollkommenheit der │ Blitzableiter, nebst ihrer Verbesserung. │ 8vo. (From _Poggendorff_, i. 353.) _Hamburg_, =1787= │ │ │=Cagniard de Latour.= (_See Official │ Instructions, France._) │ =C= ¤A¤ │=Callaud=, A. Traité des Paratonnerres. =S= │ Large 8vo. (103) │ _Paris_, =1874= │ ¤R¤ │=Camerer=, J. W. Über das Einschlagen des │ Gewitters auf zwei mit Blitzableitern │ versehenen Häusern. (_Tubing.-Blätter_, │ 1815, Bd. ii.) _Tubing_, =1815= │ ¤R¤ ¤A¤ │=Cardanus=, G. De fulgure. Liber unus. Fol. │ (_Cardani Geronimo Opera omnia._ 10 vols, │ folio, vol. ii.) _Lugd._ =1663= │ ¤R¤ │=Castelli=, C. Dissertazione sull’ origine │ delle straordinarie meteore dell’ anno │ 1783, e sulla maniera d’ impedire i │ fulmini e le grandini. 8vo. (_From MS. │ Catalogue, Padua Academy._) _Milano_ │ =R= A S │=Cavallo=, T. A complete Treatise on _London_, =1777, │ Electricity. 8vo. (_Many editions._) &c=. │ ¤R¤ │=Cerini=, G. Impossibilità fisico-chimica │ del paragrandine. _Milano_, =1821= │ ¤R¤ │=Chamberlayne=, J. On the effect of Thunder │ and Lightning at Stampford Courtney, in │ Devonshire. 4to. (_Phil. Trans._ 1712.) _London_, =1712= │ ¤A¤ │=Chantrel=. Ueber Blitzableiter. (_Polyt. │ Journ._, lxxxvi. 179.) =1842= │ (70) =S=│=Chapman=, Sir F. E. Instructions as to the │ application of Lightning Conductors. 8vo. │ (_Army Circulars._) =1875= │ ¤R¤ │=Chappe=, D’Auteroche. Observations sur │ l’orage du 6 Août, 1767, et d’un coup de │ foudre qui s’est élevé de la terrasse de │ l’Observatoire. 4to. (_Mém. de Paris_, │ 1767, _Mém._ p. 344.) _Paris_, =1767= │ =R= │ „ Voyage en Californie pour │ l’Observation de Vénus sur le disque du │ Soleil le 3 Juin, 1767.... Redigé et │ publié par M. Cassini fils. 4to. 170 pp. │ 4 plates. =S= │(_On Lightning (as ascending)_, p. 31, _and │ reference to the same subject in his │ Voyage en Sibérie_). _Paris_, =1772= │ ¤R¤ │ „ Voyage en Sibérie. (_Pogg._ i. 420, │ _says_ 3 vols. 4to.) _Paris_, =1763= │ ¤R¤ │=Chevallier=, J. G. Instruction sur les │ paratonnerres. _Paris_, =1823= │ ¤R¤ │=Chigi=, A. Lettera ad un amico sopra il │ Fulmine caduta, 18 Aprile, 1777, nella │ spranga.... torre del Palazzo.... di │ Siena. _Siena_, =1844= │ =R= │=Chiminello=, V. Risposta ... al commento │ ... nel Giornale Astrometeorologico, │ 1806, del Sig. G. Scaguller, 12mo. 24 pp. │ (_On Lightning Conductors._) _Venezia_, =1806= │ ¤R¤ │ „ Precauzione d’applicare il secondo │ conduttore ovvero l’Emissario per │ preservare gli edifizii dai Fulmini. │ (_Giornale Astrometeorologico_, 1806.) _Padova_, =1806= │ =R= │=Chinale= e Compa. Paragrandine. │ Istruzione. 8vo. 25 pp. 1 plate. │ (_Estratti del Propagatore._) _Torino_, =1828= │ =R==C==S=│=Clark=, Latimer. On the Storms experienced │ by the Submarine Cable Expedition in the │ Persian Gulf, 1869. (_Jour. Met. Soc._) │ 8vo. _London_, =1873= │ ¤R¤ │=Clerc.= Compte-rendu. 1er Sémestre de │ 1819. 8vo. (_Lyon’s Acad. │ Comptes-rendus._) _Lyon_, =1819= │ =Note.=—Mention of a work received from │ le Comte de Lezai-Marnesia ... sur │ les Paratonnerres et les │ Paragrêles—N. D. │ =R= │=Close=, D. Passage d’une letter ... sur │ les effets de la Foudre sur la chaîne du │ paratonnerre d’un vaisseau. 8vo. 2 pp. │ (_Toulouse Acad._ 4e série, tome iv. p. _Toulouse_, │ 483.) =1854= │ =R= │=Cohn=, F. Ein interessanter Blitzschlag │ beschrieben. 4to. 2 plates. (_Acad. │ Leop._ 1856, vol. xxvi. part i. p. 177.) =1856= │ │ „ Die Einwirkung des Blitzes auf Bäume. │ 4to. (_Acad. Leop.?_) │ ¤S¤│=Colladon=, D. Mémoire sur les effets de la │ Foudre sur les arbres et les plantes │ ligneuses, et l’emploi des arbres comme │ parratonnerres. to. _Genève_, =1872= │ (117) =S=│=Collin= et Fils. Paratonnerres. (_Extract │ from Catalogue._) 4to. │ ¤R¤ │=Collinder=. De fulguribus. 4to. (_From │ Watts._) _Upsal_, =1686= │ =R= │=Contessi=, M. Disquisizione sui │ paragrandini. 4to. 26 pp. _Treviso_, =1826= │ =R= │=Costantini=, G. A. (?) Difesa della ... │ Sentenza che i Fulmini discendono dalle │ nuvole ... Riflessioni. 4to. 184 and 12 _Venezia_, │ pp. =1749=. │ =R= │=Cowper.= (Poet.) Letter to Tilloch, from │ J. S. S., containing an Extract from the │ 3rd vol. p. 178, in a letter to the Rev. │ John Newton, of Cowper’s Correspondence │ as published by Hayley. This extract │ contains an account of two Fireballs │ which burst “_on the steeple, or close to │ it_,” at Olney. 8vo. (_Phil. Mag._ xix. │ 296.) _London_, =1804= │ ¤R¤ │=Crause= (Krause), R. W. De fulmine tactis. _Jenæ_, =1694= │ ¤R¤ │=Crœse=, G. De Fulmine. 4to. (_From _Amsterdam_, │ Watts._) =1659= │ =R= =S= │=Crosse=, A. Memorials of the late. 8vo. _London_, =1857= │ │ │=D’Abbadie.= (_See Abbadie, D’._) │ ¤A¤ │=Dalibard=, M. Histoire abrégée de │ l’Electricité. 2 vols. 8vo. _Paris_, =1766= │ │=D’Auteroche.= (_See Chappe D’Auteroche._) │ =R= │=Davies=, E. An account of what happened │ from Thunder in Carmarthenshire; partly │ from the woman’s mouth that suffered by │ it, partly from what was observed by │ others; communicated to the Royal Society │ by Eames J., as he received it in a │ letter from Davies E., dated Pencarreg, │ Saturday, Dec. 6, 1729–30. 4to. 5 pp. _London_, │ (_Phil. Trans._ xxxvi. 444.) =1729–30= │ =R= │=Daviet de Foncenex=, F. 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Franklin to D. │ Hume, Esq., on the method of securing │ houses from the effects of Lightning. _Edinburgh_, │ 8vo. 15 pp. =1771= │ =R= ¤C¤ │ „ Experiments and Observations. (_5th =S= │ edition._) 4to. (79) │ _London_, =1774= │ ¤A¤ │=Franklin=, B. Experiments on the Utility │ of long-pointed Rods for securing │ Buildings from damage by Strokes of │ Lightning. _London_, =1779= │ =R= =S= │ „ Mémoire sur la manière d’armer d’un │ conducteur la cathédrale de Strasbourg et │ sa tour. 8vo. =1780= │ Entered in the Ronald’s Catalogue, │ under Barbiere de Tinan, but issigned │ by Franklin. │ (_See Official Instructions, France._) │ ¤R¤ │=Frecksel.= Bemerkungen über Blitzschläge. =1819= │ =R= │=Frost=, A. J. Catalogue of books and =C==S= │ papers relating to Electricity, &c., │ compiled by Sir Francis Ronalds, F.R.S. │ 8vo. xxvii. 564 pp. _London_, =1880= │ =R= =S= │=Fremery=, N. C. De. Dissertatio philos, _Lugd. 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Kurze Anleitung, │ auf welche Art Blitzableiter an d. │ Gebäuden anzubringen sind. 8vo. 3 plates. _Berlin_, =1798= │ ¤R¤ │ „ Kurze Anleit. &c. (Blitzableiter). │ 8vo. 3 plates. _Berlin_, =1802= │ ¤R¤ │ „ Kurze Anleit, &c. 3e Aufl. 8vo. _Berlin_, =1819= │ │=Gineau.= (_See Official Instructions, │ France._ ) │ ¤R¤ │=Giorgi=, E. Ueber Blitzableiter. (_Vide │ Majocchi Annali_, viii. 178.) │ =S=│=Gray=, J. W. & Son. Lightning, its │ destructive action on buildings. 8vo. _London_, =1875?= │ ¤R¤ │=Green=, W. P. Selection of papers on the │ subject of fixed Lightning Conductors to │ the masts of H.M.’s Navy, constructed so │ as to pass from the truck to the keelson │ ... illustrated by engravings, &c. 8vo. _London_, =1824= │ ¤R¤ │ „ On Lightning Conductors for Ships. =1828= │ ¤S¤│ „ Precautions to avoid accidents by │ Lightning. 8vo. =1837= │ ¤R¤ │=Greimble.= Dissertatio physica de genu _Agust. Vind._ │ progressu et effectibus fulminis. 12mo. =1759= │ ¤A¤ │=Grenet=, E. Construction des │ Paratonnerres. 8vo. _Paris_, =1873= │ ¤R¤ │=Grimm=, J. Über die Namen des Donners. │ Eine academische Abhandlung vorgelesen am │ 12 Mai, 1853. 4to. 28 pp. _Berlin_, =1855= │ =R= ¤A¤ │=Gross=, J. F. Grundsätze der │ Blitzableitungskunst geprüft, und durch │ einen merkerwürdigen Fall erläutert. Nach │ dem Tode des Verfassers herausgegeben von │ J. F. W. Widenmann. 8vo. 228 pp. 1 plate. _Leipzig_, =1796= │ =R= │=Guazzi=, A. Transunto del Ragguaglio d’un │ Fulmine caduto presso Casalmaggiore con │ danno di tre persone. 4to. 3 pp. (_Opusc. │ Scelt._ xiv. 301.) _Milano_, =1791= │ =R= │=Guden=, P. P. Von der Sicherheit wider die _Göttingen_, │ Donnerstrahlen. 8vo. 200 pp. =1774= │ =R= │=Gutle= und =Luz=. Unterricht vom Blitz und │ den Blitz-und-Wetter Ableitern, zur │ Errinerung und Beruhigung sonderlich der │ ungelehrten, und des gemeinen Mannes von │ F. Luz neu bearbeitet von J. K. Gutle. _Nürnberg_, │ Erster Theil. 8vo. 222 pp. 1 plate. =1804= │ =R= │=Gutle=, J. C. Lehrbuch der praktischen │ Blitzableitungskunst ... als Fortsetzung │ der “Theoretischen Blitzableitungslehre.” _Nürnberg_, │ 8vo. 446 pp. 16 plates. =1804= │ ¤R¤ ¤A¤ │ „ Algemeine Sicherheitsregeln für _Nürnberg_, │ Jederman bey Gewitter. 8vo. =1805= │ =R= │ „ Fasslicher Unterricht wie man sich bei │ Gewittern vor den ... Wirkungen des │ Blitzes ohne Blitzableiter sicher ... _Nürnberg_, │ verwahren kann. 8vo. 140 pp. =1805= │ =R= ¤A¤ │ „ Neue Erfahrungen über die beste Art _Nürnberg_, │ Blitzableiter anzulegen. 8vo. =1812= │ ¤R¤ │ „ Neue wissenschaftliche Erfahrungen, │ Entdeckungen und Verbesserungen, &c. 8vo. │ 272 pp. 4 plates. _München_, =1826= │ │ ¤R¤ │=Hachette=, J. N. P. Sur la formation des │ tubes fulminaires. 8vo. (_Ann. de Chim._ │ xxxvii. 1828.) _Paris_, =1828= │ =R= │=Haidinger=, W. Ritter Von. Niedrigste │ Höhen von Gewitterwolken (Zwei Fälle in │ Erinnerung gebracht.) 8vo. 10 pp. (_Aus │ den Sitzungsberichten_ 1852, _der k. │ Akad. der Wissenschaften abgedruckt._ │ Vol. ix. ii. Heft.) _Wien_, =1853= │ =R= ¤S¤ │ „ Die südwestlichen Blitzkugeln am 20 │ Octbr. 1868. Nachtrag zu der Mittheilg. │ am 5 Novbr. 8vo. 2 pp. (_Sitzb. d. k. │ Akad. d. Wiss._ Dec. Heft. 1868 lviii. │ Bde.) _Wien_, =1868= │ =R= ¤S¤ │ „ Ein kugelförmiger Blitz am 30 Aug. │ 1865, gesehen zu Feistritz bei Peggau in │ Stiermark. 8vo. 4 pp. (_Sitzb. d. k. │ Akad. d. Wiss._ Dec. Heft. 1868, lviii. │ Bde.) _Wien_, =1868= │ =S=│=Hajingi=, B. ΚΕΡΑΥΝΟΛΟΓΙΑ ΦΥΣΙΚΗ, Seu _Giessæ │ Disquisitio de Fulmine Naturalis. 4to. Hassorum_, =1660= │ =R= │=Hallencreutz=, D. Beobachtung an │ Gewitterwolken welche Blitze gegen │ einander geben zu Pello innerhalb des │ Polarkreises. 8vo. 3 pp. 1 plate. (_K. │ Schwed. Akad. Abh._ xxxv. 85.) _Leipzig_, =1773= │ ¤R¤ │=Halley=, E. Observation sur les coups de │ Tonnerre multipliés et extraordinaires. │ 4to. (_Mém. de Paris_, 1731. _Hist._ p. │ 19.) _Paris_, =1731= │ =S=│=Hamberg=, H. E. Om den s. k. │ luftelektriciteten. 8vo. _Upsala_, =1872= │ ¤R¤ │=Hannemann=, J. L. De fulminis effectu │ miro. (_Miscell. Acad. Nat. Cur._) =1685= │ ¤A¤ │=Hare=, R. Ueber die Ursachen, warum │ Wetterableiter in einigen Fällen nicht │ schützen, und die Mittel dieselben │ vollkommen schützend zu machen nebst │ einer Widerlegung der herrschenden Idee │ dass Metalle die Elektricität vorzüglich │ anziehen. Aus. Gill’s Technological │ Repository, Nov., 1827, im _Polyt. │ Journ._, xxvii. 268. =1828= │ ¤R¤ │=Harris= (afterwards Sir), William Snow. │ Electrical Conductors for Ships. │ Experiment in Plymouth Harbour. 8vo. 7 │ pp. (_Phil. Mag._ lx. 231.) _London_, =1822= │ =R= ¤C¤ │ „ Observations on the effects of ¤A¤ ¤S¤ │ Lightning on floating bodies, &c., with │ an account of a new method of applying │ fixed and continuous Conductors of │ Electricity to the Masts of Ships. Letter │ to Sir T. B. Martin. 4to. 89 pp. 5 │ plates. _London_, =1823= │ _Note._—The illustration accompanies │ plate i. The lines on the paper │ originally consisted of gold leaf.... │ A discharge has been passed over the │ gold leaf to show by its deflagration │ the course of the electric matter. │ =R= │ „ On the relative powers of various │ metallic substances as Conductors of │ Electricity. Read Dec. 14, 1826. 4to. 7 │ pp. 1 plate. (_Phil. Trans._) _London_, =1827= │ =R= ¤A¤ │ „ On the utility of fixing Lightning _Plymouth_, │ Conductors on Ships. 8vo. 23 pp. =1830= │ =R= │ „ A series of papers on the defence of │ Ships and Buildings from Lightning. 8vo. │ 46 pp. (_Nautical Magazine_, xxv.) _London_, =1835= │ =R= ¤S¤ │ „ Inquiries concerning the elementary │ laws of electricity. 4to. _London_, =1836= │ ¤R¤ │ „ A series of three Papers, termed │ Illustrations of cases of damage by │ Lightning in the British Navy. (_Nautical │ Magazine_ for 1838.) _London_, =1838= │ ¤A¤ │ „ On the Protection of Ships from │ Lightning. (_Annals of Electricity_, ii. │ 81.) =1838= │ =R= ¤S¤ │ „ State of the question relating to the │ protection of the British Navy from │ Lightning, by the method of fixed │ Conductors of Electricity, as proposed by _Plymouth_, │ Mr. Snow Harris. With appendix. 8vo. =1838= │ ¤C¤ ¤S¤│ „ History of 220 ships struck by │ Lightning. =1839= │ =R= ¤A¤ │ „ On Lightning Conductors, and on │ certain principles in Electrical science; │ being an investigation of Mr. Sturgeon’s │ experimental and theoretical researches │ in Electricity, published by him in the │ _Annals of Electricity_, &c. 8vo. 12 pp. │ 1 plate. (_Phil. Mag._ for Dec., 1839, p. │ 463.) _London_, =1839= │ =R= =S= │ „ Copy of the report and evidence from (83) │ the Commission appointed to inquire into │ the plan of W. S. Harris, relating to the │ protection of Ships from the effects of │ Lightning. Ordered by the House of │ Commons to be printed, 11th Feb., 1840. │ Folio. 96 pp. 12 plates. _London_, =1840= │ ¤S¤│ „ State of the question relating to the │ protection of the British Navy. 8vo. =1840= │ ¤R¤ │ „ On the course of the Electrical │ discharge, and on the effects of │ Lightning on certain ships of the British │ Navy. 8vo. (_Edinb. and Lond. Phil. │ Mag._, Feb. and March, 1840.) _London_, =1840= │ =R= │ „ On Lightning Conductors, and the │ effects of Lightning on H.M.’s ship │ “_Rodney_” and certain other ships of the │ British Navy; being a further examination │ of Mr. Sturgeon’s Memoir on Marine │ Lightning Conductors. 8vo. 12 pp. 1 │ plate. (_Annals of Electricity_, iv. │ 484.) _London_, =1840= │ ¤R¤ │ „ On the supposed Electro-magnetical │ effects of Marine Lightning Conductors. │ (_Nautical Magazine_, Enlarged Series, │ No. 2, vol. for 1841) =1841= │ ¤R¤ │ „ Observations on the action of │ Lightning Conductors. (_Proc. London │ Elec. Soc._ for 1842.) _London_, =1842= │ =R= │ „ On the effects of Lightning on the │ British ship “_Underwood_,” 8vo. 8 pp. │ (_Nautical Mag._ for June, 1842.) _London_, =1842= │ =R= ¤C¤ │ „ On the nature of Thunderstorms, and ¤A¤ =S= │ the means of protecting Buildings and (85) │ Shipping against ... Lightning. 8vo. _London_, =1843= │ ¤R¤ │=Harris=, W. S. A theoretical and practical │ view of Thunderstorms, and the protection │ of Buildings and Ships from Lightning. _London_, =1843= │ =R= │ „ On Damage by Lightning in the British │ Navy. 8vo. 66 (pp. _Extract from the │ Nautical Magazine_, 1843.) _London_, =1843= │ ¤S¤│ „ Brief history of 220 Ships. 8vo. 1844 │ =R= ¤S¤ │ „ Meteorology of Thunderstorms at Sea, │ with analytical deductions; and a history │ of the effects of Lightning on 210 ships │ of the Royal Navy. 8vo. _London_, =1844= │ _Note._—The first part was printed in │ the “Nautical Magazine” after the │ second part, containing the history │ of cases, had been completed. The │ first part has 18 pp.; the second │ part is entitled, “Damage by │ Lightning in the British Navy,” and │ has 66 pp. │ =R= │ „ Remarkable instances of the protection │ of certain Ships of H.M.’s Navy from the │ destructive effects of Lightning; │ collected from various authorities. 8vo. _Plymouth_, │ 18 pp. =1844= │ ¤R¤ │ „ Remarkable instances of defence of │ certain Ships of the Royal Navy from the │ destructive agency of Lightning, with │ practical and theoretical deductions. _London_, =1846= │ ¤R¤ │ „ Letter to the Secretary of the │ Incorporated Society for Building │ Churches, &c., on the Preservation of _Plymouth_, │ Public Buildings from Lightning. 8vo. =1847= │ ¤R¤ │ „ A Public Official Letter to the India │ Board, dated June 21, 1847, relative to a │ Board Order requiring all Transports to │ be fitted with his Conductors. =1847= │ ¤S¤│ „ History of 220 ships of the Royal │ Navy. 8vo. =1847= │ =R= │ „ Remarkable instances of the protection │ of certain Ships ... from the destructive │ effects of Lightning. 8vo. 61 pp. 2 │ plates. _London_, =1847= │ ¤R¤ ¤S¤ │ „ Instructions for the application of │ permanently fixed Conductors in H.M.’s │ ships, drawn up for the use of H.M.’s │ dockyards. Printed by order of the Lords │ Commissioners of the Admiralty. _London_, =1848= │ =R= │ „ Letter to the Earl of Wilton on │ returns ... relative to ... fixed │ Metallic Conductors employed in H.M.’s _Plymouth_, │ Navy. 8vo. 35 pp. =1849= │ =R= │ „ Letter on the Preservation of Public │ Buildings from ... Lightning (revised) │ addressed to the ... Society for building │ Churches, &c., dated December, 1847. 8vo. │ 12 pp. _London_, =1850= │ =R= ¤S¤ │ „ On the relative Cost and Efficiency of │ permanent and temporary forms of │ Lightning Conductors as applicable to the _Plymouth_, │ defence of the Royal Navy. 8vo. 27 pp. =1850= │ =R= │ „ Remarkable instances of the │ Preservation of certain Ships of the │ Royal Navy from Lightning. Abridged from │ Official and other authenticated Reports. _Plymouth_, │ 8vo. 19 pp. =1850= │ =R= │ „ Destruction of Merchant Ships. │ Shipwreck by Lightning. 8vo. 6 pp. │ (_Nautical Magazine_ for November, 1852.) _London_, =1852= │ =R= │ „ Papers relating to Harris’s Lightning │ Conductors and the destructive effects of │ Lightning on Ships. Fol. 11 pp. 2 plates. _London_, =1852= │ =R= │ „ Papers relative to Harris’s Lightning │ Conductors, Appendix, with Addendum of 1 │ sheet. Fol. 37 pp. _London_, =1852= │ =R= │ „ Review of the History and Progress of │ the general system of Lightning │ Conductors ... in the Royal Navy. 8vo. 10 │ pp. (Reprinted from the _Nautical │ Magazine_ for March, 1853.) =1853= │ =R= =S= │ „ Shipwrecks by Lightning. Copies of (90) │ papers relative to Shipwrecks by │ Lightning as prepared by Sir Snow Harris, │ and presented by him to the Admiralty. │ Fol. 82 pp. 5 plates. _London_, =1854= │ ¤S¤│=Harris=, W. S. On the relative cost and │ efficiency of Lightning Conductors. 8vo. =1859= │ =R= ¤A¤ │ „ A treatise on Frictional Electricity. │ (Edited by C. Tomlinson.) 8vo. _London_, =1867= │ ¤S¤│=Harting=, P. Notice sur un cas de │ formation de fulgurites et sur la │ présence d’autres fulgurites dans le sol _Amsterdam_, │ de la Néerlande 4to. =1874= │ ¤R¤ │=Hartmann=, J. F. Verbesserter Versuch │ seines künstl. elektr. Blitzes. 8vo. │ (_Hamb. Mag._ xxiv. 1759.) _Hamburg_, =1759= │ ¤A¤ │ „ Gedanken über den Ursprunz der │ Luftelektricität bei Gewittern. =1763= │ ¤R¤ │ „ Newen Erklarung der Entstehungsart der │ Donnerwetter. (_Göttingischen gemein, _Göttingen_, │ Abhandl. von J._ 1775.) =1775= │ ¤R¤ =S= │=Harward=, S. A Discourse of the several │ Kinds and Causes of Lightnings, written │ by occasion of a fearefull Lightning │ which, on the 17th day of Nouember, Anno │ Dom. 1606, did in a very short time, │ burne vp the spire steeple of │ Bletchingley, in Surrey, and in the same │ melt into fragments a Goodly Ring of │ Bells. 4to. _London_, =1607= │ ¤R¤ │=Hassencamp=, J. M. Wie ein Ort durch │ Wetterableiter su sichern. _Rinteln_, =1782= │ ¤R¤ │ „ Von den grossen Plätzen d. │ Strahlableiter, u. ihrer │ vortheilhaftesten Einrichtung zur │ Beschützung ganzer Städte. _Rinteln_, =1784= │ ¤R¤ ¤A¤ │=Hauch=, A. W. von. Von der Luftelekt. │ besonders mit Anwendung auf _Kopenhagen_, │ Gewitterableiter. 8vo. =1800= │ =R= ¤A¤ │=Hehl.= Anleitung zur Errichtung und │ Untersuchung der Blitzableiter fur │ Bauverständige, Bau- und Feuerbeschauer _Stuttgart_, │ und Gebäude-Inhaber. 8vo. 54 pp. =1827= │ ¤R¤ │=Heinrich=, P. Ueber die Wirkung des │ Geschützes auf Gewitterwolken. 4to. │ (_Neue Abhandl. der Baierischen Akad. │ Philos._ v. p. i.) _München_, =1789= │ ¤A¤ │=Helfenzreider=, J. E. Verbesserung der _Eichstadt_, │ Blitzableiter. 8vo. =1783= │ =R= │ „ Vorschlag ... die Blitzableiter zu _Salzburg_, │ verbessern. 8vo. 15 pp. =1785= │ ¤R¤ │ „ A new invention in Lightning │ Conductors. 8vo. (_Abhand. eine │ Privat-Gesellschaft_, vol. i. No. 12.) _München_, =1792= │ ¤R¤ │ „ Handgriffe bey Errichtung eines │ Blitzableiters von verbesserter Art. 8vo. │ (_Abhand. einer Privat-Ges. in │ Ober-Deutschland_, Th. i. p. 193.) _München_, =1792= │ ¤R¤ │=Helmuth=, J. H. Von d. wohlthätig. │ Erfindung d. Blitzableiters. (_Braunschw. │ Anzeig_, 17 7, S. 55.) =1777= │ =R= │=Helvig=, C. G. Bemerkungen über Blitz und │ Donner, nebst Vermuthungen über das │ Entstehen der Luft-Erscheinungen. 8vo. 32 │ pp. 1 plate. (_Gilbert’s Ann. d. Physik_, │ li. S. 2, S. 10.) _Leipsig_, =1815= │ ¤R¤ │=Hemmer=, J. J. Beschreibung einiger │ merkwürdiger Wetterschläge. 4to. │ (_Commentat. Acad. Theodoro-Palatinæ_ iv. _Mannheim_, │ _Phys._ p. 87.) =1780= │ ¤R¤ │ „ Zergliederung des beständigen │ Elektrizitäts-Trägers. 4to. (_Commentat. │ Acad. Theodoro-Palatinæ_ iv. _Phys._ p. _Mannheim_, │ 94.) =1780= │ ¤R¤ │ „ Kurzer Begriff u. Nutzen d. _Düsseldorf_, │ Wetterableiter, u. s. w. 8vo. =1782= │ ¤A¤ │ „ Kurzer Begriff und Nutzen der _Mannheim_, │ Blitzableiter. 8vo. =1783= │ ¤R¤ ¤A¤ │ „ Kurze und deutliche Anweisung wie man, │ durch einen in jedem Orte wohnenden │ Schmied, oder andere in Metall arbeitende │ Handwerker, eine sichere Wetterableitung │ mit sehr geringen Kosten in allerhand _Friedrichstadt_, │ Gebäuden anlegen lassen kann. 8vo. =1783= │ │=Hemmer=, J. J. De fulminis ictibus in │ campanas, quæ pulsantur, ubi electricitas │ nubium ac fulminis theoria, nova et │ uberiore luce perfunduntur. 4to. │ (_Commentat. Acad. Theodoro-Palatinæ_ v. _Mannheim_, │ _Phys._ p. 237.) =1784= │ │ „ Über d. Glockenläuten bey Gewittern. │ 4to. (_Commentat. Acad. _Mannheim_, │ Theodoro-Palatinæ_ v. 1784.) =1784= │ ¤A¤ ¤S¤│ „ Anleitung Wasserableiter an allen │ Gattungen von Gebäuden auf die sicherste _Frankfurt_, │ Art anzulegen. 8vo. =1786= │ ¤R¤ │ „ Anleitung Wetterableiter ... _Offenbach_, │ anzulegen. 8vo. =1786= │ =R= │ „ Anleitung Wetterleiter ... anzulegen. _Mannheim_, │ 2nd edition. 8vo. 232 pp. =1788= │ ¤R¤ =S= │ „ Verhaltungsregeln wenn man sich zur │ gewitterzeit in keinem bewaffneten _Mannheim_, │ gebäude befindet. =1789= │ ¤R¤ │ „ Unterr. z. sicherst Anleg. d. _Mannheim_, │ Wetterableiter. 8vo. =1808= │ ¤R¤ ¤A¤ │ „ Rathgeber wie man sich vor Gewittern │ in unbewaffneten Gebäuden verwahren soll. _Mannheim_, │ 8vo. 1 plate. =1809= │ ¤R¤ │ „ Conductorum fulmineorum vim egregiam │ tribus recentioribus exemplis docet. 4to. │ (_Commentat. Acad. Theodoro-Palatinæ_ vi. _Mannheim_, │ _Phys._ 516.) =1790= │ =R= ¤S¤ │ „ Nachricht von den in Kurpfalz │ angelegtern Wetterleiten. 4to. │ (_Commentat. Acad. Theodoro-Palatinæ_ iv. │ _Phys._ p. 21.) _Mannheim_ │ ¤R¤ │ „ Enarrationes conductorum fulminis │ superiore quinquennio variis in locis a │ se positorum. 4to. (_Commentat. Acad. _Mannheim_, │ Theodoro-Palatinæ_ v. _Phys._ p. 295.) =1784= │ =R= ¤S¤ │=Henley=, W. An account of the death of a │ person destroyed by Lightning in the │ Chapel in Tottenham Court Road, and its │ effects on the building; as observed by │ Mr. Wm. Henley, Mr. Edward Nairne, and │ Mr. Wm. Jones. 4to. 8 pp. 1 plate. │ (_Phil. Trans._ lxii. 133.) _London_, =1773= │ ¤R¤ ¤C¤ │ „ Experiments concerning the different ¤A¤ ¤S¤ │ efficacy of pointed and blunted rods in │ securing buildings against the stroke of │ Lightning. 4to. (_Phil. Trans._, 1774, p. │ 133.) _London_, =1774= │ ¤R¤ ¤A¤ │=Henry=, J. Method of protecting from │ Lightning buildings covered with metallic │ roofs. 8vo. (_Proc. of Amer. Phil. Soc._ │ iv. 179.) =1845= │ =R= │ „ Report concerning a letter of S. D. │ Ingram to R. Patterson relative to the │ effect of Thunder on Telegraphic wires. │ 8vo. 9 pp. =1846= │ =S= │ „ Directions for constructing Lightning _Washington_, (99) │ Rods. 8vo. =1871= │ =C= │ „ Instructions for observations of │ thunderstorms. 1 p. (Smithsonian │ Institution.) │ =S=│=Hepburn=, J. S. Should Lightning │ Conductors terminate in a point or in a │ ball? (_Proc. Roy. Scot. Soc. Arts._) _Edinburgh_, │ 8vo. =1855= │ ¤S¤│=Hericard de Thury.= De l’influence des │ arbres sur la foudre et ses effets. 8vo. =1838= │ ¤R¤ │=Herlicius=, D. (Herlich, &c.) Tractatus de │ fulmine et aliis impressionibus, │ prodigiis et miraculis. Vom Blitz, Donner │ und allerlei Feurzeichen, u.s.w. 4to. _Starg_, =1604= │ ¤C¤ ¤S¤│=Hervieu=, ——. Essai sur l’éléctricité │ Atmosphèrique. 8vo. =1835= │ ¤R¤ ¤S¤ │=Highton=, E. Effects of Atmospheric │ Electricity. 8vo. =1847= │ │=Hilliard=, J. Account of Fire from Heaven │ burning the body of J. Hitchell, of │ Christchurch, and fearfully burning the │ town of Dorchester. 4to. _London_, =1613= │ ¤A¤ │=Holtz=, W. Uber die Theorie, die Anlage, _Griefswald_, │ und die Prüfung der Blitzableiter. 8vo. =1878= │ =C= │=Hooke=, R. The Posthumous works of, │ containing his Cutlerian Lectures, and │ other discoveries. Published by Richard │ Waller, R.S. Sec. Fol. 572 pp. 1 plate. _London_, =1705= │ =R= │=Hoppe=, M. Über das Gewitter. 4to. 18 pp. │ (_Program des Fürstlich. Hedwigschen │ Gymnasium, in Neustettin ... 10 und 11 _Neustettin_, │ April_ 1865.) =1865= │ ¤R¤ │=Horner=, J. K. Bemerkung über │ Blitzableiter u.s.w. _Zürich_, =1816= │ (99) =S=│=Hugueny=, F. Le coup de foudre de l’ile du _Strasbourg_, │ Rhin. 4to. =1869= │ │ =R= ¤A¤ │=Imhof=, M. Über das Schiessen gegen │ heranziehende Donner- und Hagel-Gewitter. │ (_Read 28th March, 1811._) 4to. 24 pp. _München_, =1811= │ ¤R¤ ¤A¤ │ „ Theoretisch prakt. Anweisung zur │ Anlegung der Blitzableitern. 8vo. _München_, =1816= │ │ =S=│=James=, J. O. N. Memorandum on the │ Thunderstorm which passed over Calcutta │ 8th June, 1871 (_Proc. Asiatic Soc. _Calcutta_, │ Bengal._) 8vo. =1871= │ (111) =S=│=Jarriant.= Nouveau Paratonnerre accepté │ par l’Académie des Sciences. 8vo. _Paris_, =1877= │ (115) =S=│ „ Etude sur les Paratonnerres. 8vo. _Paris_, =1878= │ (117) =S=│=Johnston=, W. P. Report on the Lightning _Calcutta_, │ Conductors at Dum Dum, Calcutta. 4to. =1878= │ │=Jungnitz=, L. A. Über d. Erfolg. d. │ Blitzfeuer auf d. Schneekoppe. 8vo. _Breslau_, =1805= │ ¤R¤ │ „ Darstell, d. Erfolgs d. auf d. │ Schneekoppe v. H. v. Lindener 1805 │ angestellten u. an mehreren Orten │ beobachteten Blitzfeuer. 8vo. _Breslau_, =1806= │ │ (114) =S=│=Karsten=, G. Ueber Blitzableiter und │ Blitzschläge in Gebäude welche mit │ Blitzableitern versehen waren. 8vo. _Kiel_, =1877= │ =S=│ „ Gemeinfatzliche Bemerkungen ueber die │ Elektricität des Gewitters und die │ Wirkung der Blitzableiter. 1st edition. │ 8vo. _Kiel_, =1879= │ (119) =S=│ „ 2nd Edition. 8vo. _Kiel_, =1879= │ =S=│ „ 3rd Edition. 8vo. _Kiel_, =1880= │ ¤R¤ │=Kirchhoff=, N. A. J. Zurüstung, die │ Wirkung der Gewitterwolken darzustellen. │ 8vo. (_Gött. Mag._ J. i. 1780, St. ii. _Göttingen_, │ pp. 322–26). =1780= │ ¤R¤ │ „ Beschreibung einer Zurüstung, welche │ die anziehende Kraft der Erde gegen die │ Gewitterwolke, &c.... beweiset ... nebst _Berlin, Nicolai, │ e. Beschreib. versch.... Maschin. 8vo. 56 and Hamburg_, │ pp. 1 plate. =1781= │ ¤R¤ │=Kirchmaier=, G. C. De fulmine et tonitru. _Viteberg_, │ =1659= │ ¤R¤ ¤S¤ │=Kirchvogl=, A. B. De natura electr. aereæ. │ 8vo. =1767= │ =C= ¤S¤│=Klasen=, L. Die Blitzableiter in ihrer │ Construction und Anlage. 8vo. 74 pp. _Leipzig_, =1879= │ ¤A¤ │=Klein=, H. J. Das Gewitter und die │ dasselbe begleitenden Erscheinungen. 8vo. _Gratz_, =1871= │ =R= │=Klugel=, G. S. Beschreib. d. Wirkung, ein. │ heftig. Gewitters d. 12 Juli 1789 zu │ Halle, nebst Erklärung d. Entstehung d. │ Gewitters. 8vo. 64 pp. _Halle_, =1789= │ =S=│=Koenig=, J. G. De Fulmine, Fulgure, ac │ Tonitru Hiemali. 4to. _Norica_, =1706= │ =S=│=Krayenhoff=, Baron. Handleiding tot het _Nijmegen_, │ stellen van Bliksemafleiders. 8vo. =1836= │ ¤A¤ │=Krull=, J. G. Versuche zur Bestätigung der │ Meinung, dass die elektrische Materie mit │ der Materie des Donners und Blitzes eine _Hannover_, │ gross Aehnlichkeit habe. =1752= │ ¤R¤ │=Kuhn=, K. G. Ueber Blitzableiter. “In d. │ Gelehrt Anzeigen d. Königl. bayer Acad. │ von. 1851 u. 1852;” _or_ in “Astronom │ Kalender 1850–52.” =1851–2= │ _Note._—It seems uncertain to which │ this entry belongs. │ ¤A¤ │=Kuhn=, K. G. Handbuch der angewandten │ Elektricitätslehre. Part I. Ueber │ Blitzableiter. 8vo. _Leipzig_, =1866= │ =S=│ „ Bemerkungen ueber Blitzschläge. 8vo. _Munchen_, =1867= │ ¤S¤│ „ üb. d. Anordnung v. Blitzableitern, f. │ Pulvermagazine. _Münch._, =1867= │ ¤R¤ │=Kyper= (Kieper), A. Disp. de fulmine quod │ a. 1636 ... turrim nitrariam aulicam │ Regiomonti percussit. =1637= │ │ ¤A¤ │=Lampadius=, W. A. Ueber die Electricität │ der Atmosphäre. _Berlin_, =1793= │ ¤A¤ │ „ Versuche und Beobachtungen über │ Elektricität und Wärme der Atmosphäre. │ 8vo. _Leipzig_, =1805= │ ¤A¤ │ „ Ein Schneegewitter und ein Vorschlag │ zur Vervollkommung der Blitzableiter. │ (_Gilberts Ann. der Physik_, xxix. 58.) =1805= │ ¤R¤ │=Lamy=, F. Conjectures physiques sur deux │ colomnes (sic) de Nuë qui ont parus │ depuis quelques années; et sur les plus │ extraordinaires effets du Tonnerre; avec │ une explication de ce qui s’est dit │ jusqu’icy des Trombes de mer; et une │ nouvelle addition, ou l’on verra de │ quelle manière le Tonnerre tombé │ nouvellement sur une Eglise de Lagni a │ imprimé sur une nappe d’autel une partie │ considérable du Canon de la Messe. 12mo. │ 241 pp. 3 plates. _Paris_, =1689= │ │ „ A German account of the extraordinary │ effects of Lightning at the Church of │ Lagni, printed in the _Hamburg Mag._ iii. │ 226, and taken from Lamy’s French work, │ “Conjectures Phys.”, ... dated 1696, │ 12mo. is given in Bauer, Abhandl. 1770, │ p. 161. │ _Note._—This German account contains a │ copy of “la partie considérable du │ Canon de la Messe,” which was found │ printed by lightning upon the │ altar-cloth, and also of certain │ parts in red ink not thus reprinted. │ (134) =S=│=Lacoine=, E. Establissement de la formule │ relative au rayon d’Action des │ paratonnerres (_L’Electricité_, October, │ 1880.) _Paris_, =1880= │ =R= │=Landriani=, M. Gli effetti del Fulmine │ caduto la sera del 25 Agosto, 1780, nel │ campanile e Monastero di S. Vincenzo al │ Castello in Milano. 4to. 6 pp. (_Opus. │ Scelti_, iii. 328.) _Milano_, =1780= │ =R= │ „ Dell’ utilità dei Conduttori │ elettrici. 8vo. 304 pp.1 plate. _Milano_, =1784= │ │ „ Abhandlung vom Nutzen der │ Blitzableiter. Auf Befehl der Guberniss │ herausgegeben. Aus dem Italiänischen von │ G. Muller. 8vo. _Wien_, =1786= │ =R= │ „ Altra ricaduta del propagatore ... │ ossia ultima risposta contro la difesa │ dei Paragrandini. Lettera all’ Ateneo di │ Venezia. 8vo. 60 pp. _Milano_, =1826= │ ¤R¤ │=Langenbucher=, J. Richtige Begriffe vom _Augsburg_, │ Blitz und von Blitzableitern. 8vo. =1783= │ =S=│=Langlois=, E. H. Notice sur l’incendie de │ la Cathédrale de Rouen occasionné par la │ foudre, le 15 Septembre, 1822. 8vo. _Rouen_, =1823= │ (This Cathedral is reported to have │ been struck by Lightning in 1110, │ 1117, 1284, 1351, 1625, 1627, 1642, │ 1768 and 1822.) │ ¤R¤ │=Lanteires=, J. Essai sur le Tonnerre │ considéré dans ses effets moraux sur les │ hommes, et sur un coup de foudre │ remarquable; suivis des notes │ communiquées à l’auteur par M. le _Lausanne_, │ Professeur Saussure, à Genève. 8vo. =1789= │ │=La Place.= (_See Official Instructions, │ France._) │ =R= ¤A¤ │=Lapostolle.= Traité des Parafoudres et des =S= │ Paragrêles en cordes de paille. 8vo. 320 │ pp. &c., also 3 supplements. _Amiens_, =1820= │ =R= │ „ Trattato sul modo di preservare le │ abitazioni dal Fulmine e le campagne │ dalla Grandine. Opera volgarizzata da │ Bodei. 8vo. 189 pp. 1 table. _Milano_, =1821= │ =C= │ „ Ueber Blitz-und hagelableiter an _Wiln. u. Prag_, │ Stroh-Seilen. 8vo. 54 pp. =1825= │ ¤S¤│=La Pylaie=, De. Effets extraordinaires de │ la foudre. 8vo. =1849= │ =R= =S= │=La Rive=, De. Traité de l’Electricité. 3 _Paris_, │ vols. 8vo. =1854–58= │ =R= ¤S¤ │ „ Treatise on Electricity (translated by _London_, │ Walker.) 3 vols. 8vo. =1853–58= │ =R= │=Laroque.= Note sur des Eclairs de forme │ inusitée, observés à Toulouse pendant │ l’orage du 16 Juillet, 1850. 8vo. 3 pp. _Toulouse_, │ (_Toulouse Acad._ 3e Série, vi. 349.) =1850= │ =R= │=Lathrop=, Dr. J. Fatal effects of │ Lightning. In a letter to ... Joseph │ Willard. 4to. 7 pp. (_Mem. Amer. Acad._ _Charlestown_, │ Old Series, ii. pt. ii. p. 85.) =1804= │ =R= │ „ An account of the effects of Lightning │ on the house of Jn. Mason, in Boston, in │ a letter to Joseph Willard. 4to. 4 pp. │ (_Mem. Amer. Acad._, Old Series, ii. pt. _Charlestown_, │ ii. p. 91.) =1804= │ =R= │ „ Effects of Lightning on several │ persons in the house of Samuel Cary, of │ Chelsea, August 2, 1799, in a letter to │ John Davis. 4to. 4 pp. (_Mem. Amer. _Cambridge, │ Acad._ Old Series, iii. pt. i. p. 82.) U.S._, =1809= │ =R= │ „ Effects of Lightning on the house of │ Capt. D. Merry, and several other houses │ in the vicinity, on the evening of the │ 11th May, 1805, in a letter to John │ Davis. 4to. 6 pp. (_Mem. Amer. Acad._ Old _Cambridge, │ Series, iii. pt. i. p. 86.) U.S._, =1809= │ =S=│=Laue=, J. G. De telo fulmineo. 4to. _Lipsiæ_, =1706= │ =R= │=Lee=, A. An Account of the effect of │ Lightning on Two Houses in the city of │ Philadelphia, in a letter from A. Lee to │ James Bowdoin (dated July 29, 1781). 4to. │ 6 pp. (_Mem. Amer. Acad._ Old Series, i. _Boston, U.S._, │ 247, part ii.) =1785= │ ¤R¤ │=Lehaitre.= Une instruction théor. et prat. │ sur les Paragrêles. _Bourg_, =1825= │ =C= =S=│=Leigh=, J. Directions for ensuring │ personal safety during storms, and for │ the right application of Lightning │ Conductors. 6th Edition. 12mo. _London_, =1835?= │ =R= ¤S¤ │=Leithead=, W. Electricity, its nature, │ operation, and importance. 12mo. _London_, =1837= │ ¤R¤ │=Le Normand=, L. S. Sull’ utilità dei │ Parafulmini e Paragrandini per │ l’agricoltura. Seconda edizione. 8vo. 19 │ pp. _Milano_, =1823= │ ¤A¤ │=Lenz.= Sur Combien de pieds carrés de la │ surface de la toiture doiton, en │ construisant un Paratonnerre, établir un │ Conducteur à terre? _Bullet. de la Classe │ phisico-mathématique de l’Acad. Impériale │ de St. Pétersbourg_, xv. 63. =1856= │ =R= │=Le Roy=, J. B. Lettera al Rozier su i │ Parafulmini. 4to. 2 pp. (_Scelta │ d’Opuscoli_, Nuova ed. ii. 222. │ _Translated by Fromond. It was printed in │ the_ 12_th in ed._ 1776, vol. xviii. _The │ original French version in the Journ. de │ Phys._, vol. ii.) _Milano_, =1782= │ (_See Official Instructions, France._) │ ¤R¤ │=Leschevin.= Memoir upon a process employed │ in the ci-devant Maçonnais of France, to │ avert showers of Hail and to dissipate │ Storms. By M. Leschevin, Chief Commissary │ for Gunpowder and Saltpetre at Dijon. │ (_From Millin’s Magazin Encyclopédique │ for_ 1806, tom. ii. p. 5). 8vo. 7 pp. │ (_In Phil. Mag._ xxvi. 212.) _London_, =1807= │ ¤R¤ │=Leslie=, Sir J. On the Inefficacy of │ Lightning Conductors. (_From Arella, who │ says that this statement appears in │ Fernsac, Scienze fisiche matemat._ 1829, │ p. 130.) =1829= │ ¤R¤ │=Lezay-Marnézia=, C. F. A., Marquis de. Sur │ les paratonnerres et les paragrêles. │ (_Vide_ Clerc.) │ ¤S¤│=Lichtenberg=, G. C. Verhaltungsregeln bey _Göttingen_, │ nahen Donnerwettern. =1778= │ =R= │ „ Über Gewitterfurcht und _Göttingen_, │ Blitzableitung. 8vo. =1802= │ =R= ¤A¤ │ „ Neueste Geschichte der Blitzableiter. _Göttingen_, │ 8vo. =1803= │ =R= ¤A¤ │=Lichtenberg=, G. C. Vorschlag den Donner │ auf Noten zu se tzen 8vo. (_Lichtenberg’s │ Mathem. und Phys. Schriften, &c._, i. │ 478.) │ =R= ¤A¤ │ „ Versuche zur Bestimmung der │ zweckmässigsten Form der Gewitterstangen. _Göttingen_, │ 8vo. =1803= │ =R= ¤A¤ │=Litchtenberg=, L. C. Verhaltungsmaass │ regeln bey nahen Donnerwetter nebst d. │ Mitteln sich gegen d. schädl Wirkungen d. │ Blitzes in Sicherheit zu setzen. 1 Aufl. │ 8vo. 1 plate. _Gotha_, =1774= │ ¤R¤ │ „ Verhaltungsregel bey nahen │ Donnerwetter; nebst d. Mitteln, sich │ gegen d. schädl. Wirkungen d. Blitzes in │ Sicherheit zu setzen. 2e Aufl. 1775. 8vo. │ 78 pp. 1 plate. _Gotha_, =1775= │ ¤R¤ │=Limmer=, C. P. De Tonitru. │ ¤A¤ ¤S¤│=Lining=, Dr. Letter concerning his │ experiments of electricity with a kite. │ 4to. _London_, =1754= │ =R= │=Linnæa=, E. C. Vom Blitzen der │ indianischen Kresse. 8vo. 3 pp. (Signed _Hamburg and │ by C. Linnæus.) Leipzig_, =1762= │ =R= │=Litta=, A. A. Riflessioni sulla capacità │ de’ Conduttori elettrici esposte in una │ lettera al Volta. 4to. 3 pp. (_Opus. │ Scelti_, i. 340.) _Milano_, =1778= │ ¤R¤ ¤S¤ │=Lohmeier=, P. De fulmine. 4to. _Rint_, =1676= │ ¤A¤ │=Loomis=, E. On the proper height of │ Lightning Rods. (_Sillimans’ Journ._ (2), │ x. 320.) =1851= │ =R= │=Lorgna=, A. M. Sopra una Fulminazione di │ terra. Lettera al Volta. (Verona, 15 Mag. │ 1781.) 4to. 7 pp. (_Opus. Scelti_, iv. │ 235.) _Milano_, =1781= │ │ „ Lettera (al Toaldo) sui Parafulmini. │ Verona, 14 Mag. 1778. (On an insulated │ Conductor for safety and for │ observations.) 2 pp. Risposta (_to the │ above, with the notice_ “19 Mag. rec.” 2 │ pp.) (Toaldo, G.) _Padua_, =1840= │ (The above two articles are bound │ together with an Address to some │ friends (or Dedication), and signed │ Gaetano dott. Sorgata e Jacopo Prof. │ Cecconi (of 1 page). The whole forms │ a brochure, without any proper │ title-page. It is said in the │ Dedication that the two letters were │ found (in MS.) in the Biblioteca del │ Seminario.) │ ¤R¤ │=Loss=, P. De fulmine in genere cum │ auctario. (_Pogg._ i. 1500.) _Gedani_, =1636= │ =R= │=Lozeran du Fech=, L. A. Dissertation sur │ la cause et la nature du Tonnerre et des │ Eclairs. Et Lettre de l’Auteur à M. │ Sarrau, Séc. de l’Acad. viii. pp. 12mo. _Bordeaux_, │ 100 pp. (_Accad. de Bordeaux._) =1726= │ ¤R¤ │=Luc=, J. A. De. Bemerkungen über │ elektrische Bewegungen und deren Wirkung │ auf Spitzen; desgleichen über Blitz, │ Donner und die sogenannten │ Wetter-Ableiter. (_Neue Schriften der │ Gesellsch. Naturf. Freunde_, ii. 137.) │ 8vo. _Berlin._ │ ¤R¤ │=Lucan.= On conducting Lightning. (_From │ Becquerel, Hist._) │ =R= ¤A¤ │=Luz=, J. F. Unterricht vom Blitze u. v. │ Blitz u. Wetter Ableitern. 8vo. 1 plate. _Nuremberg_, │ (_From Kuhn of 1866_, p. 279.) =1783= │ ¤R¤ ¤A¤ │ „ Lehrbuch d. theor. prakt. │ Blitzableitungslehre neu bearbeitet von │ Gutle, 1te Theil. 8vo. =1804= │ ¤R¤ ¤A¤ │ „ Unterricht vom Blitz und den Blitz-und │ Wetter Ableitern ... neu bearbeitet von _Nurnberg_, │ Gutle. 1st Theil. 8vo. 220 pp. 1 plate. =1804= │ ¤R¤ │=Lyon=, J. Account of several new and │ interesting phænomena discovered in │ examining the bodies of a man and four │ horses killed by Lightning near Dover. │ 8vo. _London_, =1796= │ │ =R= ¤A¤ │=Macfait=, E. Observations on Thunder and │ Electricity (_Essays and Obs. Phys. and _Edinburgh_, │ Lit._ Vol. 1, p. 189. 8vo.) =1754= │ =C= =S= │=McGregor=, W. Protection of Life and (106) │ Property from Lightning. 8vo. _Bedford_, =1875= │ ¤A¤ │=Maffei=, F S. Delle formazione dei │ Fulmini. 4to. _Verona_, =1747= │ ¤R¤ │=Maffioli= di Udine. On Lightning │ Conductors. (_Giornale d’Italia_, 25 │ Agosto, 1770.) =1770= │ ¤R¤ │=Magnin=, A. Le feu du ciel, histoire de │ l’électricité et de ses principales │ applications. Idées des anciens, │ premières observations, machine │ éléctrique, bouteille de Leide, │ paratonnerre, &c. 3e édition. 8vo. 240 │ pp. _Tours_, =1866= │ =R= │=Magrini=. L. Sopra un metodo di togliere │ alle nubi maggiore copia di elettricità │ che coll ordinario parafulmine. Nota │ letta 25 Agost, 1859. 4to. 3 pp. _Milano_, =1860= │ =R= │ „ Sulla meteora che nella sera del 4 │ Marzo, 1861, colpiva la cattedrale di │ Milano; e sulla riforma de’ suoi │ Parafulmini. Memoria. 4to. 11 p. _Milano_, =1861= │ ¤S¤│ „ Sulla elettricita atmosferica. 4to. _Milan_, =1863= │ =R= ¤S¤ │=Mahon=, Viscount. Principles of │ Electricity. 4to. =1779= │ ¤R¤ │=Mairan=, J. J. d’O. de. Sur les effets de │ la chute du Tonnerre sur un arbre. 4to. │ (_Mém. Par._ 1724.) _Paris_, =1724= │ =C= =S= │=Majendie=, V. D. Report on the destruction (74) │ by Lightning of a Gunpowder store. fcp. │ fol. (Official Report—unpublished.) _London_ │ ¤R¤ │=Majocchi=, G. A. Istruzione teorica e │ pratica sui Parafulmini. 8vo. 114 pp. 1 │ plate. _Milano_, =1826= │ =C= │=Majoli Simonis=. Hoc est colloquia physica │ noua et admiranda tum lectu incunda et │ supra fidem recreabilia tum cognitu, │ insignia et penitus necessaria. Fol. 1428 _Moguntiæ_, │ pp. and Index. =1625= │ =R= │=Mako= (von Kerek Gede), P. Dissertatio │ physica de natura, et remediis Fulminum. │ 8vo. 100 pp. _Goritiæ_, =1773= │ ¤R¤ ¤A¤ │=Mako=, P. und =Retzer=. Physikalische ¤S¤ │ Abhandlung von den Eigenschaften des │ Donners, und den Mitteln wider das │ Einschlagen. Verfaszt von P. Mako und von │ J. E. von Retzer in das Deutsche │ übersetzt. 1st ed. 8vo. 125 pp. 1 plate. _Wien_, =1772= │ ¤R¤ │ „ Physikalische Abhandlung von den │ Eigenschaften des Donners, u. d. Mitteln │ wider das Einschlagen. Verfaszt von P. │ Mako, und von J. E. Retzer, in das │ Deutsch, übersetzt. 2te Aufl. (_Von │ Retzer aus d. latein Orig. das erst._ │ 1773 _erschien_.) _Wien_, =1775= │ =C= ¤A¤ │=Mann=, R. J., M.D. The Protection of =S= │ Buildings from Lightning. (_Journal of (108) │ Society of Arts._) 8vo. _London_, =1875= │ (131)=S=│ „ Remarks on some practical points │ connected with the construction of │ Lightning Conductors. (_Quarterly Journal │ of the Meteorological Society._) 8vo. _London_, =1875= │ =R= │=Marini=, P. Relazione Memoria sul Fulmine │ caduto in Brescia nella torre della │ Paletta 1803, e Sul Parafulmine costrutto │ sopra al palazzo della Loggia da lui │ 1805. 8vo. (_Comment. dell’ Accad.... del │ Dipartimento del Mella_, tom. i. _Elenco │ delle Memorie_.) _Brescia_, =1808= │ ¤R¤ │=Marsault=, J. P. L. Electro-calorique, ou │ les Paratonnerres réformés ... où l’on │ trouve un nouveau plan de paratonnerre, │ etc. 18mo. 76 pp. _Niort_, =1852= │ =R= │=Martin.= Mémoire sur un coup de Tonnerre │ qui a éclaté dans l’Eglise de St. Nicolas │ de Toulouse ... 17 March, 1787. 4to. 9 │ pp. (_Toulouse Acad._ 1re série, iv. _Toulouse_, │ 100.) =1790= │ =C= =S=│=Martin=, T. H. La foudre, l’électricité et │ le magnétisme chez les anciens. 12mo. _Paris_, =1866= │ ¤R¤ ¤A¤ │=Marum=, M. van. Verhandeling over het _Groningen_, │ Electrizeeren. 8vo. =1776= │ ¤R¤ │ „ Sur les paratonnerres. 4to. (_Jour. │ Phys._ 1787, xxxi.) _Paris_, =1787= │ ¤R¤ │=Marzari=, G. On Conductors for Lightning. │ Account of his Admonitions, &c. (_Treviso _Padova_, │ Athenæum_, vol. ii. p. 73) (=1832?=) │ =R= │ „ (or Anon.) Maniera pratica di fare li │ conduttori ai campanili, alle chiese, ed │ alle case, descritta per uso dei fabbri, │ falegnami, e muratori, &c.... stampata │ per ordine del Magistrato Excell. Alla │ Sanità. 4to. 37 pp. _Venezia_, =1787= │ =R= │=Mawgridge=, R. A.... relation of the ... │ effects of an unusual clap of Thunder and │ Lightning. 4to. 2 pp. (_Phil. Trans._ │ xix. for 1695–6–7, p. 782.) _London_, =1698= │ =R= │=Maxwell=, H. Observations on Trees as │ Conductors of Lightning. Communication │ dated June 21, 1787. 4to. 2 pp. (_Mem. │ Amer. Acad._ old series, ii. part i. p. _Boston, U.S._, │ 143.) =1793= │ =C= =S= │=Maxwell=, Prof. J. Clerk. On the (109) │ protection of buildings from Lightning. │ 8vo. (_British Association Report_) _London_, =1877= │ ¤R¤ │=May=, W. Verhall der uitwerkinge van eenen │ enkelden blixemslag, voorgevallen op een │ van’s lands oorlogscheepen, in het jaar │ 1749. (_Verhandel. van het Maatsch. te │ Haarlem_, xii. 391.) _Haarlem_ │ ¤R¤ │=Mayr=, G. Abhandlung üb. Elektricität und │ sichernde Blitz-Ableiter für jedes │ Gebäude für Reise-u. Frachtwagen, │ Schiffe, Bäume u. Denkmäler. Nebst e. │ Anh. über Hagel-Ableiter. Geprüft (2 │ Aufl.) neu. u. verbess. 12mo. _München_, =1839= │ =R= │=Melandri=, G. Disquisizione sui │ Paragrandini. Letta nell’ Ateneo di │ Treviso il 15 Dec. 1825. 4to. 26 pp. │ (_Inserita nel_ vol. x. _del Gle. sulle │ Scienze ... delle provincie Venete_.) _Treviso_, =1826= │ =R= │ „ Considerazioni critiche sopra │ l’efficacia del Paragrandine metallico │ ... 8vo. 37 pp. _Firenze_, =1827= │ ¤A¤ =S= │=Melsens=, L. F. H. Notes sur les _Bruxelles_, (140) │ Paratonnerres (Nos. 1–5). 8vo. =1865–78= │ ¤A¤ =S= │ „ Notice sur le coup de foudre de la _Bruxelles_, (137) │ gare d’Anvers. 8vo. =1875= │ ¤A¤ =S=│ „ Des paratonnerres à pointes, à (138)│ conducteurs et à raccordements terrestres _Bruxelles_, │ multiples. Large 8vo. =1877= │ =S=│ „ Communication verbale. 8vo. (_See _Bruxelles_, │ Bourges_). =1877= │ ¤R¤ =C= │=Meredith.= Considerations on the utility ¤S¤ │ of Conductors ... 8vo. 1 plate. _London_, =1789= │ ¤R¤ │=Mermet=, A. C. Memoir on Lightning │ Conductors. Prize question, Bordeaux _Bordeaux_, │ Academy. 8vo. =1837= │ ¤R¤ │=Metterkamp=, D. C. Über Blitzableitungen, │ gegen Busse’s Theorie. 8vo. _Leipsig_, =1812= │ ¤R¤ ¤A¤ │=Meurer=, H. Abhandl. v. d. Blitze u. d. │ Verwahrungsmitteln dag. 4to. _Trier_, =1791= │ =R= │=Michaelis.= Briefwechsel zwischen │ Michaelis und Lichtenberg über die │ Absicht oder Folgen der Spitzen auf │ Salomon’s Tempel. 8vo. (_Gætingischer _Gættingen_, │ Mag._ 3e année.) =1783= │ _Note._—Martin says that this is also │ in G. C. Lichtenberg’s Physikalische │ und Mathem. Schriften, tom. iii. p. │ 251–301. Gœttingen, 1803, in 12mo., │ (Vermischte Schriften, 1800–1805. 9 │ vols. 12mo. _Gotha_.) │ =R= │=Michaelis= und =Lichtenburg=. Briefwechsel │ über die Absicht oder Folgen der Spitzen │ auf Salomon’s Tempel, 1783. 8vo. │ (_Lichtenberg’s Math. und Phys. │ Schriften_ iii. 251, _and in Gött. Mag._ _Göttingen_, │ i. iii., (1873), St. v.p. 735–68.) =1804= │ │=Michel=, F. (_See Official Instructions, │ France_). │ =S=│=Mittelstrass.= Die Blitzableiter nach den │ neuesten Erfahrungen zweckmässigster _Magdeburg_, │ Construction. 8vo. =1871= │ (106) =S=│=Mohn=, H. Lynildens farlighed i Norge. _Kristiania_, │ 4to. =1875= │ =S=│=Monnet=, P. A. Nouveau procédé pour │ étudier l’électricité atmosphérique. 8vo. _Lyon_, =1865= │ ¤R¤ │=Mountaine=, W. An account of some │ extraordinary effects of Lightning, July │ 16, 1759, with some remarks by Gowin │ Knight. 4to. (_Phil. Trans._ an. 1759, p. │ 294.) _London_, =1759= │ ¤R¤ │=Muller=, C. H. Über Lapostolle’s │ Blitzableiter. 8vo. (_Gilb. Ann._ lxviii. │ 1821.) _Leipzig_, =1821= │ =R= │=Murray=, J. On a singular effect produced │ by Lightning. 8vo. 2 pp. (_Phil. Mag._ │ lx. 61.) _London_, =1822= │ =C= =S=│ „ A Treatise on Atmospherical (82)│ Electricity. 8vo. _London_, =1830= │ =R= =S= │ „ The Description of a new Lightning │ Conductor. 8vo. 1 plate. 63 pp. _London_, =1833= │ =R= ¤A¤ │ „ Lightning Conductors. 8vo. 2 pp. │ (_Annals of Electricity_, vii. 82.) _London_, =1841= │ =C= │=Murray=, J. Electricité atmospherique │ comprenant les instructions nécessaire │ pour établir les paratonnerres et les │ paragrêles. Traduit de l’Anglais. Sm. │ 8vo. 264 pp. _Paris_, =1877= │ ¤A¤ │=Murray=, N. Treatise on Atmospheric │ Electricity, including observations on │ Lightning Rods. 8vo. _London_, =1828= │ ¤R¤ ¤A¤ │=Mylius=, C. Nachrichten und Gedanken von │ der Elektricität des Donners. 8vo. _Berlin_, =1752= │ │ =R= ¤A¤ │=Nairne=, E. Experiments on Electricity, │ being an attempt to show the advantage of │ elevated pointed Conductors. Read at the │ Royal Society, June 18th and 25th, 1778. │ 4to. 40 pp. 4 plates. (_Phil. Trans._ │ 1778, p. 823.) _London_, =1779= │ ¤R¤ │ „ An account of the effect of │ Electricity in shortening Wires. 4to. │ (_Phil. Trans._ 1780, p. 334.) _London_, =1780= │ ¤R¤ │ „ Letter—containing an account of Wire │ being shortened by Lightning. 4to. │ (_Phil. Trans._ 1783, p. 223.) _London_, =1783= │ ¤R¤ │=Nauwerck=, C. L. Versuche neuer Erklärung │ u. Folge der jetzigen Witterung auf │ Oekonomie anwendbar, mit meteorolog. │ Bemerkk. die Gewitterableiter betreffend. _Dresden u. │ 8vo. Leipzig_, =1787= │ ¤R¤ │=Needham=, J. T. Recherches sur la question │ si le son des cloches pendant les orages │ fait éclater la foudre en la faisant │ descendre sur le clocher, etc. (_Mém. de _Bruxelles_, │ Brux._ iv., 1783.) =1783= │ ¤R¤ │=Neeff=, C. E. Beschreib. u. Anwend. d. │ Blitzrades. 8vo. (_Poggend. Ann._ xxxvi., │ 1835.) _Leipzig_, =1835= │ ¤A¤ │=Newall=, R. S. Lightning Conductors: their │ use as protectors of buildings, and how │ to apply them. 8vo. _London_, =1876= │ ¤A¤ │=Nippoldt=, Dr. Dimensions of Lightning │ Rods. (_Telegraphic Journal_, vi. 78.) =1878= │ ¤R¤ ¤A¤ │=Nollet=, J. A. Mémoire sur les effets du │ Tonnerre comparés à ceux de l’Electricité │ avec quelques considérations sur les │ moyens de se garantir des premiers. 4to. │ (_Mém. de Paris_, an. 1764, _Hist._ p. 1, │ _Mém._ p. 408.) _Paris_, =1764= │ =S=│ „ Vergleichung der Würkungen des Donners │ mit dem Würkungen der Electricität. │ (_Mêm. de Paris_, 1764.) 8vo. _Prag_, =1769= │ │ =R= │=Oliver=, A. (Salem). A Theory of Lightning │ and Thunder Storms. 4to. 28 pp. (_Trans. _Philadelphia_, │ Amer. Phil. Soc._ Old Series, ii. p. 74.) =1786= │ ¤R¤ │=Orliaguet=, M. Essai sur le paratonnerre _Limoges et │ et le paragrêle. 8vo. 19 pp. Paris_, =1865= │ ¤R¤ │=Ostertag=, J. P. Prgrm. von d. │ Blitzableitern. 4to. (_From Pogg._ ii. _Regensburg_, │ 337.) =1781= │ │ ¤R¤ │=Pasumot=, Fra. Observations sur les effets │ de la foudre dans une maison de Paris. =1784= │ =R= │=Patterson=, R. An improvement on Metallic │ Conductors, or Lightning Rods: in a │ letter to D. Rittenhouse, honoured with │ the Magallanic Premium ... Dec., 1792. │ Read Nov. 5, 1790. 4to. 4 pp. (_Trans. │ Amer. Phil. Soc._, Old Series, vol. iii. _Philadelphia_, │ 321.) =1793= │ ¤S¤│=Peck=, F. _Desiderata Curiosa_, vol. ii., │ folio (contains, “Surprizing effect of │ Lightning at Barton, Notts.”) =1735= │ ¤R¤ │=Pelison.= Blitzfanger. (_Abhandl. d. │ naturforsch. Gesells. zu Berlin_ v Jahr │ 1792, x.) │ =C= │=Peltier=, J. C. A. Recherches sur la cause │ des phénomènes électrique e l’atmosphère, │ etc. 8vo. 49 pp. (_Annales de Chimie._) _Paris_, =1842= │ =C= │ „ An enquiry into the cause of the │ Electric phenomena of the atmosphere, │ etc. 8vo. 38 pp. (_Taylor’s Scientific │ Memoirs_, vol. iii.) _London_, =1842= │ =S=│ „ Sur le trombe de Monville (clivage des │ arbres par la foudre). 4to. _Rouen_, =1845= │ ¤S¤│ „ Notice sur la Foudre. 8vo. _Paris_, =1845= │ ¤R¤ │=Perego=, A. Relazione sul Fulmine caduto │ in Iseo, il 17 Mag. 1833. (_Comment. │ Ateneo Brescia_, vol. printed in 1834 pro │ 1833.) _Brescia_, =1834= │ ¤R¤ │ „ Descrizione dei danni cagionati dalla │ caduta di un fulmine in Mompiano │ provincia di Brescia. │ =S=│=Perrin=, P. Etude sur les Eclairs. 8vo. _Paris_, =1873= │ ¤R¤ ¤A¤ │=Pfaff=, C. H. Über Blitz und │ Blitzableiter. 8vo. (_Gehler’s Phys. │ Wörterbuch neu bearb._) _Leipzig_, =1825= │ (98) =S=│=Phillips=, R. On atmospheric electricity. │ 8vo. _London_, =1863= │ =C=│=Phin=, J. Plain directions for the ¤A¤=S=│ construction and erection of Lightning _New York_, (102)│ Rods. 2nd Edition. 12mo. =1873= │ ¤S¤│=Phipson=, T. L. Familiar │ Lectures—Lightning Points. 8vo. │ ¤R¤ │=Pickel=, G. Abhandl. über Blitzableiter, │ u.s.w. (_From Poggendorff_, ii. 444.) =1821= │ ¤R¤ │=Pilatre de Rozier.= Sur la cause de la │ Foudre. (_Journ. Phys._ xvi. 1780.) _Paris_, =1780= │ ¤R¤ │=Pilkington=, J. (Bishop of Durham). The │ Burning of St. Paul’s Church in London in │ 1561, on the 4th June, by Lightning. 8vo. _London_, =1561?= │ ¤R¤ ¤A¤ │=Plieninger=, Dr. Über die Blitzableiter, =S= │ ihre Vereinfachung und die Verminderung │ ihrer Kosten. Nebst einem Anhang über │ dasVerhalten der Menschen bei Gewittern. │ Eine gemeinfassliche Belehrung für die │ Verfertiger der Blitzableiter, sowie für │ die Hausbesitzer. Im Auftrage der k. │ Centralstelle des landwirthschaftlichen │ Vereins in Württemberg. 8vo. 114 pp. 3 _Stuttgart_, │ plates. =1835= │ =C= │=Pliny=, C. The historie of the World, │ commonly called the Naturall Historie of │ C. Plinius secundus. Translated into │ English by Philemon Holland. Fol. _London_, =1634= │ ¤R¤ │=Poëy=, A. Sur les tempêtes électriques et │ la quantité de victimes que la foudre │ fait annuellement aux Etats-Unis _Versailles_, │ d’Amérique et à l’île de Cuba. 8vo. =1855= │ =S=│ „ Des caractères physiques des éclairs │ en boules. 8vo. _Paris_, =1855= │ =R= ¤C¤ │ „ Analyse des hypothèses ... Eclairs _Versailles_, ¤S¤ │ sans tonnerre. Large 8vo. =1856= │ ¤S¤│ „ Sur les nombres de personnes tuées par │ la foudre dans le Royaume de │ Grande-Bretagne, de 1852 à 1856, comparé │ aux décès par fulguration en France et │ dans d’autres parties du globe. 4to. _Paris_, =1858= │ =S=│ „ Sur les éclairs sans tonnerre observés │ à la Havanne, pendant l’anné 1859. 8vo. _Paris_, =1860= │ =R==C= │ „ Relation Historique et theorie des =S= │ images Photo-Electriques de la Foudre. │ 2nd Ed. 12mo. _Paris_, =1861= │ │=Poisson.= (_See Official Instructions, │ France._) │ ¤R¤ │=Pollini.= Sul passaggio del Fulmine che │ nel ... 6 Agosto, 1795 ... scoppiò nel │ ... Tempio di S. Andrea in Vercelli, e _Vercelli_, │ sugli effetti. 8vo. =1796= │ =R=¤C¤ │=Poncelet=, M. La Nature dans la formation ¤A¤ =S= │ du Tonnerre. 8vo. _Paris_, =1766= │ =C= │=Pontano=, J. J. Liber de meteoris. Sm. │ 8vo. 225 pp. =1545= │ ¤R¤ │=Poppe=, Joh. H. M. Gewitterbüchlein zum │ Schutz und zur Sicherheit gegen d. │ Gefahren der Gewitter, besond. auch üb. │ d. Kunst, Blitzableiter auf d. beste Art _Tubingen_, │ anzulegen. 8vo. =1830= │ ¤A¤ │=Porro.= Substitution d’un Tube de Plomb à │ la Corde métallique communément employé │ comme Conducteur pour les Parontonnerres. │ (_Compt. Rend._ xxx. 86.) =1850= │ =R= ¤A¤ │=Pouillet=, C. S. M. Eléments de Physique ¤S¤ │ expérimentale. 7th Ed. 2 vols. 8vo. _Paris_, =1856= │ (_See Official Instructions, France._) │ ¤A¤ =S= │=Preece=, W. H. On Lightning and Lightning (100) │ Conductors. (_Jour. Soc. Tel. Eng._) 8vo. _London_, =1873= │ (132) =S=│ „ On the proper form of Lightning │ Conductors. (_Brit. Ass. Rep._, 1880.) _London_, =1880= │ (135) =S=│ „ On the space protected by a Lightning │ Conductor. (_Phil. Mag._, Dec. 1880.) │ 8vo. 4 pp. 1 plate. _London_, =1880= │ =R= │=Preibsch=, C. Über Blitzstrahlableiter. 32 │ pp. 1 plate. _Leipzig_, =1825= │ ¤R¤ ¤A¤ │ „ Über Blitzstrahlableiter, deren │ Nutzbarkeit und Anlegung. 2nd Edition │ enlarged, &c. (3 B.) 8vo. 46 pp. _Leipzig_, =1830= │ =R= =S= │=Priestley=, J. History of the present │ state of Electricity. 2nd Ed. 4to. _London_, =1769= │ =R= │=Putnam=, A. Remarks on L. Baldwin’s │ proposed improvement in Lightning Rods, │ in a letter to Jed. Morse. Article dated │ January 12, 1799. 4to. 6 pp. (_Mems. │ Amer. Acad._ Old Series, ii. part ii. p. _Charlestown_, │ 99.) =1804= │ │ ¤R¤ ¤S¤ │=Quatrefages=, A. de. Action de la Foudre _Toulouse_, │ sur des êtres organisés. 8vo. =1837= │ ¤R¤ │=Quinquet.= Observations sur les │ Paratonnerres. (_Journal de la Société │ des Pharmaciens de Paris_, tom. i. p. i. │ 100.) │ │ =R= │=Racagni=, G. M. Sopra alcuni conduttori │ elettrici che sono stati percossi dal │ fulmine. Memoria. Ricevuta 13 Luglio, │ 1818. 4to. 14 pp. (_Mem. della Soc. │ Ital._ xviii. 139.) _Modena_, =1820= │ ¤R¤ │ „ Sopra, alcuni edifizii muniti di │ Parafulmini Frankliniani stati dal │ Fulmine danneggiati. Memoria. Ricevuta 10 │ Nov. 1821. 4to. 26 pp. 1 plate. (_Ital. │ Soc. Mem._ xix. p. 1.) _Modena_, =1823= │ ¤R¤ │=Raven.= Account from Carolina of the │ effects of Lightning on two of the rods │ affixed to houses for securing them │ against Lightning. │ =R= =S= │=Read=, J. A summary view of the │ spontaneous electricity of the earth and │ atmosphere. 8vo. _London_, =1793= │ =S=│=Redarès=, C. Histoire abrégée du tonnerre. │ 4to. _Avignon_,=1853= │ =R= =S= │=R(édarès)=, C. Nouveaux appareils contre │ les dangers de la foudre. 8vo. _Paris_, =1846= │ =C= │=Regii=, H. Philosophia Naturalis. Editio _Amstelodami_, │ secunda. 4to. 442 pp. =1654= │ ¤R¤ │=Reich=, F. Über d. Wirk. einiger │ Blitzschläge in Freiberger Gruben. 8vo. │ (_Pogg. Ann._ lxv. 1845.) _Leipsig_, =1845= │ =R= ¤A¤ │=Reimarus=, J. A. H. Die Ursache des │ Einschlagens vom Blitze u. dessen natürl. │ Abwend, von unseren Gebäuden, aus │ zuverlässigen Erfahrungen von │ Wetterschlägen vor Augen gelegt. 8vo. 128 _Langensalsa_, │ pp. =1769= │ │ „ Ursache v. Einschlagen des Blitzes. │ 8vo. _Leipzig_, =1774= │ =R= =S= │ „ Vorschriften zur Anlegung einer │ Blitz-Ableitung an allerley Gebäuden nach │ zuverlässigen Erfahrungen. 8vo. 24 pp. _Hamburg_, =1778= │ =R= ¤A¤ │ „ Vom Blitze: i. Dessen Bahn u. Wirk. =S= │ auf versch. Körper, &c. 8vo. 678 pp. _Hamburg_, =1778= │ =R= │ „ Nachricht von einer Zurüstung, welche │ die Wirkung der Gewitterwolke sinnlich │ darstelt. (_Deutsch. Mus._ Oct. 1779, p. │ 329. f.) =1779= │ ¤R¤ │=Reimarus=, J. A. H. Einige gegen d. │ Blitzableitung gemachte Einwürfe _Frankf.-a.-M._, │ beantwortet. 8vo. =1790= │ =R= =S= │ „ Neuere Bemerkungen vom Blitze dessen │ Bahn, Wirkung, sichern und bequemen │ Ableitung, &c. 8vo. 386 pp. 9 plates. _Hamburg_, =1794= │ ¤R¤ ¤A¤ │ „ Ausführliche Vorschriften, &c. 8vo. _Hamburg_, =1794= │ =R= │ „ Ausführliche Vorschr. z. │ Blitzableitung an allerley Gebäuden. 8vo. │ 46 pp. 2 plates. _Hamburg_, =1797= │ ¤R¤ │ „ Über Blitzschläge u. Blitzableiter. │ 8vo. (_Gilb. Ann._ vi. ix. u. xxxvi.) _Leipzig_ │ ¤A¤ │ „ Ueber die Sicherung durch │ Blitzableiter. (_Gilbert’s Ann._ xxxvi. │ 113.) =1810= │ =C= =S=│=Reinzer=, F. Meteorologia _Augustæ │ Philosophico-politica in duodecim Vindelicorum_, │ dissertationes, &c. Fol. 297 pp. =1709= │ =S=│=Reussius=, J. A. De Fulmine. 4to. _Rinthelii_, │ =1676= │ =R= =S= │=Ribbentrop=, H. G. F. Über die Blitzröhren │ oder Fulguriten und besonders über das │ Vorkommen ders. am Regensteine bei │ Blankenburg. 8vo. 46 pp. 1 plate. _Braunschweig_, │ (_Schweigger, Journ._ lvii. 1829.) =1830= │ ¤R¤ │=Richardot=, C. Nouveaux appareils contre │ le danger de la Foudre et le fléau de la │ Grêle. 8vo. 44 pp. _Paris_, =1825= │ ¤R¤ │ „ Nuovo sistema di apparecchi contro i │ pericoli de Fulmine ed il flagello della │ Grandine. Trad. dal Francese. 8vo. 45 pp. │ Indice e Lettera. _Milano_, =1827= │ =R= │=Rittenhouse= and =Hopkinson=. An account │ of the effects of a Stroke of Lightning │ on a house furnished with Two Conductors; │ in a letter ... to Mr. R. Patterson. Read │ Oct. 15, 1790. 4to. 4 pp. (_Trans. Amer. _Philadelphia_, │ Phil. Soc._ Old Series, vol. iii.) =1793= │ =R= │=Rittenhouse= and =Jones=. Account of │ several Houses in Philadelphia struck by │ lightning, June 7th, 1789. Read July 17, │ 1789. 4to. 4 pp. 1 plate. (_Trans. Amer. │ Phil. Soc._ Old Series, vol. iii. p. _Philadelphia_, │ 119.) =1793= │ ¤A¤ │=Roberts=, M. On Lightning Conductors, │ particularly as applied to vessels. 2 │ vols. 8vo. _London_, =1837= │ │=Robespierre.= Un Plaidoyer prononcé dans │ une cause relative à un Paratonnerre. │ 8vo. (_From Marget, Etude sur les travaux │ de Romas_, page 80—not the exact title.) =1783?= │ ¤A¤ │=Romas=, J. de. Neuer elektr. Versuch mit │ dem fliegenden Drachen am, 14 Nov., 1753 =1753= │ =R= ¤S¤ │ „ Mémoire sur les moyens de se garantir │ de la Foudre dans les maisons; suivi │ d’une Lettre sur l’invention du Cerf │ volant électrique, avec les pièces │ justificatives de cette même lettre. _Bordeaux_, │ 12mo. 156 pp. 2 plates. =1776= │ The Pièces Justicatives contain │ testimonials, a certificate of the │ Bordeaux Acad., &c., which prove that │ he had invented (imaginé) (but had │ not used) the Electrical Kite on the │ 12th July, 1752. Merget, Etude sur │ les travaux de Romas, imputes to │ Franklin (by implication) the │ possibility of having derived the │ idea from Romas: without foundation, │ I think.—F.R. │ =R==C= │=Ronalds=, Sir F. Catalogue of books and =S= │ papers relating to Electricity, &c. │ Compiled by Sir F. Ronalds, F.R.S., and │ published by the Society of Telegraph │ Engineers. 8vo. xxvii. 564 pp. _London_, =1880= │ ¤S¤│=Runnels=, J. Specimen inaugurale de causa │ fulminis et tonitru. 4to. _Leyde_, =1759= │ │ ¤R¤ │=Sage=, B. G. Observations sur les │ Paratonnerres. 8vo. _Paris_, =1808= │ =R= │ „ Recueil historique d’Effets │ Fulminaires. 8vo. 21 pp. _Paris_, =1822= │ │=St. Lazare.= (_See Bartholon de St. │ Lazare._) │ ¤R¤ ¤A¤ │=Saussure=, H. B. de. Manifeste, ou │ exposition abregée, de l’Utilité des │ Conducteurs électriques. 8vo. _Genève_, =1771= │ =R= │=Scaramelli=, Il Paragrandinatore istruito │ sull’ arte e sugli usi dei paragrandini e │ parafulmini alla Tholard. 8vo. 20 pp. 2 │ plates. _Venezia_, =1824= │ =R= =S= │=Schaffrath=, L. De electricitate coelesti. │ 4to. _Pestini_, =1778= │ ¤R¤ │=Scheibel=, G. E. D. d. Blitz in │ Pulverthurm verunglückte Breslau. 4to. │ (_From Heinsius._) _Breslau_, =1750= │ ¤R¤ │=Scheibel=, J. E. Einige Progr. üb. den a. │ d. Elisabetkirche zu Breslau erricht. │ Blitzableiter. =1793–4= │ =R= =S= │=Schieck=, Dr. Ueber atmosphärische _Oldenburg_, │ Electricität. 8vo. =1870= │ =C= │=Schönbein=, C. F. On some secondary │ physiological effects produced by │ Atmospheric Electricity. 8vo. _London_, =1851= │ =C= │=Schwartz=, F. Wolken und Wind, Blitz und │ Donner. 8vo. 307 pp. _Berlin_, =1879= │ ¤R¤ │=Scoresby=, Dr. W. On the singular effects │ of Two Strokes of Lightning upon a │ Vessel. 8vo. (_Brewster’s Journal of │ Science_, viii. 1828.) =1828= │ ¤R¤ │=Scudery=, D. J. Fernglas d. Artzney │ wissenschaft. nebst Abhdl. Schiffe und │ Häuser v. d. Blitz zu verwahren a. d. _Münster_, =1774= │ Italianen. 8vo. _or_ =1775= │ ¤S¤│=Secchi=, A. Di alcuni fenomeni accadute │ nella scarica di un fulmine in Alatri. │ 4to. _Rome_, =1872= │ =R= =S= │=Sestier=, F. et =Méhu=, C. De la Foudre, │ de ses formes et de ses effets sur │ l’homme, les animaux, les végétaux et les │ corps bruts; des moyens de s’en │ préserver, et des paratonnerres par F. │ Sestier. Rédigé sur les documents laissés │ ... et complété par C. Méhu. 2 vols. 8vo. _Paris_, =1866= │ =R= ¤S¤ │=Sidney=, E. Electricity, its phenomena and │ results. 16mo. _London_, =1843= │ =R= ¤A¤ │=Sigaud de la Fond=, M. Précis historique │ et expérimental des Phénomènes │ électriques. 2nd ed. 8vo. _Paris_, =1785= │ ¤R¤ =C= │=Simmons=, J. An essay on the cause of =S= │ lightning. 8vo. _Rochester_, (81) │ =1775= │ =R= │=Spallanzani=, L. Lettera al Barletti ... │ sopra un fulmine ascendente. 4to. 5 pp. │ (_Opusc. Scelti._ xiv. 296.) _Milano_, =1791= │ =C=¤A¤ │=Spang=, H. W. A Practical Treatise on =S= │ Lightning Protection. 8vo. _Philadelphia_, (112) │ =1877= │ ¤A¤ │=Sprague=, J. F. Electricity: its Theory, │ Sources and Applications. 8vo. _London_, =1875= │ ¤R¤ │=Sternberg=, Joachim Graf von. │ Beobachtungen über die Bildung der │ Donner-Wolken und Entstehung der │ Donner-Wetter. (_Mayer’s Samml. Phys. │ Aufs. des Böhmischen Naturf._ iii. p. 1.) _Prag_, =1792= │ ¤R¤ │=Stoikowich=, A. Schutzmittel wider d. _Petersburg?_ │ Blitz. =1810= │ ¤R¤ │ „ Über Blitzableiter. _Petersburg?_ │ =1826= │ ¤R¤ │=Stoll=, J. J. Beleuchtung einiger │ Vorurtheile in Ansehung der Donnerwetter │ und Blitzableiter. 8vo. _Lindau_, =1790= │ (130) │=Stotherd=, Col. Earth connections of │ Lightning Conductors. 8vo. _London_, =1875= │ ¤A¤ │=Stricker.= Ueber Anwendung des Galvanismus │ zur Prüfung der Blitzableiter. (_Pogg. │ Ann._, lxix. 554. _Polyt. Journ._ ciii. │ 265.) =1846= │ ¤A¤ ¤S¤│=Stricker=, W. Der Blitz und seine │ Wirkungen. 8vo. _Berlin_, =1872= │ =R= ¤S¤ │=Sturgeon.= Annals of Electricity. 10 vols. │ 8vo. =1836= │ =R= ¤S¤ │ „ Recent Experimental researches on │ Electricity. 8vo. _London_, =1830= │ ¤A¤ │=Sturgeon=, W. On Lightning and Lightning │ Conductors. (_Mem. of the Manch. Soc._ _Manchester_, │ (2), ix. 56.) =1851= │ │ ¤R¤ ¤A¤ │=Tavernier=, A. de. Blitzableiter, genannt ¤S¤ │ Antijupiter oder Tavernier’s │ gewitter-ableitende Säule. 8vo. _Leipzig_, =1833= │ =R= =S= │=Tedeschi=, A. Grundl. u. auf mehrfahr, │ beruh. Anleit z. Verfert. u. Erricht, d. │ Tholardschen Blitz- u. Hagel-Ableiter │ u.s.w. nach d. Ital. m. e. Anh. 8vo. 30 │ pp. 1 plate. _Prag_, =1825= │ =S=│=Tessier.= Observation sur l’effet du │ tonnerre à Rambouillet. 4to. _Paris_, =1785= │ ¤R¤ ¤A¤ │=Tetens=, J. N. Üb. d. beste Sicherung _Bützow and ¤S¤ │ einer Person bey einem Gewitter. 8vo. Wismar_, =1774= │ ¤S¤│ „ Another Edition. _Wismar_, =1784= │ ¤R¤ │=Thollard de Tarbes.= Moyena préservatifs │ de la Foudre et de la Grêle. │ =R= │=Thoresby=, R. An Account of a Young Man │ slain with Thunder and Lightning, Dec. │ 22, 1698. 4to. 2 pp. (_Phil. Trans._ xxi. │ for 1699, p. 51.) _London_, =1700= │ ¤R¤ │=Tieenk=, J. Bericht wegens de miswyzing │ van het compas, door den donders. │ (_Verhandel. van het Genootschte │ Vlissinqen._, iii. 615.) │ =R= │=Tietz=, J. Die Erfindung und erste │ Verbreitung d. Blitzableiters. 4to. 17 │ pp. (_Jahrsbericht über das Kön. Kath. _Braunsberg_, │ Gymnasium zu Braunsberg_, 1850–59.) =1859= │ =R= │=Tilas=, D. Von einem Donnerschlage in │ Oesterwahla. Kirchspiele und │ Waszmannlands Hauptmannschaft, im. J. │ 1740. 8vo. 6 pp. (_K. Schwed. Akad. Abh._ │ iv. 43.) _Hamburg_, =1742= │ =R= │=Tilesius von Tilenau=, W. G. Die Wirkung │ des Blitzes auf den menschlichen Körper │ durch einen merkwürdigen Fall erläutert. │ 8vo. 13 pp. 1 plate. (_Journ. f. Chem._ │ N.R. ix. 129.) │ ¤A¤ │=Toaldo=, G. Della Maniera di defendere gli │ Edifizii dal Fulmine. 8vo. _Firenze_, =1770= │ =R= │ „ Dell’ uso dei Conduttori metallici.... │ Apologia colla Descrizione del Conduttore │ ... di Padova. 4to. 32 pp. 1 plate. _Venezia_, =1774= │ =R= │ „ Del Conduttore elettrico posto nel │ Campanile di S. Marco in Venezia ... (1st │ ed.) 4to. 37 pp. 1 plate. _Venezia_, =1776= │ ¤R¤ │ „ Relazione del fulmine caduto nel │ Conduttore della Specola di Padova. (1st │ ed.) 4to. _Padova_, =1777= │ ¤R¤ ¤A¤ │ „ Dei Conduttori per preservare gli │ edifizj ... Memorie, in questa nuova ed. │ ritoccate ed accresciute di un’ Appendice │ ... 4to. 104 pp. 2 plates. _Venezia_, =1778= │ _Note._—This work contains his │ “Informazione al popolo” of 1772, │ including his translation of │ Saussure’s “Manifesto.” His “Dell. │ uso dei Conduttori ... Apologia ... │ of 1774, colla Descriz. del Cond. di │ Padova.” His “Del Condutt.... di S. │ Marco,” &c. of 1776. His “Relazione │ del Fulmine caduto nel Condutt. della │ Specola, Padova,” of 1777. His │ “Notizia del Fulmine ... nella Torre │ dell’ universita, Padova.” His │ “Appendice sui fatti ... recenti,” │ 1778; new matter. It also contains an │ Italian translation of Barbier’s │ “Considérations en général,” ... │ which is a memoir appended to │ Barbier’s French translation of this │ work of Toaldo. This Italian │ translation is by a printer, and not │ dated. │ _Note._—In his “Giornale │ Astro-Meteorologico,” for or of 1784, │ “Dei principali accidenti dell’ anno │ 1783.” The first division is headed │ “Della Nebbia, e della Influenza de’ │ Fulmini,” and in which he refers to │ much writing on these subjects by │ himself and others in the “Giornale │ enciclopedico di Vicenza.” │ =R= │ „ Fenomeno singolare d’un Fulmine │ descritto, e proposto all’ esame de’ │ fisici. 4to. 4 pp. (_Opus Scelti_, vii. │ 35.) _Milano_, =1784= │ =R= │ „ Appendice: Riflessioni sopra i colpi │ di Fulmine (alla Memoria del Marzari, │ “Descrizione d’una tempesta di fulmini.”) │ ... Letta 8 Feb., 1787. 4to. (_Vide_ │ Marzari.) _Saggi dell’ Accad. di Padova_, │ iii. 212, pt. i. _Padova_, =1794= │ =R= │ „ (or Anonym.) and =Saussure=. Della │ maniera di preservare gli edifizi dal │ Fulmine: Informazione al popolo. 4to. 19 │ pp. 1st edition. _Venezia_, =1772= │ _Note._—Annexed is his translation of │ Saussure’s Exposition under the title │ “Manifesto ossia Breve esposizione;” │ the paging being continued from 20 to │ 38. The date of Saussure’s work is │ Geneva, 1771. (See also Barbier de │ Tinan.) │ ¤R¤ ¤A¤ │=Tomlinson=, C. The Thunder Storm. An =S= │ Account of the Properties of Lightning, │ and of Atmospheric Electricity in various │ parts of the World. 8vo. 348 pp. _London_, =1859= │ =S=│ „ On Lightning Figures. (_Ed. New Phil. _Edinburgh_, │ Jour._) 8vo. =1861= │ =S=│ „ Further Remarks on Lightning Figures. _Edinburgh_, │ (_Ed. New Phil. Jour._) 8vo. =1862= │ =C= │ „ The Thunder Storm. 12mo. _London_, =1864= │ =R= │=Tourdes=, G. Relation médicale de │ l’accident occasionné par la foudre, le │ 13 Juillet, 1869, au pont du Rhin, près │ de Strasbourg. 8vo. 32 pp. _Paris_, =1869= │ ¤A¤ │=Trechsel=, F. Bemerkungen über │ Blitzableiter und Blitzschläge, │ veranlasst durch einige Ereignisse im │ Sommer, 1819. _Gilbert’s Ann._, lxiv. │ 227. =1820= │ │ ¤R¤ │=Unterberger=, L. F. von. Nützl. Begriffe │ von d. Gewittermaterie, nebst │ Beobachtungen üb. die beste Art, │ Blitzableiter anzulegen. 8vo. (_See │ next._) _Wien_, =1811= │ ¤R¤ │ „ Nützliche Anmerkungen von den │ Wirkungen der Electricität und │ Gewittermaterie. 8vo. _Wien_, =1811= │ │ │=Vaillant=. (_See Official Instructions, │ France._) │ =C= │=Vallemont= [L. L. de] Description de │ l’aimant qui s’est formé a la pointe du │ Clocher neuf de N. Dame de Chartres. │ 12mo. 215 pp. _Paris_, =1692= │ ¤R¤ │=Vassalli-Eandi=, A. M. Conghietture sopra │ l’arte di tirare i Fulmini appo gli │ Antichi. 8vo. (_Opuscoli Scelti di │ Milano_ in 4to. tom. xiv.) =1791?= │ ¤R¤ │ „ Nota sopra un mezzo facile di │ preservare le case rustiche dal Fulmine. │ (_Calend. Georg._ 1814.) =1810= │ =R= │=Vauquelin=, C. On Stones supposed to have │ fallen from the Clouds, (and discussion │ thereon) in the French National Institut. │ vo. 2 pp. (_Phil. Mag._ xv. 187.) _London_, =1803= │ =R= │ „ Memoir on the Stones said to have │ fallen from the Heavens. Read in the │ French National Institute. 8vo. 8 pp. │ (_Phil. Mag._ xv. 346.) _London_, =1803= │ ¤R¤ │=Vauquelin=, L. N. Mémoire sur les pierres │ dites tombées du ciel. 8vo. (_Journ. des │ Mines_, xiii. 1802–3.) _Paris_, =1802–3= │ ¤A¤ │=Verrati=, J. Dissertatione de │ Electricitati coelesti. 8vo. _Bologna_, =1755= │ =R= │=Viacinna=, C. Del fulmine e della sicura │ maniera di evitarne gli effetti. Dialoghi │ Tre. 8vo. 156 pp. _Milano_, =1766= │ =R= │=Vismara=, G. Dei fulmini che hanno colpito │ il torrazzo di Cremona. Memoria. 8vo. 24 │ pp. (_Extr. del fascicolo di_ Feb. 1841, │ _degli Ann. di Fisica, &c._) _Milano_, =1841= │ =R= │=Volpicelli=, P. Sulla necessità di │ proteggere dal fulmine le masse │ metalliche, stabilite nella cima degli │ edifici. Nota. 4to. 5 pp. (_Atti dell’ │ Accad. Pontif. dei Nuovi Lincei_, sess. │ i. del 3 Dicem. 1865, tom. xix. pp. │ 22–26.) _Roma_, =1865= │ │ =C= │=Walder=, E. Ueber wirkungsweise und _Nördlingen_, │ Construction der Blitzableiter. =1863= │ =R= ¤S¤ │=Walker=, C. V. Transac. and Proc. of the │ London Electrical Soc. Edited by C. V. W. │ 4to. _London_, =1841= │ =R= =S= │ „ The effects of a Lightning-Flash on (84) │ the Steeple of Brixton Church, and │ observations on Lightning Conductors │ generally. Large 8vo. 18 pp. 1 plate. │ (_Proceed. Lond. Elect. Soc._) _London_, =1842= │ =R= │ „ On the Action of Lightning Conductors. │ La. 8vo. 15 pp. 1 plate. (_Proceed. │ London Elect. Soc._) _London_, =1842= │ =R==C= │ „ Memoir on the difference between =S= │ Leyden Discharges and Lightning Flashes, (84) │ &c. La. 8vo. 42 pp. (_Proceed. Lon. │ Elect. Soc._) _London_, =1842= │ =R= ¤S¤ │ „ Proc. of the London Electrical Soc. │ 8vo. _London_, =1843= │ ¤S¤│=Walker=, C. V. The Electrical Magazine. _London_, │ Vols. i. & ii. =1845–46= │ ¤S¤│=Waltsgott=, J. F. De Fulgure, Tonitru ac │ Fulmine. 4to. =1734= │ =R= ¤S¤ │=Watson=, W. Experiments on Electricity. │ 8vo. _London_, =1746= │ ¤R¤ ¤A¤ │=Weber=, F. A. Abhandlung von Gewittern u. _Zurich und │ Gewitterableitern. 8vo. Leipzig_, =1792= │ =R= ¤A¤ │=Weber=, J. Die Sicherung unserer Gebäude │ durch Blitzstrahlableiter theoretisch und │ praktisch beleuchtet und bewahrt, samt │ einer Beurtheilung der Ableiter aus Stroh │ von Lapostolle. Eine Vorlesung. 8vo. 46 _Landshut_, │ pp. =1822= │ (127) =S=│=Weber=, L. Berichte ueber Blitzschläge in │ der Provinz Schleswig-Holstein. 8vo. 25 │ pp. 2 plates. =1880= │ =S=│ „ Berichte ueber Blitschläge in der │ Provinz Schleswig-Holstein. Zweite Folge. │ 8vo. 70 pp. 2 plates. _Kiel_, =1880= │ ¤R¤ ¤A¤ │=Wenzel=, C. A. W. Adhandlung über die │ Blitzableiter aus d. Franz. 8vo. _Wesel_, =1818= │ ¤R¤ │ „ Adhandlung über die Blitzableiter; aus │ d. Franz, frei übers. f. angeh. _Berlin_, │ Ingenieur-Officire. 2 Abtheil. 8vo. =1823–4= │ ¤A¤ │=Wharton=, W. L. The effect of a Lightning │ Stroke. 8vo. _London_, =1841= │ =R= │=Wilcke=, J. K. Die Meynungen der │ Naturforscher von den Ursachen des │ Donners. 8vo. 19 pp. (_Schwedische Akad. _Hamburg und │ Abhandl._ an. 1759, pp. 81 and 155.) Leipzig_, =1759= │ ¤S¤│ „ Von den Versuchen mit den eisernen │ Strangen, den Donnerschlag abzuwenden, │ und dem dabei beobachteten │ Merkwürdigoten. =1759= │ =R= │ „ Bemerkungen bey einem d. 30 May in │ Stockholm geschehenen Donner-Schlage. │ 8vo. 11 pp. 1 plate. (_Schwedische Akad. │ Abhandl._ an. 1770, vol. xxxii., p. 115.) _Leipzig_, =1770= │ ¤R¤ ¤C¤ │=Wilson=, B. Observations on Lightning, and ¤A¤ │ the method of securing Buildings from its │ Effects. In a letter to Sir Charles │ Frederick. 4to. 68 pp. (_Phil. Trans._ │ an. 1773, p. 49.) _London_, =1773= │ =R= │ „ Further Observations on Lightning. │ 4to. 26 pp. _London_, =1774= │ ¤R¤ │ „ New Experiments and Observations on │ the nature and use of Conductors. 4to. │ (_Phil. Trans._, pt. i. p. 245.) _London_, =1777= │ =R= ¤A¤ │ „ An account of Experiments made at the │ Pantheon, on the nature and use of │ Conductors; to which are added some new │ Experiments with the Leyden Phial. Read │ at the meetings of the Royal Society. │ 4to. 100 pp. 4 plates. _London_, =1778= │ ¤A¤ =S= │=Wilson=, R. Boiler and Factory Chimneys, (110) │ and on Lightning Conductors. 8vo. _London_, =1877= │ ¤A¤ │=Winkler=, J. H. Abhandlung von dem │ elektrischen Ursprung des │ Wetterleuchtens. =1746= │ ¤A¤ │ „ De avertendi Fulminis Artificio │ secundum Electricitatis doctrinam │ Commentatio. 4to. _Lipsiæ_, =1753= │ =R= │=Wittiber.= Über atmosphär. Electricität │ und Gewitter, insbesondere die Gewitter │ der Grafschaft. 4to. 23 pp. _Glatz_, =1860= │ ¤A¤ │=Wolff.= Versuche über Blitzableiter. =1801= │ =R= │=Woodcroft=, B. Patents for Inventions. │ Abridgments of Specifications relating to │ Electricity and Magnetism; their │ Generation and Applications. Printed by │ Order of the Commissioners of Patents. │ 8vo. 769 pp. _London_, =1859= │ ¤R¤ │ „ Patents for Inventions. Abridgments of │ Specifications relating to Electricity │ and Magnetism; their Generation and │ Applications. Part ii. A.D. 1858–1866. │ Printed by Order of the Commissioners of │ Patents. 8vo. 863 pp. _London_, =1870= │ ¤R¤ ¤S¤ │=Wucherer=, G. F. Von Anlegung d. │ Blitzableiter auf Kirchen u. anderen _Carlsruhe_, │ Hochgebäuden. 8vo. =1839= │ │ ¤R¤ ¤A¤ │=Yelin=, J. K.v. Über d. Blitzableiter aus ¤S¤ │ Messingstricken u. üb. d. am 30 Ap. 1822, │ erfolgt. merkwürd. Blitzschlag auf d. │ Kirchthurm zu Rosstall. 8vo. _München_, =1823= │ ¤R¤ ¤A¤ │ „ Über die Blitzableiter aus │ Messingdrahtstricken. 2e Aufl. 8vo. _München_, =1824= │ │ =C= =S= │=Zenger=, Prof. Symmetrische Blitzableiter. (104) │ 4to. │ ¤A¤ │=Ziegler.= Blitzableiter von Platina. │ Allgem. Handlungszeit. v. Leuchs 175. │ _Ann. de l’Indust. nation. et étrang., │ etc._ xviii. 320. =1824=

APPENDIX H.

APPLICATION TO AND REPLIES FROM THE LOCAL HONORARY SECRETARIES OF THE SOCIETY OF TELEGRAPH ENGINEERS AND CERTAIN OTHER DISTINGUISHED FOREIGN AUTHORITIES.

In accordance with a resolution passed by the delegates at the meeting on October 27, 1879, the following circular was prepared by the Secretary, and issued to the gentlemen named in the appended table.

30, GREAT GEORGE STREET, WESTMINSTER, S.W. _October 31st, 1879_

Dear Sir,—At the invitation of the Meteorological Society, delegates have been nominated by the following societies:—Royal Institute of British Architects, Society of Telegraph Engineers, Physical Society, Meteorological Society, to consider the present modes of erecting lightning conductors, and improvements therein.

At the last meeting I was instructed to ask you to have the kindness to furnish the conference with copies of such papers or reports as may be convenient, and as are generally accepted as authoritative in your country.

Yours very truly, G. J. SYMONS.

───────────────────────┬───────────────────────┬─────────────────────── NAME. │COUNTRY. │DATE OF REPLY. ───────────────────────┼───────────────────────┼─────────────────────── Allen, J. │Argentine Republic │ Aparicio, Don José │Spain │ Aylmer, J. │France │ Burton, C. │Bolivia │ Cantoni, J. │Italy │ Collette, J. M. │Netherlands │Nov. 7th. Cracknell, E. C. │New South Wales │ Dakers, J. │Canada │ D’Amico, E. │Italy │Nov. 16, Dec. 8. Delarge, F. │Belgium │ Field, S. D. │W. America │ Jamieson, A. │Mediterranean │ Karsten, G. │Schleswig-Holstein │Nov. 13. Madsen, C. L. │Denmark │Nov. 5, Dec. 7. Melsens, F. │Belgium │Nov. 6, Dec. 4. Michel, F. │France │ Morris, J. │Japan │ Myers, Gen. │United States │Dec. 13. Nielsen, C. │Norway │Dec. 1. Preece, J. R. │Persia │ Siemens, W. │Germany │ Teale, F. G. │India │Dec. 12. Todd, C. │South Australia │ Ward, G. G. │United States │Dec. 9.

The following are abstracts of the replies received:—

Nov. 5th, Copenhagen.—Mr. C. L. Madsen acknowledging receipt of letter and promising further reply.

Nov. 6th, Belgium.—M. Melsens acknowledging receipt, and promising full reply.

Nov. 7th, La Haye.—Mr. J. M. Collette acknowledging receipt of circular and stating that lightning conductors are not in common use in Holland, that there are no official and scarcely any other publications upon the subject. Those who have to erect conductors upon public buildings usually rely upon the rules adopted in countries where the use of lightning conductors is more general.

Nov. 13th, Kiel, Schleswig-Holstein.—Dr. Karsten forwarding copy of the latest edition of his work on lightning conductors (See Abstracts of Printed Documents, pages (114) and (119).)

Nov. 16th, Rome.—Sig. E. D’Amico acknowledged receipt.

Dec. 1st, Christiana.—M. C. Nielsen acknowledging receipt, and forwarding copy of paper by Prof. Mohn on “Lynildens Farlighed i Norgi.” (See Abstracts, page (106) which he states is the only paper on the subject printed in Norway.)

Dec 4th, Belgium.—Letter from M. Melsens, sending series of his works. (See Appendix G.; Catalogue and Appendix F. pages (137) to (141).)

Dec. 7th, Copenhagen.—Mr. C. L. Madsen writes:

“In continuation of my letter of 5th ult, I have great pleasure in forwarding a copy (enclosed) of ‘Regulations for the Arrangement and Construction of Lightning Conductors for Military and Public Buildings in Denmark, as adopted by the Royal Engineers, 1869,’ which I have translated from the Danish original, and obtained the permission to place at the disposal of the Conference. The rules laid down in this paper are generally accepted as authoritative in Denmark, and have been followed in the erection of Lightning Conductors on the new Royal Theatre in Copenhagen.

“I beg to add that in case a printed report is to be published by the Conference, I shall feel much obliged by having a few copies sent to me, and that I shall have great pleasure in continuing to have my attention directed to the subject.”

REGULATIONS FOR THE ARRANGEMENT AND CONSTRUCTION OF LIGHTNING CONDUCTORS FOR MILITARY AND PUBLIC BUILDINGS IN DENMARK, AS ADOPTED BY THE ROYAL ENGINEERS, 1869.

(_Translated from Danish._)

To obtain a perfect system of lightning conductors it is necessary to observe:

1. That the lightning conductor must be more exposed to the stroke of lightning than the building itself.

2. That the lightning, after having struck the conductor, shall traverse the conducting wire to the earth more readily than through any other neighbouring object.

3. That the lightning conductor is not destroyed by the stroke of lightning.

A. _Arrangement._

On the highest points of the building are placed _iron rods_, of such a length and number that no part of the building lies farther from the perpendicular line through the point of the rod, than twice the height of the point above the place of the rod. The lower ends of the rods are connected to a metallic conductor, _top conductor_, which follows the upper line of the building. From the top conductor, or from the rods, and at least from each three of these, _conducting wires_ are led down the roof and outer wall (best on the weather-side), and thence one foot under the earth, until about ten feet from the building. Here the wires are connected to the _earth plate_ in a well, the bottom of which well must reach a couple of feet under the lowest standing of the ground water. Each well, with its plate, ought at the utmost to serve three conducting wires. If necessary to employ more wells than one, the plates of these are joined up through a special conductor, the _earth conductor_, one foot under the surface of the earth. Great care must be taken that the earth plate is properly placed in ground water, that more or less communicates with the ocean—a condition which, in our country, will hardly present insurmountable difficulties.

Figure 1 shows a system of lightning conductors for a building 100 feet long, with gable roof.

NOTE 1.—If the roof is covered with metal, the conductors ought in several places to be connected to it; but, on the other hand, they must be kept, electrically, as distant from all other parts of the building as possible, especially from the metallic parts of it.

NOTE 2.—If ground water is found at a considerable depth, under a dry layer of sand, a second plate, besides the general earth plate, ought to be placed just beneath the surface of the earth, the latter being made temporarily conductive by rain.

NOTE 3.—As to powder magazines, which of course must be constructed of bricks or wood, the lightning conductors must not, without inevitable necessity, be placed on the building itself, but, retaining the above-mentioned dispositions in the main points (the top conductor excepted), they ought to be placed on masts, about ten feet from the magazine.

Figure 2 shows a system of lightning conductor for a powder magazine, a hundred feet in length, with gable roof.

B. _Construction._

_The point_ ought to consist of a solid copper cylinder, ¾ inch diameter, 6 inches high, conically pointed, the top angle being about 30 degrees, and with gilt top. At the lower end a nut is applied, by which the point is screwed and afterwards soldered to the end of the rod. Most conveniently the rod is formed of round iron, which, like the rest of the conductor above earth, if constructed of iron, is painted over or galvanized. Under earth only galvanized iron is suitable. The upper diameter of the rod is ¾ inch; 12 feet farther down, 1½ inch. The length is properly varying between 10 and 16 feet. It is to be preferred to use a greater number of low rods rather than fewer high ones. _The conductor_, as also the top and earth conductors, may consist of an iron bar, of ⅓ square inch section, consequently 9/16 inch in the square side, or ⅝ inch in diameter. Only for very great lengths will it be necessary, on account of the increased resistance of the conductor, to use thicker bars. In place of iron, copper may be used, the section of which need only to be ⅒ square inch. The conductors must be of as short a length, and with as few bends as possible; and the latter must be rounded at their angle points. They ought not to be bolted or spiked to the building, but, in view of changes of form occasioned by temperature or other reasons, they must rest in hooks, or be kept up by cramps that are fastened in wood or brick, far from the metallic parts of the building. It is of the utmost necessity that the conductor be continuous in its whole extent, from the point to the earth plate. Links of chains or cables are to be rejected. For this reason the number of joints must be limited, and a constant contact of the respective ends, extending over one or two square inches, procured by bolts or rivets and soldering. The metal should be filed on the contact sides, so as to clear it from oxide, this being an insulator, and the soldering made with tin. _The earth plate_ may consist of galvanized iron or copper. It ought to have at least a surface of 10 square feet in water, or 5 square feet area, if to serve one conductor; for each conductor in addition 50 per cent. must be added to the area. To diminish the circumference of the well, the plate may be given a cruciform transverse section; if then, for instance, the plate reaches 2½ feet down into the water, the wings need only have the length of 6 inches. _The well_ is constructed in the usual manner by digging or boring. In order to preserve the conductor from breaking, as the plate might press deeper into the ground, a beam is placed across the well’s upper part on which the horizontal part of the conductor rests. _Inspection_ of the lightning conductor must be effected once a year, and, besides, when circumstances demand it, for instance, after a stroke of lightning. The inspection must especially have the purpose:

1. To examine whether the metallic continuity remains perfect; to verify this a galvanometer is inserted, and a galvanic current led through the conductor; and

2. To examine whether the conductivity to ground water is in order. The earth plate being placed in a well, instead of being buried in the ground, will greatly facilitate this examination.

Dec. 8th, Rome.—Sig. D’Amico sent a copy of a letter received from Professor Tacchini, Director of the Central Meteorological Office, in answer to the communication made to him of the circular dated October 31st. The following translation has been kindly made by Professor T. Hayter Lewis:—

METEOROLOGICAL CENTRAL OFFICE, ROME. _November 27th, 1879._

LIGHTNING RODS IN USE IN ITALY.

Although I have not sufficient material for giving a complete answer to the request made in your letter, as noted in the margin, yet I think that the accompanying notice as to the system in use in Rome for fixing lightning rods may be useful to the Director General.

1. The conductor of the lightning rod is constructed of iron, 17 millimetres (c. ⅔rds. inch) diameter. The upper terminal or receiver is 4·5 metres (14 feet 9 inches) high, with a copper point 0·50 (c. 1 foot 8 inches), gilt from 0·25 (c. 10 inches), fixed on a pilaster of masonry 2 metres (c. 6 feet 6 inches) high, and 60 centimetres (c. 2 feet) wide. Each terminal is intended to protect a horizontal superficies of radius double its height.

2. In order to obtain a conductor as long as required, pieces of 5½ metres (c. 18 feet) are united by a holdfast of brass. The fastening of the conductor to the walls and roofs is made by little pieces of marble of the annexed form, connected with the fabric.

A—Wall or roof. B—Little piece of marble. C—Hole through which the conductor passes.

3. It is the custom to connect the conductor with masses of iron, and other metals in the building to be protected, avoiding the water pipes. (Referring probably to Terra Cotta pipes. T. H. Lewis.)

4. In addition to the upper terminal and chief receiver, it is usual to fix secondary points according to the form of the building.

5. The discharger or lower terminal (in contact with the earth) is made of copper rod, 12 millimetres (c. ½ inch) square, at least 6 metres (c. 20 feet) long, in 3 strips with points of copper arranged in the manner shown—

D—Conductor. E—Lower terminal or discharger with points of copper.

6. The discharger is introduced into a ditch or well excavated in moist ground, vertically or horizontally, according to the circumstances of the locality. The diameter of the well should be 0·80 metres (c. 2 feet 8 inches), filled with carbon, and covered with earth.

7. In an ordinary building we employ a discharger to each 3 points.

8. In this manner were made all the lightning rods of P. Secchi, by Signor Lerigi Morea, maker of them in Rome.

9. In some cases P. Secchi has made use, for the conductor, of the thicker wire used for the Telegraph.

10. We may observe that, in other Italian cities, the same rules are adopted for the construction of lightning rods, as I myself have verified. Only, in some localities, in place of putting points of copper to the lower terminal the latter is terminated by a copper band.

P. TACCHINI, _The Director_.

Dec. 9th, New York.—Mr. G. G. Ward acknowledges receipt, states that the only papers of any value upon lightning conductors, published in America and known to him are:—(A) a paper by Prof. Henry; (B) a treatise by Prof. Phin; (C) a pamphlet by David Brooks; (D) a practical treatise by H. Spang. The writer furnished copies of Nos. B and D, and all four will be found noticed in the Abstracts of Printed Documents. See pages (99) (102) (117) and (112.)

Dec. 12th, Calcutta.—Mr. F. G. Teale acknowledging receipt of circular and forwarding copies of two papers accepted as authoritative in India, viz:—(1) R. S. Brough on Protection of Buildings from Lightning, and (2) W. P. Johnston on the Lightning Conductors at Dum Dum. (See Abstracts, pages (117) and (132).)

Dec. 13th, Washington, U.S.A.—Lieut. Kilbourne acknowledges receipt on behalf of Gen. Myers, enclosing copy of paper by Prof. Henry, and stating that the works of Spang and Phin are considered authoritative.

APPENDIX I.

GENERAL CORRESPONDENCE.

TRINITY HOUSE, LONDON, E.C., _6th February, 1880_.

SIR,

I am directed by the board to transmit to you herewith, for the information of the Lightning Rod Conference, copies of reports made by Professor Faraday to this Corporation, one respecting a remarkable stroke of lightning which occurred at the Eddystone Lighthouse in January, 1853, and the other upon a similar accident experienced at the Nash Lights in August, 1852.

The case to which Admiral Sullivan directed the attention of the Conference, as stated in your letter of the 30th October last, was probably one of these two.

Should you desire any further details in connection with this subject, the Corporation desire me to assure you of the pleasure with which they will afford any information at their command.

I am, Sir, Your obedient servant, ROBIN ALLEN.

G. J. SYMONS, Esq.

[We have been favoured with copies of three separate reports by Professor Faraday, and think that it is better to give them in chronological order. There is only one other point in the correspondence from the Trinity House which it seems necessary to mention, viz., that the sections of the copper rods now used are as under.—ED.]

REPORT ON THE LIGHTNING RODS OF LIGHTHOUSES, 1843.

DUNGENESS.—Dungeness Lighthouse stands about 14 feet above the sea and measures 97 feet to the top of the lantern. The tower is of brick with wood floors; the roof and frame of the lantern are of metal seated upon a stone pedestal, to which it is secured. There is no conductor to the building. The weathercock is fitted with a glass repeller, and a rod similarly fitted is attached to the two copper flues which rise by the side of the lantern.

EDDYSTONE.—The height of the top of the lantern of the Eddystone above the sea is about 95 feet. The roof and framing of the lantern are of metal, secured through a stone plinth to the gallery of the tower by metal fastenings. A conductor of copper rod, ¾ inch diameter, is attached to the outside of the building; the rod rises 3 feet above the top of the lantern and terminates in the sea at low water; it is fixed to the tower and lantern by metal stays and fastenings and is isolated by glass ferules. To give stability to the building eight wrought iron ties are fixed in the interior of the house, extending downwards from the underside of the lantern floor through the next two stories, terminating by inserting the ends into the stone floor, the upper ends are riveted into an iron ring round the manhole in the ceiling and further secured by iron bolts passing through the stonework and communicating indirectly with the metal work of the lantern.

SPURN POINT HIGH LIGHT.—The Spurn High Light stands about 16 feet above the level of the sea, and measures 100 feet to the top of the lantern. The tower is of brick with wood floors; the roof and framing of the lantern are of metal, seated upon a stone plinth to which it is secured; the weathercock is surmounted by a glass repeller. An isolated conductor of copper rod, ¾ inch diameter, is attached to the outside of the tower rising some feet above the lantern and passing down the side of the tower below the surface of the ground.

SOUTH FORELAND.—The South Foreland High Light stands above 300 feet above the sea, and measures from the ground to the top of the lantern 67 feet. The tower is of brick, the lantern roof and framing are of metal with a cast iron pedestal; the weathercock is fitted with a glass repeller. A conductor of copper rod, ¾ inch diameter, is attached to the outside of the tower, of the same height as the weathercock. The rod is fastened to the lantern and tower with metal stays and fastenings, and passes into the ground, turning off at right angles to the tower a little below the surface. A copper flue connected with a stove in the base of the tower, passes up the centre of the tower through the roof of the lantern, to the lower end of which a copper rod has been attached, which is carried to the outside of the building into the ground.

The undersigned have, according to their instructions, met and considered the circumstances under which lighthouses are placed as respects lightning, and have arrived at the following conclusions:—

That lighthouses should be well defended from the top to the bottom.

That as respects the top, the metal of the lantern, and upwards, is sufficient to meet every need, and satisfy every desire and fear.

That for the rest of the course down the tower, a copper rod ¾ of an inch in diameter is quite, and more than, sufficient.

That at the bottom, where the rod enters the earth, it is desirable at its termination to connect it metallically with a sheet of copper 3 or 4 feet long by 2 feet or more wide; the latter to be buried in the earth, so as to give extensive contact with it.

That glass repellers are in every case useless.

That glass thimbles are not needed, but do no harm.

That if the repeller be removed, and the _point on the vane_ be terminated as the lightning rods usually are, and then the metal of the lantern be strongly attached to, and connected with, the upper end of the copper rod, and the rod continued down the tower to the earth, and the sheet of copper buried in it, such a system will be an effectual and perfectly safe lightning conductor.

That then there need be no rod end rising by the side of, and above the lantern.

That the rod may (if required on other accounts) come down on the inside of the building, or in a groove in the wall; but should not be unnecessarily removed from observation and inspection.

That all large metallic arrangements in the stonework, or other non-metallic parts of the tower of the lighthouse, such as tying bars, metal flues, &c., should be well connected, by copper, with the conductor.

That the vicinity of two metallic masses without contact, or metallic communication, is to be avoided.

That, as to the South Foreland High Light, the lantern, the central stove, and the copper rod proceeding from it to the earth, connected as they now are, form a perfect lightning conductor, even without the rod that is there erected; but

That it is important casual arrangements should never be depended upon for lightning conductors; but a copper rod be established for the especial purpose: for, if the former be trusted to, the carelessness or ignorance of workmen may, at after periods, upon occasions of repair or cleansing, cause the necessary metallic connection to be left imperfect or incomplete, and then the arrangement is not merely useless but dangerous.

That, as to the Eddystone, it is desirable to connect the system of wrought iron ties in it with the lightning conductor, by joining the lower part of that iron rod which is nearest to the conductor with the latter, by a copper rod or strap, equivalent to the conductor in sectional area.

That the Dungeness Lighthouse is in a very anomalous condition; to rectify which the two repellers should be removed, and also the representative of the top of a lightning rod attached to the flue, and that then a good copper conductor should be attached to the metal of the lantern, upon the principles already expressed.

(Signed.) M. FARADAY.

_25th September, 1843._

* * * * *

23, GT. GEORGE STREET, _25th September, 1843_.

SIR,

The reference, on the important subject of lightning conductors, is to Mr. Faraday and to me. On receiving it I prepared drawings of the buildings to which our immediate attention was required, with an explanation of their present conductors.

These were considered at a meeting with Mr. Faraday, when he explained the principles and their application to the several cases, deduced from his copious experiments and scientific observations.

I have since received from him the accompanying Report for my signature along with his, but the report is altogether Mr. Faraday’s and therefore I prefer adding my approval of all it contains in this separate sheet, and recommending that authority be given to me to act upon it.

I am, Sir, &c. (Signed) J. WALKER.

JACOB HERBERT, Esq. _Trinity House._

* * * * *

ROYAL INSTITUTION, _27th September, 1852_.

MY DEAR SIR,

I fortunately reached the Nash Low Lighthouse last Thursday, before any repairs were made of the injury caused by the discharge of lightning there, and found everything as it had been left: the repairs were to be commenced on the morrow.

The night of Monday, 30th August, was exceedingly stormy, with thunder and lightning; the discharge upon the lighthouse was at six o’clock in the morning of the 31st, just after the keeper had gone to bed. At the same time, or at least in the same storm, the flag-staff between the upper and lower lights was struck, and some corn stacks were struck and fired in the neighbourhood. It is manifest that the discharge upon the tower was exceedingly powerful, but the lightning conductor has done duty well—has, I have no doubt, saved the building; and the injury is comparatively slight, and is referable almost entirely to circumstances which are guarded against in the report made by myself and Mr. Walker 22nd September, 1843.

The conductor is made fast to the metal of the lantern, descends on the inside of the tower to the level of the ground, and passes through the wall and under the flag pavement which surrounds the tower. It is undisturbed everywhere, but there are signs of oxidation on the metal and the wall at a place where two lengths of copper are rivetted together, which show how great an amount of electricity it has carried.

A water-butt stands in the gallery outside the lantern. A small copper pipe, 1 inch in diameter, brings the water from the roof of the lantern into this butt; it does not reach it, but terminates 10 or 12 inches above it. A similar copper pipe conducts the surplus water from the butt to the ground, but it is not connected metallically with the other pipe, or with the metal of the conductor, or the lantern. Hence a part of the lightning which has fallen upon the lantern has passed as a flash, or, as we express it, by disruptive discharge from the outside of the lantern to this tub of water, throwing off a portion of the cement at the place, and has used this pipe as a lightning conductor in the rest of its course to the ground. The pipe has holes made in it in three places, but these are at the three joints, where, it being in different lengths, it is put together with tow and white lead, and where of course the metallic contact is again absent; and thus the injury there (which is very small) is accounted for. The pipe ends below at the level of the ground in a small drain, and at this end a disruptive discharge has (naturally) occurred, which has blown up a little of the cement that covered the place. Some earth is thrown up at the outer edge of the pavement round the tower over the same small drain, which tends to show how intense the discharge must have been over the whole of the place.

Inside of the lantern there are traces of the lightning, occurring at places where pieces of metal came near together but did not touch, thus at the platform where a covering copper plate came near to the top of the stair railing, but the effects are very slight. All the lamps, ventilating tubes, &c., remained perfectly undisturbed, and there was no trace of injury or effect where the conductor and the lantern were united.

Inside of the tower and the rooms through which the conductor passes there were and are no signs of anything (except at the rivetting above mentioned) until we reach the kitchen or living-room which is on a level with the ground, and here the chair was broken and the carpet and oil-cloth fired and torn. To understand this, it must be known that the separation between this room and the oil-cellar beneath is made by masonry consisting of large stones, the vertical joints of which are leaded throughout, so that the lead appears as a network upon the surface, both of the kitchen floor above, and the roof of the oil cellar beneath, varying in thickness in different places up to ⅓ or more of an inch, as in a piece that was thrown out. The nearest part of this lead to the conductor is about 9 inches or a little more distant, and it was here that the skirting was thrown off, and the chair broken; here also that the fender was upset and the little cupboard against the skirting emptied of its articles. If this lead had been connected metallically with the conductor, these effects would not have happened.

The electricity which in its tendency to pass to the earth took this course, naturally appeared in the oil-cellar beneath, and though the greater portion of it was dissipated through the building itself, yet a part appeared in its effects to have been directed by the oil cans, for though they were not at all injured or disturbed, the wash or colour in the wall above four or five of them was disturbed, showing that slight disruptive connections or sparks had occurred there.

At the time of the shock, rain was descending in floods, and the side of the tower and the pavement was covered with a coat of water. This being a good conductor of electricity has shown its effects in connection with the intense force of the discharge. A part of the electricity leaving the conductor at the edge of the pavement and the tower, broke up the cement there, in its way to the water on the surface, which for the time acted to it as the sheet of copper—which I conclude is at the end of the conductor—does, _i.e._, as a final discharge to the earth. Also on different parts of the external surface of the tower near the ground, portions of cement, the size of half a hand, have been thrown off by the disruptive discharges from the body of the tower to this coat of water: all testifying to the intensity of the shock.

I should state that the keeper says he was thrown out of bed by the shock. However, no trace of lightning appears in the bedroom, still there are evidences that powerful discharges passing at a distance, and on the other side of thick walls may affect bodies and living systems, especially by spasmodic action, and something of the kind may have occurred here. It may be as well for me to state that the upper floors are _leaded_ together like that of the kitchen. The reason why they did not produce like effect is evident in that they from their position could not serve as conductors to the earth as the lower course could.

The keeper said he had told the coppersmith to make the necessary repairs in the pipe, and I instructed him to connect the waste pipe and the upper pipe by a flat strap of copper plate. I would recommend that the lead of the lower floor be connected metallically with the conductor to a plate of copper in the earth. I could not see the end of the present conductor, not being able by any tools at the lighthouse to raise the stonework, but I left instructions with the keeper to have it done, and report to me the state of matters.

I am, &c., (Signed) M. FARADAY.

THE SECRETARY, _Trinity House_.

EDDYSTONE LIGHT.—REPORT _of_ PROFESSOR FARADAY _on Electrical Phenomenon which occurred thereat on the 11th January, 1853_.

ROYAL INSTITUTION, _24th January, 1853_.

MY DEAR SIR,

In reference to the remarkable stroke of lightning which occurred at the Eddystone Lighthouse, at midday on 11th January of this year, and made itself manifest by a partial flash discharge in the living rooms, I have to call your attention to the drawing herewith returned, and to the circumstances which appear (from it) to have accompanied and conduced to the discharge.

In the body of the stone work above the store-room exist eight rings of metal; each going round the building, and each being four inches square of solid iron and lead. Also, latterly the bedroom and sitting-room have been lined with a framework of iron bars, situated vertically, and pinned by long bolts into the stonework.

The part of the tower above the floor of the living-room is, therefore, filled with a metallic system, which, with the metal lantern, gives a very marked character to the upper half of the structure.

The recent metallic arrangements (but not the rings) are connected with the lightning rod; and the copper part of this rod, beginning at the floor of the living-room, then proceeds downwards by the course which can be followed in the drawing, and terminates on the outside of the rock between high and low water marks.

Considering all these circumstances, I was led to conclude that the conductor was in a very imperfect condition at the time of low water; and I had little doubt that I should find that the discharge had taken place when it was in this state, and very probably with a spring tide.

The day of the stroke was the 11th January—a new moon occurred on the 9th, so that it was at a time of spring tide.

The occurrence took place at midday; and, according to the tide tables, that was close upon the time of low water at Devonport. The end of the conductor would then be 6 feet from the water, if the latter were quiescent, and I cannot doubt that this circumstance gave rise to that diverted discharge which became so manifest to the keepers. Mr. Burges, with whom I have conversed about the matter, thinks it probable that, through the violence of the waves, the conductor does not now descend so much as is represented in the drawing.

I think it essential that the lower end of the conductor be made more perfect in its action; and I should prefer this being done on the _outside_ of the tower and rock, if the rod can be rendered permanent in such a situation.

If it be impossible to prolong and fix the lower end of the conductor where it now is, so that it shall have large contact with the sea at low water, then I would suggest, whether or no, on the more sloping part of the rock, about midway between high and low water, three or four holes could not be sunk to the depth of 3 feet, and about 3 or 4 feet apart, and that copper rods being placed in these, they should be connected together, and the lightning rod continued to them.

If this _cannot_ be done, then it might be right to consider the propriety of the making a hole through the centre of the building and rock, about 2 or more inches in diameter, and 30 feet deep, and continuing the conductor to the bottom.

A conversation with Mr. Burges regarding the present state of the Bishop’s Rock Lighthouse, now in course of construction, induces me also to suggest the propriety of making provision for the lightning conductor as the work proceeds.

It would be easy now to fix terminal rods of copper, and to combine them upwards with the work. Considering the isolated and peculiarly exposed condition of a lighthouse on this site, I would propose that there be _two_ conducting rods from the lantern, down the outside on opposite sides of the tower, each terminating below in two or three prolongations, entering as proposed into the rock, or into fissures below low water mark, so as to be well and permanently fixed.

I am, &c., (Signed) M. FARADAY.

THE SECRETARY, _Trinity House_.

[The present Eddystone Lighthouse, that is the stone one erected in 1757–59 from Smeaton’s designs, has a total height from low water level to the top of the vane of 107 feet. The annexed engraving shows two conductors, the old and defective one passing down the left hand side and terminating half way between high and low water level, and the proposed new one on the right terminating in holes in the rock.—ED.]

* * * * *

[The following letter would have been placed in Appendix A. along with the replies from British Manufacturers of Lightning Conductors; but it did not arrive until long after they had been printed off.—ED.]

Please find enclosed answer to your questions. In addition to manufacturing rods, we have been protecting buildings with these rods for thirty years. We sell in this way at retail from five to six hundred thousand feet each year. We also issue a guarantee of $500 (£100) on each building that we protect, which we hold ourselves ready to make good in case of failure. Now, in this extensive business, we have only had to pay one dollar damage done by lightning. We regard this as a practical demonstration that our method of protecting buildings with iron rods is as near perfect as it can be. There is more profit to be made out of the copper rod, as it is made cheaply out of sheet copper, and can be sold much higher than the iron rod. But knowing that iron for all practical purposes is the best material for lightning rods, we feel it to be our duty to do all we can to introduce it. We would most respectfully ask the Conference to investigate this question as to what kind of metal is best for rods for practical use, iron or copper. Our own late Professor Joseph Henry pronounced in favour of iron. We have many facts in relation to buildings being struck by lightning which we could give at some future time if desired. We have gathered up a large number of points that have been melted by lightning strokes. They are melted down about ½ inch. They all look as if the same amount of heat had been applied to each, showing very clearly that the quantity of electricity in lightning strokes is quite uniform. We have never in any instance known of the rod being melted, showing that the rod which we use is of sufficient size.

* * * * *

1 & 2. We make spiral twisted iron rods weighing 45 lbs. to the hundred feet [7¼ oz. per foot]. The rod is of the same sized material throughout its length, except that a copper point, plated with silver and tipped with platinum, is screwed on the upper terminal.

3. No proportion is observed between the length and sectional area.

4. Joints are made by means of copper nuts.

5. Attached to building by means of zinc strips, or a casting that fits closely to the rod, which is screwed down.

6. The rod extends from 9 to 10 feet in the ground.

7. A circle twice the diameter of height of rod above roof.

8. All terminals on the roof are connected. There are never less than two ground rods, and these are increased as the number of upper terminals are increased.

We also manufacture copper rods, but do not use them where we protect buildings, nor do we recommend them to other dealers from the fact that our experience of thirty years has demonstrated that iron is the best material for lightning rods.

COLE BROTHERS.

MOUNT PLEASANT, IOWA, UNITED STATES.

* * * * *

A colliery chimney near Sunderland, 180 feet high, was struck by Lightning, November 13th, 1878, and I was sent for to repair it. Upon getting to the top, which was about 15 feet diameter, I found a great many of the bricks displaced, and the upper terminal of the conductor (which was a tube 0·50 in. internal, and about 0·62 in. external diameter, and which had stood about 1 foot above the top of the chimney) had been fused and was lying on the top of the chimney, it was quite brittle, and easily broken by the hand. The upper 10 feet of ½ inch wire rope was in a similar state; it seemed as if it had been passed through an exceedingly hot furnace, and I rubbed it to dust in my hands. This 10 feet length was above the first holdfast, below the holdfast the wire rope was perfectly good. The holdfast was one of those which are driven into a wooden plug let into the wall and pinned tightly down on the rope, which had been badly bruised in the fixing—in fact, knocked almost flat. I believe that this was the cause of the accident, and that the lightning travelled down as far as this holdfast, and there meeting obstruction, returned destroying the wire and rod and shattering the brickwork. The earth connection was good, the end was buried in a trench 2 feet deep and 15 feet long.

T. MASSINGHAM.

NEWCASTLE-ON-TYNE.

* * * * *

I have been in communication with several of the principal brick builders here by whom the great majority of the chimney stalks in Glasgow and the west of Scotland are erected, and I believe the following statements may be taken as correct:—

(1) Very few stalks under ninety feet in height have lightning conductors, but, _as a rule_, the higher stalks have conductors. One of my correspondents says that “this rule holds good in four cases out of five.”

(2) A chimney being struck by lightning is an extremely rare occurrence in this district. One builder of long experience (Mr. McDonald) says, “I have known of several stalks that were struck by lightning, that had no conductors. I cannot point to one that was struck by lightning and had a conductor.” Another firm of old standing (Allan and Mann) say—“In our experience we have not known of a chimney stalk, with lightning conductor fixed, damaged by lightning.” Another firm (Bell, Hornsby and Co.) say—“In our experience we have not known an ordinary stalk with or without a conductor struck by lightning,” and Mr. Goldie says—“During the last twenty years I can remember only one such case,” and he is not sure whether the stalk had a conductor or not. There are three cases known to have occurred in Glasgow, but I never heard of any others among the hundreds—I may say thousands—of chimneys which are here. The great stalk at St. Rollox was struck shortly after its erection. A stalk at the works of Messrs. Alexander Paul and Co., was struck about nine years ago. Mr. Goldie makes the remark—and I think it is well worthy of notice—that in all these cases the accident happened shortly after the completion of the stalk. In these circumstances the stalk would still, no doubt, contain a large amount of moisture.

I think the St. Rollox stalk had a conductor fixed before it was struck, but I am not aware whether either of the others had.

Mr. Higginbotham (Todd and Higginbotham) tells me that the stalk at their works was struck before it was quite completed. It was _very slightly_ injured. It was afterwards struck as mentioned in my letter. On that occasion it had a lightning conductor.

The damage done was not very serious, but necessitated the binding of the stalk with numerous iron hoops—as thus strengthened it still stands. Mr. Higginbotham says that the opinion at the time was that the conductor saved the stalk from complete destruction, but that it was too small.

They, therefore, had it replaced by a much heavier one—copper rope ⅜th of an inch diameter, kept 1½ inches from the brickwork by glass insulators—which still remains.

J. HONEYMAN.

140, BATH STREET, GLASGOW.

* * * * *

There was no lightning conductor of any kind at Wells Church. The electric fluid struck the east side of the Tower just above the ridge of the nave roof. The tower stands, or stood, at the west end. I enclose an account of the fire from a local paper:—

WELLS.—TOTAL DESTRUCTION OF THE CHURCH.—“Near midnight of Saturday last, August 2nd, 1879, a terrific thunderstorm burst over this town and a large district around, causing most intense alarm and unfortunately ending in sad disaster. The storm raged throughout the night, and was accompanied in many places by a perfect deluge of rain. Between three and four a.m. of Sunday, the 3rd, it appeared to reach its height, the lightning being of a most vivid and alarming nature, and the thunder reverberating in continuous peals. A lull then occurred, but between five and six a.m. the storm again burst out with great fury, and at 5.50 the electric fluid struck the church on the eastern face of the tower immediately above the apex of the roof, driving out a large portion of the stone work, the flints flying hundreds of feet around. One large stone fell upon the roof of a house, near the east window, and penetrated to the room below, which was fortunately unoccupied; but the tenant, Mr. R. Wharf, who slept in the next room, was aroused, and one or two persons in the road seeing what had occurred, and observing smoke directly after issuing from the roof of the church, raised an alarm of fire, which quickly awakened the whole town.

R. M. PHIPSON.

NORWICH.

* * * * *

The first visible injury to Wells Church was the “skinning” of a portion of the tower (about 10 feet high by 5 feet broad) extending downwards from the east window of the tower (_i.e._, the window which looked over the roof of the nave,) to the point at which the lead-covered nave joined the tower. The lightning is believed to have set fire to the roof at this point, and also to have travelled along the lead roof to the chancel, and in crossing the vestry to have ignited the surplices, as the church was seen to be on fire at both ends before the middle was touched. The “skinning” was accompanied by great disruptive force, as the stones from the tower were not only shot the full length of the church, but one large one fell on the roof of a house 60 feet beyond the east end of the church.

WELLS, NORFOLK.

F. LONG.

* * * * *

As your questions in the _Times_ of to-day allude only to protection to _buildings_ from lightning, I need not say anything on the perfect protection afforded to Her Majesty’s ships by the conductors of Sir Snow Harris, from the time they were used in every ship in the service.

H.M.S. “Beagle,” Commander FitzRoy, was one of the first ships fitted with them. At Monte Video a heavy shock of lightning passed down the mainmast and through the ship without doing the slightest injury; but as the vane staff which tapered to a fine point, was fused at the point, it enables me to answer one of your questions. The copper was melted till the diameter was about one eighth of an inch, but below that point the conductor was not injured in any way.

You will like to know a case in which a copper wire acted as a perfect conductor, _though fused throughout its length_. It was at Monte Video, in the house of the English Consul, a flag-staff was struck, and conducted the lightning through a flat roof, near the bell wire of a suite of rooms (the wire ran in sight near the cornice) through a hole in each dividing wall, and then down to the bell in the basement; the wire was melted into drops like shot, which burnt a row of small holes in the carpet of each room. A dark mark, on the cornice above, showed where the wire had been. At the bell there was a slight explosion, and some little damage, but I do not recollect whether anything acted partially as a conductor from that point, and so carried off that part of the charge.

This, I think, shows that even an ordinary bell wire will act as a conductor for a rather strong stroke of lightning, as the large flag-staff was shattered.

I am anxious to call the attention of your conference to a point that it will be interesting to clear up. That is, whether a conductor should be a _solid_ rod, or in a shape to give the largest amount of _surface_ in the section? When I tell you that Faraday and Harris each told me that the other “knew nothing about it,” because they differed entirely on this point, I think you will see the importance of it. I had at the time to approve of the conductors for lighthouses. I will, if you wish it, give you more particulars on this point, as I believe it has never yet been settled: lighthouses having been fitted with Faraday’s, and ships and public buildings with Harris’ conductors. The one being a solid bolt, the other a hollow tube or double thin plates.

If Harris was right there is an unnecessary amount of copper in Faraday’s solid conductors; if Faraday is right, there is an unnecessary outlay in putting a given amount of copper into the shape of a tube, instead of using it as a solid rod.

B. J. SULIVAN, _Admiral_.

P.S.—You should get from the Trinity House particulars of a case in which, with a good solid conductor, the iron floor of a lighthouse, aided by some lead in the wall, diverted the lightning from the conductor, and caused damage inside. I think it was a Portland lighthouse, but it is so many years since that I may not be right.

TREGEN, BOURNEMOUTH.

* * * * *

Three or four years since, I was looking out of my office window in Finsbury, when a flash of lightning struck the tower of the church of St. Giles’, Cripplegate, towards which my sight happened at the time to be directed. As a portion only of the flag-staff, placed at one corner of the tower, was destroyed, I obtained permission to ascend the tower and discover the reason. I found a substantial copper rope conductor fixed in a somewhat careless fashion to the back of the tower, and passing some distance into the earth. This copper rope was about an inch in diameter, and was carried upwards, under and over several projections and cornices, and across the roof of the tower to its centre—where it stood erect, and evidently did its assigned work admirably. Clumsy and unsatisfactory as the fixing of this bent copper rope seemed to me to be, it is quite certain that it was most efficient; and had it not been for the flag-staff, capped with lead, which was carried up considerably higher than the copper rope, no evidence whatever of the lightning’s path would have been revealed. As it was, the discharge of lightning struck the leaden cap of the flag-staff, and descended down the wet, wooden pole, until the summit of the copper-rope conductor in the centre of the tower was reached, when the discharge flew across to the metallic earth conductor, leaving the lower part of the flag-staff unhurt, but shattering to splinters that portion which was higher than the summit of the copper rope.

RICHARD HERRING.

27, ST. MARY’S ROAD, HIGHBURY.

* * * * *

A small public-house of mine (the “Wheatsheaf”) stands at Trolley Bottom, in the parish of Flamstead, between St. Albans and Dunstable. On Wednesday, August 6th, 1879, about 2 p.m., during a storm, not otherwise very severe, my tenant was seated by the tap-room window (A on the plan) his wife being seated opposite to him, and having the window on her left, whilst she held her child with her right hand; there were at the same time in the room about five men besides. A sharp flash of lightning occurred, and the poor woman (when the smoke cleared away) was observed to have fallen backwards. She gasped twice, never spoke, and died immediately, and bore no further mark of injury, I understand, than a slight mark as of scorching on her neck, below the left ear. I fail to recollect whether her clothing was scorched or not, the child’s shoe and sock were both burnt, but she, herself, was unharmed. All present were sensible of an atmosphere heavily laden with sulphurous fumes; but, excepting as above, were absolutely unhurt.

On visiting the house about a week afterwards, with a view to its repair, I found a small round hole as if made with a bullet in a pane of the window (A) close to which the woman was sitting, but could discover no further injury either to the other panes, the window-frame, the floor, or anything in the room. In the parlour, B, the window-frame was violently wrenched outwards two or three inches, several of the panes were broken, one sash-line being scorched, as also the frame and linings in places, especially in the neighbourhood of the sash-weights (iron). The wooden chimney-piece E, was slightly moved from its position, the various articles upon it were scattered, and a bottle of ink which stood there, was thrown with some violence to the ceiling. The upper part of the chimney to that room, G, and a portion of the wall, of which it was a part, forming the gable end to the house were shattered, and at H a stout post, contiguous to the house wall, and supporting the roof of a lean-to, was split and wrenched from its position. The windows and frames upstairs, C D, were in the same state as that at B. The chimney, K, to the tap-room, was quite uninjured, and no harm was done to any part of the back of the house.

Flamstead is about four miles from Luton, and six from St. Albans, and stands on high land. Trolley Bottom is a hamlet half-a-mile distant, and is, as its name implies, low-lying. My house is, perhaps, the lowest in position there. It faces the North-West.

I fear that my experiences will be found to have but little bearing upon the main point you have in view, viz., the comparative merits of different descriptions of Lightning Conductors. I venture to think, however, that they are not altogether without interest as illustrating the effects of lightning in a by no means exposed situation.

I am writing only from memory what was told me at the time, and should you desire further information on any points, shall be happy to endeavour to obtain it for you.

It would interest me very much to know how it is to be accounted for that, whilst in the room in which the poor woman was struck, no further damage was done, other parts of the house were, comparatively speaking, wrecked.

JOHN EDWARD GROOME.

KING’S LANGLEY.

* * * * *

I was in a house at Cannes (France) belonging to my late father on the occasion of its being struck by lightning about five or six years ago.

The storm in which it occurred was a very short one, consisting of only four explosions, _every one_ of which took effect on some building in Cannes.

The rain was falling in torrents, and to this I consider we owed our safety as the shoots and stack-pipes being full of water acted as conductors. The villa stood high, but another building _very_ much higher, and on higher ground, was within 100 yards. The lightning struck the metal cowl of a brick chimney, which, being an addition, was led down outside the walls of the house.

In the explosion the front of the grate of the room to which this chimney belonged, together with fire-irons, &c., were all projected across the room (a large one), about 30 feet; but no marks of lightning having entered the room were apparent. In fact the lightning after blowing up this chimney, together with much of the roof and wall of the house (great portions of the solid masonry of which I found 50 and 60 yards off!) appears to have left the chimney and, taking the course of the iron shoot round the house, to have divided into _three_ streams, each of which ultimately found its way down a separate stack-pipe, melting in its way all the soldering of the joints, but otherwise leaving them uninjured.

One stream passed thus into a well, the door of which (locked the night before) was burst open, I presume by the sudden expansion of the air, another stream of the electric fluid passed into an underground drain, which it burst up, hurling into the air the trees planted above it, the third passing across a level asphalt roof, which it melted in spite of the water lying on it, descended into the earth harmlessly.

You will see by this that the amount of electric fluid must have been very great to require all these modes of dispersion, and it suggests the question whether the diameter of the ordinary conductors would be sufficient to carry off so great a stream. Of course, in this case, there was no conductor, and therefore no means of testing it.

H. RADCLIFFE DUGMORE.

THE LODGE, PARKSTONE, DORSET.

* * * * *

Thank you very much for the Pamphlet, which I have read with great interest. Messrs. W. & W. (page 6) state that conductors in masts (like Harris’s) are “most objectionable.” The best answer to that is: that while ships were struck in the Navy, and lives lost every year before they were introduced, no ship fitted with them ever received the slightest damage; and since all ships were ordered to be fitted—now about 30 to 35 years—I have never heard of the slightest damage, or the loss of one life—that fact upsets all theories on the subject!

Then connections between the higher and lower masts, and especially at right angles, are objected to on the ground that at a bend the conductor may be fused; such a thing was never heard of in the thousands of conductors that must have been fitted in the navy. Even if the movable plate were turned back the lightning following the longest conductor would leave one mast for the other, as the conductor went right over the mastheads, and the two conductors nearly touched each other.

At Spring Grove, near Isleworth, the church had a high spire which was fitted with a conductor, but the Vicarage was struck and some damage done to it, though, I think, much nearer to the tower than its height. I believe many are contented with one or two conductors to a building that should have many more. My small house here is about 70 feet long by 38 feet wide, and I have seven conductors—one to each chimney.

If it is once decided beyond dispute, that copper conducts in proportion to its _volume_; then a rod, or flat-plate, of about the proportions of one to four or five, for the purpose of fitting closer round projections, would be the cheapest and simplest form; but if it conducts in proportion to _surface_ then of course a tube, _double_ plate, or wire rope, would give the greatest protection at a given cost.

I firmly believe in the surface theory of Harris. I had been with him often when he made experiments nearly fifty years since, and witnessed a strip of tin foil of the thinnest kind, and about ¼ inch wide, protect a model mast of about six inches in diameter from electric shock, that without it split the mast to pieces, aided by a small hole through its centre filled with gunpowder. And I always thought that the surface-conducting theory of Harris was indisputable. But about 20 years since, having to approve a proposal of the Trinity House for a new conductor of a Lighthouse, which, like previous ones, was an inch in diameter copper rod called “Faraday’s Plan,” I thought I would go up to the Royal Institution and ask him why he did not use a copper tube instead, giving much greater conducting power with less copper. I did so, and he asserted positively that the conducting power depended entirely on the volume of copper in the section of the conductor, no matter whether it was in a bolt, plates, or tube; and that if Harris said differently, “He knows nothing whatever about it;” of course, I approved the rod conductor. But singularly enough, though I had not seen Harris for years, he came to town a few days after, and came to the Board of Trade to see me, and bring me a piece of his large tube conductor, with a connection, that he was fitting to the Houses of Parliament. When I told him what Faraday’s opinion was, he answered, “Then he knows nothing about it.” I was still inclined to believe in Harris; but a few years after, a young Indian R.E. Officer—Lieut.-Col. Stewart—whose death not long after was a serious loss to the service, was sent home to procure the electric cables for connecting different Indian ports. I was asked by the Secretary of the Indian Office to give him all the help I could. One day he came to me with a piece of the cable he proposed using. Inside the iron wires was a single stout copper wire about ⅒ of an inch in diameter. I asked him why he had not the central wire of several strands as usual, as I believed it would greatly increase the conductive power. He said that he had _carried out a number of experiments on this point_ before deciding; and that he was satisfied the conducting power depended on the _amount_ of _copper_ in the conductor, and consequently a solid wire was better than one of the same size made up by twisting small wires together.

This of course shook my confidence in Harris’ theory; but it is a point that can be easily decided by experiments on a larger scale; and I hope your Committee will be able to decide it finally.

Messrs. W. & W. prefer to a conductor on the masts a wire rope carried down from the truck, stopped to a back stay. The following fact will show its danger:—A French frigate, some fifty years since, had one so fitted as an experiment; while striking T.G. masts the conductor formed a large bight as the mast was lowered; a man standing on cap or cross-trees—I forget which—formed a shorter conductor between two parts of the wire rope and was killed without any other damage being done.

B. J. SULIVAN.

BOURNEMOUTH.

* * * * *

With reference to your recent letter in the “Times,” I shall be glad if you will inform me whether there has come under the consideration of the Conference the question of lightning conductors on board iron ships with _iron_ masts; for my part they would seem to be useless, and that if the iron mast have sufficient metallic communication, through the bottom, with the outside of the ship either by means of the screw shaft or in some other way; no additional conductor, copper ribbon, or strip, down the masts and along the decks over the ship’s side, or copper tube down the shrouds and over the ship’s side could be of the slightest benefit.

In some ships one or other of these arrangements has been adopted, and in others both have been applied at same time.

C. M. L. McHARDY.

FERN HILL COTTAGE, WINDSOR FOREST.

* * * * *

I have observed your letter in “The Architect” of Saturday last. With reference to the subject on which it treats, I chance to have noticed since my residence here (a period of eight years) what I suppose to be an unusual frequency of lightning striking objects immediately round this spot, and the neighbourhood generally.

This inference is suggested by the fact that within the period mentioned lightning has fallen within fifty yards of the same spot three times—that this summer (one of those occasions) two other houses, both (say) within 500 yards in a direct line from this spot, were also struck—and generally, I believe, more objects are struck in this neighbourhood than usually happens to be the case.

My idea may be a fallacy, for I have no sort of statistics by which to test it; but if you suppose it is not so, and if such points come within the scope of your inquiry, I should be glad to send you a map marked with the spots where, and the dates when, lightning has fallen in or near this town. The only local peculiarities I notice are: 1. An unusual number of houses close to this have lightning conductors (a mere coincidence, and not placed there on any impression like my own). 2. We are at the bottom of a deep bay of parabolic plan which may influence the movements of electrical disturbance. 3. A soil of sand and gravel containing much oxide of iron.

A. BALDRY.

ATHELNEY, BOURNEMOUTH, HANTS.

[Mr. Baldry kindly supplied the map, and we find that a half circle of half a mile radius struck from the cliff-edge half a mile west of Bournemouth Pier includes the churches of St. Peter, with one conductor, and Holy Trinity with three; eight private houses with conductors, of which four houses have one each, and the other four have two, five, six and seven respectively, and within this area six objects are known to have been struck—three in the year 1879, two in 1871, and one in 1870. We do not know of any English locality where there are so many houses with conductors; but there are many more remarkable cases of repeated injury within small areas—_e.g._, in one storm in June, 1878, there were at least eight separate buildings injured within a circle of half a mile radius struck from the Metropolitan Cattle Market in the north of London.—ED.]

* * * * *

It occurs to me that it is worth while for the delegates of the Royal Institute of British Architects to raise the question, and, if possible settle, whether or not the gas pipes which permeate many buildings might or might not be utilized as lightning conductors; and whether any risk of gas explosion would be incurred thereby.

In my own practice there occurred the case of a lofty building, with a domed roof, and a sun-burner with a 1½ inch gas-pipe to supply it, rising to the summit of the dome, and a large iron cowl over the sun-burner.

The same circumstance occurs in most modern theatres. If the cowl were struck by lightning there was perfect metallic connection thence to the street gas mains—and one of larger sectional and superficial area than an ordinary lightning conductor would give.

H. D. DAVIS.

2, FINSBURY CIRCUS, CITY, E.C.

* * * * *

Lightning conductors have been a great hobby with me for many years, and I have induced a great number of clergymen and others to fix them to their towers and houses. During my time in the navy and merchant service I witnessed many fearful effects of lightning, and for the last thirty years I have been striving to persuade my friends to secure their houses from these terrific visitations. On the 24th December, 1699, the upper half of the fine steeple of this town was hurled to the ground, and a large portion of the church broken in. Pinnacles were then substituted for the upper portion of the steeple, to which I have had an efficient conductor attached. As far as I can gather from records, and from the abortions so frequently substituted for the original pinnacles of towers, I have come to the conclusion that _nearly every tower in this country_ has been struck by lightning during the last 400 years, when nearly all the towers were built. Many years since, the Illustrated News gave a sketch of a beautiful steeple (in Norfolk, I believe) destroyed by lightning. It was stated that this was the second steeple which had met with so sad a fate. After the destruction of the first, a second steeple was built by subscription, at a cost of £1,000, and the scaffolding had been removed only ten days when, during a terrific thunderstorm, this second steeple was entirely destroyed! I wrote immediately to the incumbent to ask about the _conductor_, and his answer was that none had been fixed, but that it was quite decided that an efficient one should be attached to _the third steeple_! This would almost appear incredible, and I regret that I did not dot down the name of the Parish and other data, but I think it was about 20 years since.

The conductors I recommend are simply copper rods of ¼ inch diameter, attached to the highest chimney, and brought to the ground two or three feet under the surface. When buildings are longer than they are high, I always advise a conductor at each end. I generally place the conductor four or five feet above the chimney, and bring it out from the base of the building. Where a steeple or pinnacle has a vane it is only necessary to fix the conductor to the base of the spindle. Sir W. Snow Harris recommended much heavier copper conductors, but their great expense has prevented their adoption. The old conductors in men-of-war were composed of long copper links, of which nine feet went to the lb., and these were _always_ efficient _when in place_. Now of ¼ inch copper rod there are only _five feet_ to a lb., so that I give a larger margin for security.

JAMES LIDDELL.

BODMIN.

* * * * *

I observed your notice that you required information in reference to lightning and lightning conductors. A case was brought to my attention last year which occurred in Middlesborough. I enclose you particulars of the same extracted from my report, together with a tracing shewing the elevation and plan of the chimney shaft which was struck with lightning.

BALDWIN LATHAM.

7, WESTMINSTER CHAMBERS, VICTORIA STREET, S.W.

A. Wooden cover over boiler. B. Boiler. C. Iron disinfecting apparatus. D. Iron flue into chimney. E. Conductor. * Position of fracture.

_Extract from a Letter from Mr. E. D. Latham, C.E., Borough Surveyor of Middlesborough, dated October 11th, 1878, with reference to the striking by lightning of the chimney in connection with the washhouse at the Middlesborough Fever Hospital at Linthorpe_:—

“The chimney, which is a brick one, is about 50 feet high and 5 feet square at the base and stands at the north end of the washhouse, as shown on the accompanying sketch. The conductor, a ⅜th inch copper rope, is fixed on the south side of the chimney with holdfasts, no insulators, and finishes in the usual manner, about 2 feet above the top. The conductor is carried under the ground for a distance of about 9 feet from the chimney, and terminates at a depth of about 4 feet in hard, rather dry clay, the end being wrapped about three times round a common brick buried in the ground. At a distance of about 9 feet above the ground at the same side as the conductor, and only about one foot from it there is a fracture in the brickwork where the electric fluid appears to have penetrated the chimney and gone a short distance down the inside, to the flue connected with the iron disinfecting apparatus, which stands at the side of the clothes boiler, as shown on the plan. The stone work of the top of the boiler was broken and other damage done.”

_Extract from the reply of Mr. Baldwin Latham, C.E., to the above communication_:—

“It is no uncommon thing for buildings provided with what are called lightning conductors to be damaged by lightning, and the cause is due to the inadequacy of the conductor to carry the electric fluid, which will leave the conductor for a better or a larger conductor. Wire ropes are found to be one of the worst forms, the same amount of metal when applied in a solid rod or ribbon is far more efficient, as it offers less resistance than the strands of a rope. You say your conductor is perfect, but by examination of the drawings it will be seen that the lightning descended the conductor to a certain point. At this point the iron flue enters the shaft, but some distance from the conductor; the mass of metal located there was a better conductor than the rope, so that in leaving the rope for the better conductor, the electric fluid passed through the brickwork and caused the damage. If the boiler and flues did not join in metallic communication, damage would arise from the fluid passing from the flue to the boiler, and if the boiler were not in metallic communication with the earth, farther damage would arise when the fluid left the boiler for the earth. It is well known that electricity of high tension will leave small conductors for large ones, and the knowledge of this fact is made use of in protecting the telegraph system throughout the country. Many buildings and chimneys have been struck that have been fitted with so-called lightning conductors. A perfect system of protection against lightning consists in linking together all the conductors about the buildings. Such was the system introduced by Sir W. Snow Harris and adopted by the Government.”

* * * * *

_Reply of Dec. 12th, 1878, acknowledging receipt of Mr. Baldwin Latham’s Letter._

“I am directed by the Town Council to tender you their thanks for the trouble you have taken, and the valuable information you have given with reference to the lightning conductor at the Middlesborough Fever Hospital.

GEORGE BAMBRIDGE. _Town Clerk._

CORPORATION HALL, MIDDLESBOROUGH.

* * * * *

_Subsequent action._

At the suggestion of the Engineers of the Telegraphs in the district, the earth portion of the rope has been imbedded in a mass of coke, and a quantity of old iron has been placed at the bottom of it, to counteract the influence of the boiler and disinfecting apparatus.

I beg to report an incident which occurred on board the barque “Southern Queen,” from Pensacola, while coming up Channel on the morning of the 30th of December, 1879, the Eddystone Lighthouse bearing about north, dist. 20 miles. At 6 a.m. of the above date, saw a terrific squall rising in the W.N.W. point of the horizon, with vivid Lightning in it.

We immediately reduced sails down to lower topsails and foresail, and about 7 a.m. the squall of wind and hailstones overtook us: it blew furiously for about twenty minutes, and in the height of the squall a thunderbolt broke on the ship, shattering the main royal mast-head, thence the Lightning ran down the main royal stay to the fore topmast head, and shattering that also. Thence it ran down the chain of the fore-topsail haulyard and shattered about a fathom of the chain in bits. When the bolt struck the ship it made a report like a hundred ton gun fired off. The concussion on the ship threw every man off his feet. It filled the cabin with smoke, and also the hold: the smoke had a sulphury smell; also all the compasses in the ship were so magnetized that they were flying right round.

And on arrival into the Commercial Docks we observed that a plank on each side of the ship, in the wake of the main chains, had been blown out by the Lightning. On the port side the oakum has been blown out of the seams, and the edges of the planks shattered. Since the ship has lightened up out of the water, we have discovered that the electric fluid has passed out by a copper bolt, cut the copper sheathing in the shape of a star, and turned it back.

Any further particulars I will be most happy to supply if required.

D. MORGAN, _Master_, “_Southern Queen_.”

17, LIME STREET, LONDON.

[Two of the delegates visited the ship, but with the exception of learning from the mate that he saw “a ball of fire descend from the mizen and go over the port side” they had not been able to obtain any additional particulars. They obtained some fragments of the broken chain, a much rusted iron one, weighing however about two pounds per foot.—ED.]

* * * * *

The patterns of lightning conductors obtained from Messrs. Hart, as requested, are an improvement on the first “Spratt’s Patent” purchased by the above-named firm; the original was a mixture of copper and zinc wire, which, when it was exposed to a wet and smoky atmosphere, a galvanic action took place and soon destroyed it.

About two months ago I engaged Messrs. Davis, of Derby and Newgate Street, to test a rope of the above construction that had been fixed about ten years at No. 1, Aberdeen Terrace, Blackheath, and I was present at the time, and though we had a very powerful battery we could not get a current through any part of it, as both the copper and zinc had decayed: the copper wire is not stout enough to allow for corrosion in this climate.

St. Michael’s Church, Blackheath Park, with the needle spire, as we call it—built just fifty years ago—had a ½ inch iron rod; and as it now runs through the new vestry just built I have advised the churchwardens to have it tested, and they are going to have it done in the course of a week or so.

St. Alphege Church, Greenwich, has a ribbon of copper about 1½ inches wide by ¼ inch thick, and that has been up many years, and is as sound as when it was fixed, for I examined it about two months ago.

I have advised the owner of No. 1 Aberdeen Terrace, to have a ribbon of copper, as I am certain that wire ropes are not to be depended on in this climate.

Hoping these few remarks will not be deemed out of place,

CHARLES J. HERYET.

95, BLACKHEATH HILL, GREENWICH, S.E.

* * * * *

I have the honor to forward notes of an accident from lightning, which I lately witnessed, having been informed that your Committee desires such information.

The very rough sketch which I attach is, I believe, accurate; but I was only allowed to look in at the door while a strong light was held within, and to view the outside of the building. A native draughtsman belonging to the office, however, was allowed to make some measurements, which he communicated to me.

It seemed to me that the case was worthy of record, because the building was so little injured.

JOHN ASTED, Lieut.-Col. R.E.

MASULIPATAM, MADRAS PRESIDENCY, _17th May, 1878_.

_May 8th, 1878._—Camped at Pedda Kondur, a village on the west bank of the Kistna river, about 10 miles below Bezoarah anicut. All the morning there was a southerly wind blowing unsteadily; by noon it fell calm, and was very hot, clouds gathering in the east. Soon after midday thunder was heard to the east, and a storm was evidently approaching. About 3 p.m. wind began to blow from the east, and soon rose to a gale, bringing thick clouds of dust, and the thunder sounded very near. It rained rather heavily, which laid the dust, and black clouds could then be seen over-head, and nearly all round: the thunder, which was very loud, sometimes sounding quite over-head. By half-past four the rain had slackened, but thunder was almost incessant, and very loud. Just at this time a stream of lightning descended within 80 yards of the tent, and was accompanied by a tremendous explosion. The lightning struck a small pagoda near the village, and some of the natives said that they observed smoke rise from the summit when the lightning descended.

The accompanying rough sketch will show what the building is like. The main part of it is a square pyramid, each side of the square, outside measurement, being about 18 feet; height of apex above ground, 32 feet. Built on to one side of the pyramid is an entrance chamber, with flat roof, about 10 feet square, and the same in height. The apex of the pyramid is surmounted by a metal (probably copper) finial, about 1 foot in height; the ordinary attachment of such a finial to masonry is by means of a small stake built into the masonry, on which the finial—which is cast hollow—is fixed, and round which it is plastered with mortar.

The interior of the pyramid forms one room, about 10 feet square, with a domed ceiling, the thickness of the dome at crown being 2½ feet. In the centre of this room is placed the idol, in this case a lingam, or cylindrical stone pillar, 1 foot 4 inches high, and about 9 inches in diameter, which stands on a square hollow stone tray (not cut out of one stone, but fitted in two or more pieces) in which the offerings of ghee, &c. are placed. This tray has a small spout on each face to carry off the liquid ghee and water with which the priests’ ablutions are made. The tray is raised on masonry, so that the height of the top of the lingam is 3 feet 4 inches from the floor. The floor of the room is 1 foot above the surrounding ground; there is only one doorway leading from the porch or entrance room above mentioned; and the sacred edifice is closed by a substantial wooden door, with iron hinges and lock, on the outer face of the entrance chamber. The whole building is of brick in mortar, unplastered, and presents the appearance of being weather worn.

The pagoda is at a distance of about 20 yards from some low native houses, and stands in an open space, on two sides of which is the native village; round the houses are some trees, mostly of small size, but within 50 yards of the pagoda are two separate trees, which certainly exceed it in height. The village is situated on the margin of the Kistna river, and the surface of water in wells is at least 10 feet below the surface of the ground.

The lightning struck the metal finial on the top of the pagoda, and passed vertically through the dome, travelled along the east side of the lingam without leaving any mark, and bored a small round hole in the stone tray beneath it, passing into the ground below without disturbing the idol or its foundation. The hole in the tray was not quite large enough to admit the point of a little finger, and it was situated on a joint of the stone, a place where moisture would probably linger. The finial appeared undisturbed, but the masonry immediately round its base was shattered, and a shower of pieces of brick and mortar was sent from the top of the pyramid and scattered over the ground on the east side to a distance of about 20 feet from the base. The masonry of the apex of the pyramid was cracked in three places, and a small hole was bored in it, on the east side of the finial, apparently about the same size as that in the stone tray; but otherwise the masonry of the building appeared totally uninjured—not a crack could be found anywhere.

The soil at this place is a clayey loam, rather lighter than the ordinary delta alluvial soil.

When the building was struck a sulphurous smell was noticed.

JOHN ASTED, Lieut.-Col. R.E.

MASULIPATAM, _17th May, 1878_.

* * * * *

IRISH LIGHTS OFFICE, DUBLIN, _13th March, 1880_.

SIR,

Adverting to your letter of the 13th ultimo, I have now the honour to forward herewith for the information of the Lightning Rod Conference copies of two Reports relating to the lighthouse at Berehaven being struck by lightning, in 1877, which, no doubt, is the Station alluded to by Professor Tyndall in his conversation with Mr. Inglis, of the Trinity House.

I am, Sir, Your obedient Servant, W. LEES, _Secretary_.

* * * * *

IRISH LIGHTS OFFICE, DUBLIN, _February, 1877_.

SIR,

I most respectfully beg leave to state that, in accordance with your instructions I proceeded to Berehaven Lighthouse, and on my arrival at that station I made a very careful examination and found that the lightning was conveyed into the lantern by the iron stay bars that were connected to the lightning conductor at a collar about 5 feet over the gutter on the outside of the dome for the purpose of securing it, and bolted to the dome of lantern by iron bolts. After bursting off the several coats of paint at the heads of the bolts, it put out the lights, breaking the glasses, and knocking down both light keepers insensible; it having twisted off the lead voice-tube where it was secured to the side of the lightroom by a holdfast, bursting out the stone sheeting between the iron pillars supporting the marble top; it then passed through the voice tube to the principal keeper’s bedroom, where it burst out the studding and lath and plaster, and tearing away the voice-tube, the foot-board of the bed, and destroying the pictures that were hanging on the walls. It would appear that the current was interrupted in its course by the sudden bend of the voice-tube; for, after having dealt destruction in this apartment it was attracted by the iron holdfasts and spikes that secured the voice-tube and studding to the walls, and passed out through the external walls of dwelling to the out offices, where it passed along the eave gutters to the end of them; it then followed one of the iron holdfasts, and entered the wall, destroying it, and bursting out the cut-stone kneeler and barge course, it then passed down through the roof of the low buildings, destroying the slating, passing through the walls of the pantry, &c., tearing up portions of the 3 inch Yorkshire flagging of the floor and yard, dealing destruction to the shelving, doors, door frames, brickwork, glass, &c., and bursting up the seat of principal keeper’s w.c., it passed along the sewer to the assistant keeper’s w.c., breaking up the flags and seat and then passed out through the roof. Another current was attracted by the eave gutters at the east angle of the dwelling near the tower, and passed along them to the north east angle, splitting them through the centre. At this point its course was changed to the west, and passed into the assistant keeper’s yard and down the rain water pipe to the water tank, splintering it and the slating and brick wall, &c.; it also appears that the lightning struck the south-east side of the tower and entered it in several places at the base and near the lightning conductor, and apparently glanced off it where it was secured by holdfasts to the tower, rooting up the solid rock, but giving no indication that it had been conveyed to earth by the conductor as intended: the lightning also entered the assistant keeper’s kitchen through the chimney, knocking down a portion of the brickwork, &c.

I may remark that the lightning conductor is formed by a copper rod, which stands about 10 feet over the gutter on the outside of the lantern, and is secured by three iron stays to the dome, as before described, and passes down through the centre of the gutter to the under side, where it is connected to a ½-inch copper-wire rope, which continues down the outside of the lantern close to the glass to the floor of the balcony, passing through the stone floor by means of a hole, jumped through it, then continues down the face of the tower closely pressed to it by the iron holdfasts and copper bands, which secure it until it reaches the rock at the base of the tower, where it terminates in a small hole 3 inches by 3 inches, jumped out of the rock about 6 inches under the surface.

After having made a careful survey of the damage done, I deemed it advisable, and at the solicitation of the principal keeper, who seems to have been greatly shaken and nervous, to have the iron stay-bars disconnected from the dome of the lantern and the bolt-holes plugged up with timber, fearing a recurrence of the accident, as the weather was very stormy, and should lightning come on no person on the rock would enter the lantern. I also considered it prudent to have the loose gutters and cut-stone, also a part of the gable of the out offices, taken down, as it was in danger of falling into the narrow yard, which might cause a sad accident.

Having provided workmen and materials and scaffolding for doing this work I again landed on the rock on Saturday last, with great difficulty, having been detained a day by the storm, and pointed out the temporary repairs that were necessary to be done for the protection of the people on the rock.

The probable cost of repairing the damage done the buildings, independent of the lightning conductor, and which require to be done without delay, will be £120. Hoping the action I have taken in this matter will meet with your kind approval, I have the honour to be

Your most obedient Servant,

(Signed) A. J. BERGIM.

[The other report is to the same effect as the above, and is therefore omitted.—Ed.]

* * * * *

ACCIDENT BY LIGHTNING _at Upwood Gorse, Caterham, the residence of_ J. TOMES, Esq., F.R.S. _28 May, 1879_.

As I happened to be visiting Mr. Tomes, in the autumn of 1879, I took the opportunity of obtaining all the particulars I could with reference to the accident which occurred on the night of the 28th May, 1879, when his house was struck by lightning.

The house, a sketch plan and elevation of which are annexed, stands upon a hill upwards of 700 feet above sea level, and is somewhat higher than any other object in the vicinity. It is covered by a steep tiled roof, that of the principal portion of the house being somewhat higher than the rest, and upon the ridge of this roof stand two brick chimney stacks of equal height. Upon the eastern stack, at its southern end, was fixed a lightning conductor (shown by the line, A. B. C., on the south elevation), the upper part consisting of a point and a length of copper tube ½ an inch external and ⅜ inch internal diameter, which was screwed into a collar connected to a woven band of one zinc and thirteen copper wires carried through glass insulating rings along the slope of the roof, over the rain-water gutters and down the side of the house into the ground, going only 12 inches into dry chalk.

The electric fluid struck the lightning conductor, hurled the rod down and shattered the chimney pots and some of the brickwork. The rod was broken at the point marked A on the south elevation, where the sectional area of the copper rod was reduced by the screw being cut into it for the collar, which connected the rod with the woven band. This junction and a portion of the band are forwarded for inspection, from which it will be seen there are no rough broken surfaces, but that the thread of the screw was partly melted. The copper wires composing the band were bright and nodulated here and there throughout their length, showing that it had been heated up to a sweating temperature. The zinc wire was not continuous, having been wasted by oxidization. It showed no indication of having been hot.

Having broken the conductor, the discharge appears to have divided at the ridge of the roof, a portion passing down the southern and a portion down the northern slope of the roof. That portion which passed down the southern slope apparently followed the course of the conductor band as far as the iron rain-water gutter, which it cracked, and perforated two holes, about half an inch diameter, in two panes of glass at B. Here the current apparently again divided, as shown by the dotted line from D to E on the south elevation, some passing westwards and some eastwards along the rain-water gutter round the eaves of the house, as traced by the broken joints of the gutter. Westwards these joints (which were made of red lead) were only broken from B to D, but eastwards they were broken from B to E, and right round the eastern side of the house to F, and along the northern side as far as G.

What seemed to be the greater portion of the discharge, however, passed down the northern slope of the roof and along the course shown by the dotted lines on the Plan and north elevation. The lightning first followed the lead flashing H of the chimney stack, next broke some tiles at I, and then without disturbing any of the rest of the tiling, leapt across the roof, a distance of some 15 feet, to two galvanised iron water cisterns in the roof at K, perforating a hole through the 9–inch brick wall of the house in its course.

This hole, which was circular, was large enough to admit one’s finger easily and was blackened on its interior; when first examined, eight or ten minutes after the occurrence, it was still quite hot. One edge of the lead flashing outside the wall was fused at G, close to the rain-water gutter, from which it would seem that the current again divided at the wall of the house. There are two galvanised iron cisterns at K, connected by a pipe underneath (see adjoining sketch plan), and the discharge appears to have passed from one cistern to the other and then along the 1½ inch iron barrel rising main, from pumps, to the point L^1 in the back kitchen, where the iron pipe separated into two branches leading to the two pumps L^2 and M.

Probably a portion of the discharge passed down the iron suction pipe from the pump L^2 into the rain-water tank P, but however this may have been, a considerable portion passed from point L^1 along the 1½ inch iron pipe LM to the pump M in the scullery, and thence along a ¾ inch iron pipe to a water tap fixed over the iron sink N, but not in metallic connection with it. Here the lightning broke the slate at the back of the sink and sent it showering across the scullery, breaking the things on the opposite side of the room. The iron sink was set on brick piers and connected, by means of a 1½ inch iron pipe, with the self-acting syphon “Flush Tank” O in the yard. This “Flush Tank” consisted of a cylindrical cast-iron tank about 26 inches in diameter and 26 inches deep, buried two-thirds in the ground, so that it formed a fair earth connection.

There is an account of the accident in a letter by Mr. Charles S. Tomes in _Nature_, of 12 June, 1879 (which has been made use of in the present description), and there is also a letter about the accident by Mr. Newall on the next page of _Nature_ to Mr. Tomes’ letter. The description in this latter letter is, however, erroneous in several particulars, especially where it speaks of the lightning passing round the iron gutters to the iron water cisterns.

ROGERS FIELD, _B.A. Lond., M. Inst. C. E., F.M.S._

CANNON ROW, WESTMINSTER.

[NOTE.—Mr. Tomes has most kindly sent the whole of the upper parts of the conductor; and as the accident appears a very instructive one we give full details, together with engravings of the more important portions of the conductor.—ED.]

This conductor was of the pattern known as Spratt’s patent. The upper terminal was what the vendors call a “reproducing point,” which they say is “formed of two or more metals: the inner or core being steel, and the outer of silver alloy, tipped with platinum;” the idea of the inventor is said to have been that “should the outer coating become fused by an extraordinary charge of electricity, the core will remain intact to receive any further discharge.” In the present case the top is broken and the iron centre is rusted and bent, but there is no indication on the remaining portion of heat or fusion.

This point A was well screwed into a stout copper collar B.

Into the same collar was screwed the upper end of a copper tube C, 5 ft. 1 in. long, external diameter, 0·5 in., and internal diameter about 0·36 in., giving a thickness of only 0·07 in., or but little more than a sixteenth of an inch. The mass of copper was therefore about equal to a tape 1½ × 1/16, or ¾ × ⅛, or to a rod one-third of an inch in diameter—the area being as nearly as possible 0·09 in. The tube weighs 29½ ounces, which corroborates the above measurements and shows that it weighs rather less than 6 ounces per foot. This part of the conductor was evidently greatly heated, as there are distinct marks of sweating in several places. The lower part of this tube was screwed into the collar D (which is drawn of its actual size in the annexed sketch) in order to make connection with the short length of copper tube F, a portion of which is also engraved, of its actual size. It was at E that the rupture occurred. The charge passed the point A, then the top collar B, and although it greatly heated the 5 ft. copper tube C, still no damage was done, and so it passed into the second collar. Here, however, there seem to have been two faults: the short copper tube F, was very slight, weighing but little over 3½ ozs. to the foot, and this, which represents but a very slight conductor, was greatly lessened by a deeply-cut thread to the upper end, whereby the area was reduced to less than 1/20th of an inch. As this was not screwed home, the total sectional area at E immediately below the collar was reduced to the above small amount, rupture and fusion occurred, and much of the charge left the conductor. This short length of tube was, however, raised to a sweating temperature in two places.

The conductor consisted of 14 wires made into a flat plait, the wires seem to have been of the following dimensions:—

Each of No. Total area. 12 copper wires, 15 B.W.G., dia. of each ·072 in.: 0·048 in. 1 copper wire, 18 B.W.G., dia. of each ·049 in.: 0·001 in. 1 zinc wire, of each ·049 in.: 0·001 in.

Thus the total sectional area of the plait G would be about 0·050 in., or rather more than that of the short copper tube into the lower end of which it was roughly thrust and riveted—but the joint was bad, there was no solder at all, and the metallic contact was very imperfect.

As to the state of this plait (which was less than an inch wide, and less than ⅒ in. thick), and as to the ridiculously imperfect earth terminal, details are given in Mr. Field’s letter.

It may be well to recapitulate the dimensions:—

┌─────────────┬─────────────┬─────────────┬─────────────┬─────────────┐ │DESCRIPTION. │ LENGTH. │ DIMENSIONS. │ SECTIONAL │HEAT EFFECTS.│ │ │ │ │ AREA. │ │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │“Reproducing │ 9 in. │0·45 × 0·45 │ 0·20 │None visible.│ │ point” │ │ in. │ │ │ │Collar │ 1¼ in. │0·75 in. │ 0·24 │None visible.│ │ │ │ diam. │ │ │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │ │ │External 0·5 │ │ │ │ │ │ in. dia. │ │{Sweated in │ │Copper tube │ 5 ft. 1 in. │ Internal │ 0·09 │ places. │ │ │ │ 0·36 in. │ │ │ │ │ │ dia. } │ │ │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │ │ │External 0·75│ │ │ │ │ │ in. dia. │ │ │ │Collar │ 1⅛ in. │ Internal │ 0·24 │None visible.│ │ │ │ 0·50 in. │ │ │ │ │ │ dia. │ │ │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │ │ │External 0·50│ │ │ │ │ │ in. dia. │ │{Sweated in │ │Short tube │ 7 in. │ Internal │ 0·09 │ places. │ │ │ │ 0·375 in. │ │ │ │ │ │ dia. │ │ │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │ │ │External │ │ │ │Short tube │ │ 0·438 in. │ │ │ │ where │ ¾ in. │ dia. │ 0·04 │Fused. │ │ threaded │ │ Internal │ │ │ │ │ │ 0·375 in. │ │ │ │ │ │ dia. │ │ │ ├─────────────┼─────────────┼─────────────┼─────────────┼─────────────┤ │Plait │ 53 ft. │? 0·7 × 0·072│ 0·05 │Sweated in │ │ │ │ in. │ │ places. │ └─────────────┴─────────────┴─────────────┴─────────────┴─────────────┘

G. J. S.

* * * * *

We herewith hand you our circular, setting forth our ideas as to lightning conductors. We claim that if one or more sharp edges or points is so essential on the most elevated part or parts of a conductor, why not establish this principle the entire length of the conductor? or why not leave these most elevated part or parts blunt, or erect a small gilt ball?

DAVID MUNSON & Co.

INDIANAPOLIS, INDIANA, U.S.A.

[The engravings are not drawn to scale, but are here reproduced; the shaded parts are galvanized iron, the lighter parts copper.—ED.]

* * * * *

I think that it would be very valuable if the Conference considered how far iron ventilating pipes to drains will safely act as lightning conductors. These pipes generally consist of iron jointed with red lead or putty. Will not these joints interfere? Very often also a portion of the pipe is wholly of lead. So many of these pipes are now carried up to a very high level that the question is important.

ROGERS FIELD, M.Inst.C.E.

CANNON ROW, S.W.

* * * * *

Our opinion is that the drain to our Powder Magazine at Bruntcliffe (see ante page 74) had no water in it at the time of the occurrence.

JOHN HAIGH & SONS.

VICTORIA COLLIERIES, GILDERSOME.

* * * * *

We have the pleasure to send you a plated model of our new Conductor Coupling, and hope you will be pleased with it.

When screwed up, the contact between the rod and the copper tape is perfect. It is, of course, a very simple thing, but it overcomes the difficulty of soldering, which is always more or less uncertain, and rivetting up aloft is apt to be scamped.

And as to soldered connections, apart from the uncertainty of permanent contact, it is very important to keep the soldering iron away from roofs, it often damages the lead, and (as at Canterbury) the fire-pot is a source of great danger to buildings.

A is the copper tape conductor. B is a screw plug, having two slots, _a a_ (see fig. 3), and an intervening division _b_, all cast in one piece. The tape or rope A is passed through one of the slots _a_, and bent over the division piece _b_, the bent portion A1 is then returned through the other slot. A screw socket forming the coupling C, bearing a collar to rest in a ring bolt built into the structure to be protected, is then screwed on to the plug B, and into this socket the rod or tube D is screwed, it being suitably tapped for its reception, until the lower end of the rod or tube is in firm contact with the tape or rope. These latter are then firmly held together, and cannot by any possibility come apart.

NOTE.—In fig. 2 the rod and tape are not shown in actual contact, the drawing being intended to exhibit the separate parts.

R. C. CUTTING & Co.

147, QUEEN VICTORIA STREET.

* * * * *

I have the pleasure of furnishing details of the recent damage to Christ Church, at Carmarthen. The circumstances are these:

At the Eastern end of the church stands an ordinary square tower, covered with a sloping slated roof; this roof is capped by an ornamental open ironwork ridging, terminating at each end in a light open iron pinnacle, and having in the centre another pinnacle similar to those at the extremities. A is a view of this ironwork from the east end of the church.

The conductor consisted of seven copper ropes stranded together, each rope consisting of seven strands of No. 18 wire, the whole having a diameter of about ½ an inch. It was fixed to the building by ordinary copper staples; it ran up, and was attached to the southern portion of the ornamental railing, and it terminated in a single point. There was no special connection between the conductor and the iron guttering of the church.

I could not ascertain in what manner the earth was made, but it was an imperfect one, giving a resistance of 115 ohms, and this resistance would have been greater but for an accidental circumstance mentioned further on.

The lightning struck the central iron pinnacle of the ornamental ridge and broke it off. In falling to the ground it was shattered into about twenty pieces; but on the upper extremity, which was a solid cast-iron spike, about ¾ inch square, there were marks of fusion across the whole of the top to the depth of ⅛th of an inch.

I could not observe other marks of fusion at the point where the pinnacle was broken off, but the lightning made its way to the conductor, and on reaching the ground, at a distance of 4 feet from the point where it entered, it burst out with explosive violence, blowing a circular hole in the ground 2 feet in diameter and 8 inches deep (marked B in plan). The earth from this hole was blown into the air, and fell in a fine shower on objects standing 3 or 4 feet high and 14 or 15 feet from the hole.

A second flash struck the iron guttering at the south-western extremity of the church (C), broke off a 2 feet length, and ran down the waterspouts (D D). Opposite one of these a second hole, 9 inches deep and a foot in diameter, was blown out of the ground, some 3 feet from the base of the spout.

On examining more closely the surroundings of the lightning conductor, I observed that the church gas-pipe, an iron one, about 1¼ inches in diameter, passed through the wall of the building about 6 feet from the conductor, and was carried in a direction corresponding with the hole caused by the explosion (see plan). I immediately concluded that this explosion was due to the current breaking across from the conductor to the gas-pipe, and on opening up the hole I found this to be the fact. The conductor crossed the gas-pipe at nearly a right angle, being about a foot above it. The under portion of the conductor bore evident marks of fusion, and, more interesting still, the gas-pipe was slightly coated with a very thin deposit of copper, so thin that it perished in my attempt to remove it; but still there was an undoubted coating at one spot. But for the proximity of the conductor to the gas-pipe, the earth resistance of the former would doubtless have been greater than it was, and the damage would probably have been increased.

I was sorry that no means existed for examining the ornamental ridge, but doubtless the metallic contact between the sections was very imperfect, and to this cause was due the rupture of the pinnacle.

The fact, too, that the protector did not prevent the south-western portion of the building being struck bears on the question of the area made safe by a protector.

The tower stood 89 feet above the ground, the top of the iron pinnacle 99 feet, and the protector extended 1 foot 6 inches above the latter, thus reaching a total height of 100 feet 6 inches. The total length of the church was 123 feet.

The point C where the gutter was struck was 84 feet in a direct line from the conductor, and stood 24 feet above the ground. This gives a vertical height of the conductor of 76 feet 6 inches above the point struck, the distance of the latter being a radius 8 feet greater than the height of the former.

J. GAVEY.

CARDIFF, _January 10th, 1880_.

ACCIDENT AT BOOTHAM BAR, YORK, COMPILED FROM NOTES AND MEASUREMENTS TAKEN BY J. EDMUND CLARK.

The discharge occurred about 3 a.m., 22nd June, 1876. The principal injury occurred to the bracket lamp at A. This lamp, which was an ordinary street one, was supported by an iron bracket 2 ft. 6 in. long, and 11 ft. 6 in. above the pavement. The gas was conveyed to it by 11 ft. 6 in. of vertical iron gas barrel, and thence to the burner by about 3 ft. of ordinary ½ in. composition pipe. The glass of the lamp was not broken, but about 18 inches of the composition piping was twisted and split open as with a sharp knife, and the other 18 inches was melted; the gas was ignited and burning from the top of the iron barrel, thus producing a large flame which ignited the house to which it was fixed. That part of the lead pipe which was inside the lamp was uninjured, whence it would appear that the point struck was at or near to the top of the iron gas barrel; and this is supported by the fact that the lead over the shop window and close to the bracket was turned up off the wood-work.

The lamp, as will be seen by the plan, is attached to the corner of a house, the eaves of which were 20 ft. above the lamp, while the ridge, with a little lead flashing, was 24 ft., and the chimney pots were 31 ft. above the lamp, and not 15 ft. distant horizontally. This house was slated and had wood gutters, and an iron rain-water pipe, but the latter was 33 ft. horizontally from the point struck. The wooden gutters were very old and rotten, and one of them was very slightly shifted; it is not certain that this was done by the lightning, and there was no other indication of its presence.

C is a lamp bracket extending 4 ft. from the wall of the house, and at D are two old iron brackets.

At the distance of only 8 ft. from the lamp in the opposite direction (N.W. of the lamp) rises Bootham Bar, a massive stone structure, of which the four turrets rise to 44 ft. 3 in. above the pavement, and therefore 33 ft. above the lamp. The whole roof, about 750 square feet, is covered with thick sheet lead, and the building also contains the old portcullis B heavily shod with iron.

The noteworthy feature of the case appears to be, that the only injury is found at a spot surrounded by objects close to it, and greatly exceeding it in height; in fact, that the lightning dipped into a sort of cavity, instead of striking at the higher objects.

It is evident that in this case, although the composition pipe was melted, the _iron_ one afforded ample conduction, and the city gas mains a perfectly safe earth terminal.

ACCIDENT AT BOOTHAM BAR, YORK.

REFERENCES.

A Gas bracket struck. B Iron sheathed portcullis. C Old gas bracket. D Old Iron brackets.

APPENDIX J.

DATA RESPECTING THE SECTIONAL AREA OF METAL REQUISITE FOR LIGHTNING CONDUCTORS.

(N.B.—In order to avoid confusion, all areas of iron have been reduced to ⅙th of their actual sizes, so that virtually tables I. and II. may be regarded as giving all details for _copper_—but the metal is specified in each case.)

TABLE I.—LIST OF METALS MELTED.

───────────────────┬────┬─────────────────┬──────────────────────────── Material │Form│ Size │ REMARKS ───────────────────┼────┼─────────┬───────┼──────────────────────────── │ │Diameter.│Area of│ │ │ │Copper.│ ───────────────────┼────┼─────────┼───────┼──────────────────────────── │ │ in. │ in. │ COPPER │Rod │·35 │·10 │Duprez, App., p. 92 COPPER │Rope│·31 │·075 │At Nantes, Callaud’s │ │ │ │ _Traité_, p. 89 [6]_Not Specified._│Rope│ │·07 │At Carcassone, Callaud’s │ │ │ │ _Traité_, p. 89 IRON │Rod │ │·03 │Harris on Thunderstorms, p. │ │ │ │ 109 BRASS │Rod │·20 │·03 │Duprez, App., p. 92 COPPER │Rod │·13? │·01? │Sullivan, App., p. 195 ───────────────────┴────┴─────────┴───────┴────────────────────────────

Footnote 6:

Assumed to have been Iron, the dimension given is “18 mm.” = ·70 in. diam., or ·38 in. area.

TABLE II.—REMARKS RESPECTING DIMENSIONS.

───────────────────┬────┬─────────────────┬──────────────────────────── Material │Form│ Size │ REMARKS ───────────────────┼────┼─────────┬───────┼──────────────────────────── │ │Diameter │Area of│ │ │ │Copper.│ ───────────────────┼────┼─────────┼───────┼──────────────────────────── │ │ in. │ in. │ COPPER │Rod │ │·61 │Trinity House smallest, │ │ │ │ App., p. 183 COPPER │Rod │·75 │·44 │Will carry any flash, Harris │ │ │ │ on _Thunderstorms_, p. 115 COPPER │Rod │·50 │·20 │Never yet failed, Faraday, │ │ │ │ App., p. 89 COPPER │Tube│ │·20 │War Office smallest, App., │ │ │ │ p. 70 COPPER │Tape│ │·19 │Gray & Son’s smallest, App., │ │ │ │ p. IRON │Rod │ │·16 │Never affected, Franklin, │ │ │ │ App., p. 52 COPPER │Any │ │·11 │Recommended by Phin, App., │form│ │ │ p. 103 IRON │Rod │ │·11 │More than sufficient, Gay │ │ │ │ Lussac, App., p. 58 COPPER │Rope│·38 │·11 │Recommended by Callaud, │ │ │ │ App., p. 104 COPPER │Tape│ │·09 │Freeman & Collier’s │ │ │ │ smallest, App., p. 10 IRON │Rod │ │·08 │Never known to be melted, │ │ │ │ Pouillet, App., p. 62 IRON │Rod │ │·08 │Should not be less, Henry, │ │ │ │ App., p. 99 COPPER │Rope│·39 │·06 │Carried off heavy discharge, │ │ │ │ Callaud _Traité_, p. 89 IRON │Rod │ │·06 │Recommended by Callaud, │ │ │ │ App., p. 104 IRON │Rod │ │·06 │Recommended by Mohn, App., │ │ │ │ p. 107 COPPER │Rod │·25 │·05 │Recommended by Mohn, App., │ │ │ │ p. 107 IRON │Rod │ │·04 │Recommended by Phin, App., │ │ │ │ p. 103 COPPER │Rod │·20 │·03 │Recommended by Zenger, App., │ │ │ │ p. 106 IRON │Rope│ │·02 │Recommended by Mann, App., │ │ │ │ p. 108 IRON │Wire│ │·01 │Sufficient for any house, │ │ │ │ Preece, App., p. 101 ───────────────────┴────┴─────────┴───────┴────────────────────────────

DIMENSIONS OF LIGHTNING RODS—COPPER.

_Partly extracted from the Appendix at the pages quoted, and partly compiled from specimens collected by the Conference, and from trade circulars._

────────────┬────────┬───────┬─────────┬───────────┬────┬──────┬──────────── │ │ │ │ │ │Weight│Remarks, and Pattern │Diameter│Breadth│Thickness│Superficies│Area│ per │ References │ │ │ │ │ │ foot │ to │ │ │ │ │ │ │Appendices. ────────────┼────────┼───────┼─────────┼───────────┼────┼──────┼──────────── │ Inches │Inches │ Inch │ Inches │Inch│ oz. │ │ │ │ │ │ │ │ │Ext. 1½ │ │ │ Ext. 4·71 │ │ │Sir W. Snow TUBE │ Int. 1 │ │ ¼ │ Int. 3·14 │ ·98│ 60│ Harris │ │ │ │ │ │ │ (49) │ │ │ │ │ │ │ │ │ │ │ │ │ │Trinity HEMICYLINDER│ 1½ │ │ │ 3·86 │ ·88│ 54│ House, │ │ │ │ │ │ │ Mains │ │ │ │ │ │ │ (183) │ │ │ │ │ │ │ │ │ │ │ │ │ │Trinity HEMICYLINDER│ 1¼ │ │ │ 3·21 │ ·61│ 37│ House, │ │ │ │ │ │ │ Branches │ │ │ │ │ │ │ (183) │ │ │ │ │ │ │ │ │ │ │ │ │ │Freeman & TAPE │ │ 3 │ 3/16 │ 6·38 │ ·56│ 34│ Collier’s │ │ │ │ │ │ │ largest │ │ │ │ │ │ │ (10) │ │ │ │ │ │ │ TUBE │Ext. 1½ │ │ ⅛ │ Ext. 4·71 │ ·54│ 33│ │Int. 1¼ │ │ │ Int. 3·93 │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │Faraday │ │ │ │ │ │ │ preferred ROD │ ¾ │ │ │ 2·35 │ ·44│ 27│ this to │ │ │ │ │ │ │ smaller │ │ │ │ │ │ │ (89) │ │ │ │ │ │ │ │ │ │ │ │ │ │Gray & Son’s TAPE │ │ 3 │ ⅛ │ 6·25 │ ·37│ 23│ largest │ │ │ │ │ │ │ (7) │ │ │ │ │ │ │ TUBE │ Ext. 1 │ │ ⅛ │ Ext. 3·14 │ ·34│ 21│ │ Int. ¾ │ │ │ Int. 2·36 │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │Sanderson’s TAPE │ │ 2 │ ⅛ │ 4·25 │ ·25│ 15│ largest │ │ │ │ │ │ │ (23) │ │ │ │ │ │ │ TAPE │ │ 1½ │ ·15 │ 3·30 │ ·23│ 14│ │ │ │ │ │ │ │ │ │ │ │ │ │ │War Office │ │ │ │ │ │ │ (70) ROD │ ½ │ │ │ 1·57 │ ·20│ 12│ Sir W. │ │ │ │ │ │ │ Snow │ │ │ │ │ │ │ Harris │ │ │ │ │ │ │ (49) │ │ │ │ │ │ │ │ │ │ │ │ │ │War Office │ │ │ │ │ │ │ (70) TAPE │ │ 1½ │ ⅛ │ 3·25 │ ·19│ 12│ “Smallest │ │ │ │ │ │ │ desirable” │ │ │ │ │ │ │ Gray & Son │ │ │ │ │ │ │ (7) │ │ │ │ │ │ │ TUBE │ Ext. ⅝ │ │ ⅛ │ Ext. 1·96 │ ·20│ 12│War Office │ Int. ⅜ │ │ │ Int. 1·18 │ │ │ (70) │ │ │ │ │ │ │ TAPE │ │ 2½ │ 1/16 │ 5·12 │ ·15│ 9│J. Davis & │ │ │ │ │ │ │ Son (14) │ │ │ │ │ │ │ ROPE (49 │ │ │ │ │ │ │Pennycook & square │ ⅔ │ │ │ 10·78 │ ·15│ 9│ Co. wires) │ │ │ │ │ │ │ │ │ │ │ │ │ │ TAPE │ │ 2 │ 1/16 │ 4·12 │ ·13│ 8│ │ │ │ │ │ │ │ TAPE │ │ 1 │ ⅛ │ 2·25 │ ·13│ 8│Phin, of New │ │ │ │ │ │ │ York (103) │ │ │ │ │ │ │ │ │ │ │ │ │ │{Massingham ROPE (49 │ ½ │ │ │ 8·00? │ ·10│ 6│ (15) wires) │ │ │ │ │ │ │ Newall’s │ │ │ │ │ │ │ Rope │ │ │ │ │ │ │ TAPE │ │ 1½ │ 1/16 │ 3·12 │ ·09│ 6│ │ │ │ │ │ │ │ │ │ │ │ │ │ │Freeman & TAPE │ │ ¾ │ ⅛ │ 1·75 │ ·09│ 6│ Collier’s │ │ │ │ │ │ │ smallest │ │ │ │ │ │ │ (10) │ │ │ │ │ │ │ │ Ext. ⅞ │ │ │ Ext. 2·75 │ │ │ TUBE │ Int. │ │ 1/32 │ Int. 2·55 │ ·08│ 5│ │ 13/16 │ │ │ │ │ │ │ │ │ │ │ │ │ ROPE (36 │ │ │ │ │ │ │ wires & │ 7/16 │ │ │ 5·00? │ ·08│ 5│J. Davis & hemp │ │ │ │ │ │ │ Son (14) centre) │ │ │ │ │ │ │ │ │ │ │ │ │ │ SPRATT’S │ │ │ │ │ │ │ PATENT │ │ 1⅓ │ │ 4·52 │ ·08│ 5│ PLAIT (20 │ │ │ │ │ │ │ wires) │ │ │ │ │ │ │ │ │ │ │ │ │ │ TAPE │ │ 1 │ 1/16 │ 2·12 │ ·06│ 4│ │ │ │ │ │ │ │ ROPE (49 │ ⅜ │ │ │ 6·00? │ ·06│ 4│Newall’s wires) │ │ │ │ │ │ │ Rope │ │ │ │ │ │ │ │ │ │ │ │ │ │Sanderson’s TAPE │ │ ⅝ │ 1/12 │ 1·42 │ ·05│ 3│ smallest │ │ │ │ │ │ │ (23) │ │ │ │ │ │ │ SPRATT’S │ │ │ │ │ │ │ PATENT │ │ 1 │ │ 3·16 │ ·05│ 3│ PLAIT (14 │ │ │ │ │ │ │ wires) │ │ │ │ │ │ │ │ │ │ │ │ │ │ HART’S PLAIT│ │ │ │ │ │ │ (13 copper│ │ │ │ │ │ │ wires and │ │ │ │ 3·08 │ ·05│ 3│ 1 zinc │ │ │ │ │ │ │ one) │ │ │ │ │ │ │ ────────────┴────────┴───────┴─────────┴───────────┴────┴──────┴────────────

APPENDIX K.

NOTES RESPECTING LIGHTNING CONDUCTORS, COLLECTED IN PARIS IN MAY, 1881, BY MESSRS. PREECE & SYMONS.

The information which we obtained may perhaps be most conveniently grouped under the names, arranged in alphabetical order, of the authorities whose opinions or whose practice we quote. These gentlemen are M. Androuët, who, under the direction of M. Alphand, the City Engineer, has charge of all the lightning conductors attached to the municipal buildings of Paris, M. Borrel, of 47, rue des Petits Champs, who has been making lightning conductors nearly all his life, M. le Comte du Moncel, who is well known as perhaps the highest authority in France upon the practical application of electricity, and lastly M. Jarriant who is manufacturer to the municipality, and also, we believe, to the War Department, besides having a large connection among architects and engineers.

* * * * *

M. ANDROUËT accompanied us in a thorough examination of the conductors as they are now fixed upon the south gallery of the Louvre, temporarily occupied as the Hotel de Ville de Paris. They were stated to be only temporarily fixed, because the offices of the Préfet of the Seine will be removed to the new Hotel de Ville as soon as it is rebuilt, but they were said nevertheless to be in almost all respects conformable to the instructions issued by the municipality. The _tiges_ were iron rods, 10 m. (33 feet) high, with rather blunt terminals of gilded copper; they were 35 m. (115 ft.) apart. All were united by a horizontal copper rope, ½ inch diameter (used instead of iron bars 0·8 in. square, because of the temporary nature of the work), which was led along the roof through iron holdfasts or crutches, which were carefully soldered to the metal roof. All joints in the rope were spliced and heavily soldered. For æsthetic reasons the main conductor is carried down _inside_ the building, through various closets, &c., and finally, after a rather circuitous course, it finds its earth terminal in a plate of copper 1 m. (3 ft. 3 in.) square, immersed in the Seine. Although the roof is well covered with metal no separate connections with earth are made. M. Androuët tests the conductivity from every _tige_ in the spring of each year, using a very portable apparatus, consisting of two Leclanché’s cells and a trembling bell.

* * * * *

M. BORREL showed us various specimens of conductors, of earth terminals, and also his portable testing apparatus. He also gave us a copy of the _Instruction sur les Paratonnerres_, which he issues, and from which we make a few extracts, especially as in several respects M. Borrel’s views are expressed with unusual clearness, and although in holding some of them he stands alone:

“A lightning conductor is a preventive agent destined to convey to moist earth, or preferably to water, the electricity contained in a cloud. When strong earth tension is produced by the passage of an oppositely electrified cloud, the beneficial action of the conductor is indicated by the luminous brush discharge from the top of the conductor.

“It is generally considered that a conductor protects a cone of revolution, having for its base the height of the point above the roof multiplied by 1·75, and for its summit the point. If, therefore, the point be 6 m. (20 ft.) above the roof, it will protect a base 10½ m. (35 ft.) radius. M. Borrel supplies round upper terminals of galvanised wrought iron about 10 m. (33 ft. high), and tapering from a diameter of 4 inches at the base to ¾ inch at the top.

“Having found that long exposure to the weather destroys iron wire ropes, and even copper ones, if made of many small wires, he has adopted where ropes are necessary, four or five rods nearly 0·20 in. diameter, so slightly twisted as not to strain the metal. By this means the numerous interstices of the ordinary ropes are avoided, and much greater durability is insured.

“Where iron bars are used he employs galvanised wrought iron in square bars, the sides ranging from 0·63 in. to 0·90 in.

“To allow for variations of length produced by changes of temperature, he always inserts, in long roof conductors, a compensator, which is merely a loop of copper tape.

“M. Borrel says that it is especially upon the earth connection that the efficacy of a conductor largely depends; there must be a metallic mass, with a large surface, and he describes his pattern of ‘_perd fluide_.’ It is composed of two sheets of galvanised wrought iron 3 ft. long, 6½ in. wide, and ½ an inch thick, hacked into sharp points in order to facilitate the discharge of the electricity. He alludes to Callaud’s basket of coke, but says that its efficiency has not been absolutely demonstrated. M. Borrel insists upon the _perd fluide_ being immersed in the water of a well, and one preferably not less than 2 ft. in diameter. He strongly objects to insulators, and says that he always makes metallic connection between the gutters, rain-water pipes, &c. and his conductors. From the surface of the earth to 6 ft. above it, he encloses his conductor in a wooden case in order that no one may touch it during a storm.”

* * * * *

We had a long conversation with M. LE COMTE DU MONCEL, of whose remarks the following is a _précis_:—

He objects to _square_ iron bars because their angles have a tendency to facilitate lateral discharge.

He objects to conductors being painted, because he believes that the surface of a conductor acts electro-statically. He knows that the brass wire rope occasionally used for lighthouses is often destroyed, but thinks that the theory enunciated in the Report of the Académie des Sciences, 18th December, 1854 (see Appendix F., p. 62), can hardly be maintained, and believes it to be more probable that the rope was in a very bad state of oxidation.

Thinks that conductors should possess _both_ sectional area and surface. Does not attach much importance to extremely sharp points, but thinks that the suggestion of one stout central one to receive a disruptive discharge, surrounded by three or four needles to facilitate silent discharge, would be good.

The following statement was quoted from the Report of 20th May, 1875 (see Appendix F., page 68), that, “if a conductor cannot be led either to the subterranean water or to a main water-pipe, no lightning rod should be erected. It would do more harm than good.” Count du Moncel said that the paragraph referred chiefly to buildings on large solid rocks, but that obviously there is every degree of quality in the earth contact which can be obtained; and that although it is easy to decide at the two extremes, it is difficult to say how bad the earth must be in order to render the erection of a conductor inadvisable.

* * * * *

M. JARRIANT, who is the manufacturer employed upon the Municipal buildings of Paris (and author of two pamphlets, of which abstracts are given in Appendix F, pages (111) and (115)), accompanied us through his works, and afforded us all the information which we could desire.

He showed us a large collection of platinum points of various patterns, ranging in cost from 12s. to 60s. each; he also showed us some which had been employed by other makers, which were merely hollow sheaths of platinum filled in with soft metal in order to reduce the cost.

He had also a large variety of upper terminals, including the patterns used by the City of Paris, by the War Department for its military establishments, and by civil engineers and architects.

We saw specimens of the ropes, rods, &c., usually supplied. The iron ropes were galvanized and ¾ in. diameter. The copper ropes were made of six twisted strands of copper wire enclosing a central core of hemp, the total diameter being ½ an inch. The iron bars were square galvanized wrought iron 0·80 in. square, in lengths of 16½ feet, rabbetted at the ends with two holes for bolts. To make a joint a strip of foil is laid between the two faces, the bolts are screwed up, and then the whole joint is very heavily soldered.

Among various works in progress, we saw a highly decorated wrought iron cross for the roof of a church, which cross would become the summit of the conductor, its top and the extremity of each arm being furnished with a short copper terminal tipped with a platinum point.

We were much struck by the fact that in France, where so much attention has been given to lightning protection, there should be so much diversity of practice. The Municipality adopt one system, the State another, the War Department a third, and each individual manufacturer has, as in England, his hobby.

We desire to record our thanks to Mr. J. Aylmer, C.E., for making the various arrangements, by which we were able to see so much in the comparatively short time at our disposal, and also for accompanying us throughout.

W. H. PREECE.

G. J. SYMONS.

P.S.—A very convenient form of a rough testing apparatus has been made, by the Silvertown Co., for one of the writers; it consists of one Leclanché cell, a trembling bell, a key, and a pair of terminals to attach insulated wires to the top and bottom of the lightning rod, all fixed in a neat portable mahogany box, and with its aid any one can readily examine the conductivity of his lightning rod.

APPENDIX L.

ON THE LIGHTNING CONDUCTORS AT THE PARIS INTERNATIONAL ELECTRICAL EXHIBITION, BY MESSRS. DYMOND AND SYMONS.

It was hoped that at the Paris Electrical Exhibition would be found examples of the various styles and patterns of lightning rods used in the several countries of Europe and in the United States, and we accordingly visited the Exhibition and inspected all the exhibits in any way relating to the subject.

Those from France were naturally the most numerous (15), but there were some very elaborate specimens of the system adopted in Belgium, in accordance with the recommendations of M. Melsens; and there was also sent by Dr. Weber, of Kiel, a very interesting collection of 12 points which had been struck by lightning, all more or less fused and damaged.

The French exhibitors showed a great variety of points, but they were for the most part referable to two or three types or classes, and only varied in size. The favourite form appeared to be that shown by Fig. 1, a rather finely tapering brass rod terminated by an acornshaped piece, from the upper end of which projected a small needle. They were constructed to be screwed to the top of the iron _tige_. They varied in size from 1 ft. long and ¾ in. diameter at the base, tapering to ¼ in. at the acorn, to 2 ft. 6 in. long and 1¼ in. diameter, tapering to ¼ in. The acorns were generally about twice the diameter of the point to which they were joined, and were about 1½ diameter long. The needles were always made of platinum about 1½ in. long and ·1 in. diameter. Some exhibitors showed a very similar pattern, but made in copper instead of brass. There were also several specimens of blunt points in copper—the _Point Municipal_, Fig. 2, tapering from 1 in. to ½ in. diameter and 1 ft. 8 in. long; tapering brass and iron rods, some of them having platinum cones, were also exhibited. All these points were intended to be mounted on exceedingly long upper terminals.

The conductors were generally made of wire rope, copper, brass, or galvanized iron, and in the majority of cases composed of strands of small wires, though there were a few specimens of ropes made of large wires (say) ·1 in. in diameter; and there were also some specimens of conductors made of iron bars with copper expansion bands. These last specimens were about ·8 in. square, but almost all the ropes seemed to us too small, generally about ·4 in. diameter, and we were surprised to see that the iron ropes were no larger than the copper or brass ones.

The methods adopted for joining them to the upper terminals were either to push the end into a socket and pin them across, or more frequently to tie them more or less loosely round the base.

The practice as to insulation seemed to vary, some makers supplying insulators and others not, but they almost all provided for carrying the conductor from 6 to 9 in. away from the face of the building.

There were but few specimens of earth plates, they were in the form of grapnels, and seemed very inadequate; not one would afford 3 superficial feet of earth contact.

Some models and drawings showed that the French electricians assumed a cone of protection whose radius was at least 1·75 of its height. (See ante page (67).)

Excepting France the most numerous series of exhibits was that from Belgium, which also contained a complete model of the monument erected at Lacken in memory of Leopold I., showing the manner in which it had been fitted with conductors under the superintendence, or according to the system, of M. Melsens.

The monument referred to is a ten-sided Gothic building, with pinnacles on two storeys and a spire. On the top of the spire, but below the figure, is a considerable number of radiating points, and there is a similar frill round the top of each of twenty pinnacles. Each aigrette consists of seven copper points, each about 0·4 in. in diameter and 2 ft. long, tapering to a very sharp point; they are all leaded into a collar or band encircling the stone work; and from them go the rods about 0·4 in. in diameter, which are first taken into a cast iron box about 8 in. × 5 in. × 2 in.; into this box are also taken rods which lead to connections with (1) a well, (2) the water mains, and (3) the gas mains. When these two series of rods are all in position in the box it is filled with melted lead, and thus perfect connection is secured. There were specimens of the aigrette, and also of the manner of joining the rod to the gas and the water mains, and to the large iron pipe which is sunk in the well. This is effected by bringing all the rods parallel with the main, and arranging them, at equal distances from each other, around it. They are then held tightly to it by two semicircular clamps bolted together, and melted lead is poured in and caulked. The main, and probably the inside of the clamps, was filed bright when the joint was made.

The other exhibits—patterns of points and conductors—do not call for any special mention, but we may notice that the Belgian makers were generally much more careful than the French to make good electric contact at the joints, and some conductors were exhibited cut through the joints to show the care bestowed in this particular.

From Germany were sent some specimens of wire rope for conductors, made of the usual strands of small wires. The iron ropes were slightly larger and of slightly larger wires than the copper, but the former were not more than 0·6 in. in diameter.

* * * * *

Dr. WEBER, of Kiel, exhibited a collection of 12 points, all which have been struck by lightning—their length varies from 4 in. to 7 in., they are of gilded copper, about 1 in. in diameter at the thickest point, and vary in the acuteness of their extremities—some have platinum needles, about 0·08 in. diameter, screwed into their points; these needles have, in most cases, been wholly fused. In some cases the platinum is somewhat thimble-shaped, and fitted over the copper—in these cases the platinum is generally wholly melted, and the copper uninjured. Platinum of 0·12 in. diameter has been melted, but there is not one of these points of which copper of that size has been fused. There is no indication that these points have been fixed to tiges—on the contrary, they are all hollow at the base, and have had soldered into them copper ropes, none exceeding 0·33 in. diameter, and most of them consisting of three strands of six wires each (=18 wires), the wires being about No. 18 B.W.G.

There were a few specimens of gilded copper points, sent from Austria, such as Fig. 3; and our English makers also sent a few examples of points, the crow foot, Fig. 4, for instance, of upper terminals, and of rope and tape conductors.

E. E. DYMOND.

G. J. SYMONS.

APPENDIX M.

MISCELLANEOUS.

MEANS TO BE ADOPTED FOR ENSURING PERSONAL SAFETY FROM THE EFFECTS OF LIGHTNING.

(_Abstracted by Prof. G. Carey Foster, F.R.S._)

WORKS CONSULTED:—

│Received from the _Correspondence_ addressed to Lightning Rod │ Secretary of Conference. │ Lightning Rod │ Conference. Directions for Insuring Personal Safety during │ Storms of Thunder and Lightning; and for * * * │ By _John Leigh_, pp. 60. London (no date). │

_Benjamin Franklin._ Complete Works. 3 vols. 8vo. London, 1806.

_Gehler._ Physikalisches Wörterbuch. Article “_Blitz_,” Leipzig, 1825.

_François Arago._ Meteorological Essays, from the French by Sabine. London, 1855.

_C. Kuhn._ Handb. d. angewandten Elektricitätslehre. Leipzig, 1866.

The danger to men and animals from the effects of lightning arises from the fact that the bodies of living animals form comparatively good conductors of electricity,—better, that is, than rain-water (probably better even than sea-water), or than trees, walls of brick or stone, hay-stacks, or in fact than almost any common objects consisting of non-metallic materials. It may be assumed that the path of a lightning-discharge striking the earth is determined by the line of least inductive resistance between the thunder-cloud and the earth.[7] Hence, a man standing on an open plain, or walking, or riding on horseback, or in an open vehicle, across it, is liable to be struck by lightning. There is no evidence that the motion of walking or riding makes the liability either greater or less than it would be if he were at rest. The danger is increased, other conditions being the same, by nearness to water, or to large masses of metal, or other conducting material, lying flat on the ground or rising only a little way from it. An umbrella held over-head is probably dangerous, but I do not find direct evidence that it is so among recorded cases.[8] Such small metallic articles—money, keys, &c.,—as may be commonly carried in the pocket, have probably no perceptible effect. In the open country, beyond the reach of shelter, low-lying positions, if dry, are safer than those which are more elevated and exposed; but, on the other hand, water-courses are to be avoided. It is also safer to lie flat on the ground than to stand or sit. If shelter is within reach, care should be taken to get _completely under cover_. There is often much more danger in standing under the lee of a house, or wall, or hay-stack, or thicket of trees, than in remaining quite exposed. There is but little danger, however, _inside_ a barn or outhouse, as far as possible from the walls, or _underneath_ a wagon or the arch of a bridge. The inside of a wood is also a tolerably safe situation if we keep clear of the branches of the trees and as far as may be from their trunks. If isolated trees afford the only shelter within reach, it is advisable to go _near_ them (within two or three yards of their projecting branches) but not _under_ them. Leaning against the trunk of an isolated tree during a thunderstorm is very dangerous. In this case the danger arises from the fact that the tree is a much better conductor than the air surrounding it, though a worse conductor than the human body. Hence, if a man stands against a tree, a line of least inductive resistance is likely to be determined through his body and continued upwards through the tree. Like considerations apply in the case of a person standing against a wall, or other high object, consisting of very imperfectly conducting materials and unprovided with efficient lightning conductors.

Footnote 7:

The apparently capricious way in which lightning often strikes is not inconsistent with this statement. It proves, however, that the line of least inductive resistance is partly determined by atmospheric or terrestrial conditions which are not perceived by the eye.

Footnote 8:

Is there any evidence to show that soldiers wearing spiked helmets, or marching with fixed bayonets, are specially liable to be struck by lightning? Various ancient writers—Cæsar, Seneca, Livy, Pliny, and others—mention luminous appearances (“Fire of St. Elmo”) presented by the javelins or pikes of soldiers during thunderstorms at night.

As to people indoors, we need only consider the case of those who are in buildings which are either not at all or only imperfectly protected by conductors; for, if a building is thoroughly protected, whatever is inside it is protected also. Indoors, as out of doors, we have to avoid forming part of a line of least inductive resistance. This consideration leads to such rules as the following:—Keep to the lower rooms of a house, rather than to the upper rooms; also keep as much as possible in the middle of the room you are in, but avoid being under a metal chandelier, or a lamp, or other object hung by a metal chain or wire; keep away from a stove or fire-place, _especially when a fire is burning_ in it; keep away from large metallic objects which are not in electrical connection with the ground, especially if they are above the level of the head (as mirrors, or pictures with gilt frames, hung against the wall), or below the feet (as an iron pillar or beam supporting the floor, or an iron staircase leading to a lower storey but not continued to one above). Franklin recommends “sitting in one chair and laying the feet up in another,” or as a further precaution “to bring two or three mattresses or beds into the middle of the room, and, folding them up double, [to] place the chair upon them.” But best of all he says is, “where it can be had, a hammock, or swinging bed suspended by silk cords equally distant from the walls on every side, and from the ceiling and floor above and below.” Doors and windows are better shut than open, but it does not seem that this condition is of much importance.

It may be added for the comfort of the timid that Arago concludes that the danger of being struck by lightning in a town (Paris) “is less than the danger of being killed in passing along the street by the fall of a chimney, or flower-pot, or of a workman engaged upon a roof; this latter danger being [he imagines] one which occasions very little uneasiness.” Also it seems to be the universal testimony of those who have been restored after being struck by lightning that they had not been conscious of either thunder or lightning. We may accordingly conclude that all danger from a given discharge is over, not merely by the time we hear the thunder, but as soon as ever we see the flash.

G. C. F.

INJURY TO GAS AND WATER-PIPES BY LIGHTNING.

The city gas company of Berlin, having expressed the fear that gas-pipes may be injured by lightning passing down a rod that is connected with the pipes, Professor Kirchhoff has published the following reply:—

“As the erection of lightning-rods is older than the system of gas and water-pipes as they now exist in nearly all large cities, we find scarcely anything in early literature in regard to connecting the earth end of lightning-rods with these metallic pipes, and in modern times most manufacturers of lightning-rods, when putting them up, pay no attention to pipes in or near the building that is to be protected.” Kirchhoff is of the opinion, supported by the views of a series of professional authorities, that the frequent recent cases of injury from lightning to buildings that had been protected for years by their rods, are due to a neglect of these large masses of metal. The Nicolai Church, in Griefswald, has been frequently struck by lightning, but was protected from injury by its rods. In 1876, however, lightning struck the tower and set it on fire. A few weeks before, the church had had gas-pipes put in it. No one seems to have thought that the new masses of metal which had been brought into the church could have any effect on the course of the lightning, otherwise the lightning-rods would have been connected with the gas-pipes, or the earth connection been prolonged to proximity with the pipe. A similar circumstance occurred in the Nicolai Church in Stralsund. The lightning destroyed the rod in many places, although it received several strokes in 1856, and conducted them safely to the earth. Here, too, the cause of injury was in the neglect of the gas-pipes, which were first laid in the neighbourhood of the church in 1856, shortly before the lightning struck it. The injury done to the school-house in Elmshorn, in 1876, and to the St. Lawrence’ Church, at Itzehoe, in 1877, both buildings being provided with rods, could have been avoided if the rods had been connected with the adjacent gas-pipes.

“If it were possible,” says Kirchhoff, “to make the earth connection so large that the resistance which the electric current meets with when it leaves the metallic conducting surface of the rod to enter the moist earth, or earth water, would be zero, then it would be unnecessary to connect the rods with the gas and water-pipes. We are not able, even at immense expense, to make the earth connections so large as to compete with the conducting power of metallic gas and water-pipes, the total length of which is frequently many miles, and the surface in contact with the moist earth is thousands of square miles. Hence the electric current prefers for its discharge the extensive net of the system of pipes to that of the earth connection of the rods, and this alone is the cause of the lightning leaving its own conductor.”

Regarding the fear that gas and water-pipes could be injured, the author says: “I know of no case where lightning has destroyed a gas or water-pipe which was connected with the lightning-rod, but I do know cases already in which the pipes were destroyed by lightning because they were not connected with it. In May, 1809, lightning struck the rod on Count Von Seefeld’s castle, and sprang from it to a small water-pipe, which was about 80 metres from the end of the rod, and burst it. Another case happened in Basel, July 9, 1849. In a violent shower one stroke of lightning followed the rod on a house down into the earth, then jumped from it to a city water-pipe, a metre distant, made of cast iron. It destroyed several lengths of pipe, which were packed at the joints with pitch and hemp. A third case, which was related to me by Professor Helmholtz, occurred last year in Gratz. Then, too, the lightning left the rod and sprang over to the city gas-pipes; even a gas explosion is said to have resulted. In all three cases the rods were not connected with the pipes. If they had been connected the mechanical effect of lightning on the metallic pipes would have been null in the first and third cases, and in the second the damage would have been slight. If the water-pipes in Basel had been joined with lead instead of pitch, no mechanical effect could have been produced. The mechanical effect of an electrical discharge is greatest where the electric fluid springs from one body to another. The wider this jump the more powerful is the mechanical effect. The electrical discharge of a thunder cloud upon the point of a lightning rod may melt or bend it, while the rod itself remains uninjured. If the conductor, however, is insufficient to receive and carry off the charge of electricity, it will leap from the conductor to another body. Where the lightning leaves the conductor its mechanical effect is again exerted, so that the rod is torn, melted, or bent. So, too, is that spot of the body on which it leaps. In the examples above given it was a lead pipe in the first place, a gas-pipe in the last place, to which the lightning leaped when it left the rod, and which were destroyed. Such injuries to water and gas-pipes near lightning-rods must certainly be quite frequent. It would be desirable to bring them to light, so as to obtain proof that it is more advantageous, both for the rods and the building which it protects, as well as for the gas and water-pipes, to have both intimately connected. Finally, I would mention two cases of lightning striking rods closely united with the gas and water-pipes. The first happened in Düsseldorf, July 23rd, 1878, on the new Art Academy; the other August 19th, last year, at Steglitz. In both cases the lightning-rod, the buildings, and the pipes were uninjured.”—_Deutschen Bauzeitung._ Quoted in _The Building News_, Sept. 10, 1880.

COLLIERY WORKINGS STRUCK BY LIGHTNING.

THE INSTITUTE OF MINING ENGINEERS.

A meeting of the members of the North of England Institute of Mining and Mechanical Engineers took place in the Wood Memorial Hall on Saturday, Mr. G. C. Greenwell in the chair, when the secretary read an account of an investigation which had been made into a statement that lightning had entered Tanfield Moor Colliery on the 12th of July last, and traversed the workings in several directions. Mr. Wm. Joicey kindly gave permission to examine the witnesses of the occurrence, and the workings of the colliery, so that a complete and accurate report could be drawn up of the circumstance; and on the 30th of July, Mr. C. Berkley, Mr. J. B. Simpson, Mr. W. H. Hedley, and the secretary went out to the colliery, and were met by Mr. W. Joicey, one of the owners; Mr. Pringle, the viewer; and Mr. Arkless, the resident viewer. The top of the working shaft at the colliery is 34 fathoms from the Shield Row seam. An incline bank leads northwards from the working shaft and ultimately reaches the day by a drift, and a little to the south is an up-cast shaft. The engine way leads south from the working shaft, and goes in-bye to a goaf. Between the goaf and the working shaft are two down-cast shafts. From what can be gathered the lightning passed down the working shaft and struck the flat sheets, and then divided itself into two parts, one of which went north up the incline way and probably passed out to the day by the drift, where it was supposed to have left traces of its exit in marks upon a bank near by. The other part went south along the engine way; but after passing a point where it was noticed its further course was not known. The thill of the seam is composed of soft sagger, and the roof of strong post, both of which would offer great obstruction to the absorption of the electric fluid; and the probability was that this portion of the fluid had been dissipated in the goaf, or had forced an exit by way of the down-cast shaft.

The evidence taken was appended.—Joseph Kirtley, back-overman, said a light, distinct but not very bright, fell and struck the flat sheets, and split up into several lights like a lot of lighted matches. He could only see the light for a moment among the tub wheels. It struck the puller-out, Wm. Watson, on the arm, and he complained that his arm was numb, and when he got home it was yellow from the wrist to the elbow. A heavy peal of thunder was heard very distinctly almost at the same moment. No injury was done either in the shaft or on the road where the lightning was said to have passed. He could liken it to nothing better than a box of matches all struck at once.—James Offord, onsetter, said he heard a crack like the report of a small pistol, and saw a light close to his feet.—William Watson, puller-out at the bottom of the pit, said he saw a flash of light come down and heard a noise like a gun: it struck on the plate or flat sheet. He saw the light divide when it struck. The light when it struck was very bright, but did not brighten up the place to any distance.—Thomas Chrisp, a deputy, said he saw something like a lot of fire flying, and thought the tram had cut the point. It was as though a person had trodden upon matches and they had gone off. The fire seemed a little larger than the light of a candle, and to the best of his judgment came along the metals.—John Greener saw a light on the rail about the size of a candle flickering, not steady. It appeared to travel along the rail, and as it passed the tram made a noise like the crack of a pistol, and he thought it was matches or something on the way that was cracking.—John Hagan, a putter, said he saw the lightning come along the plates. It caught him as it passed and gave him a queer feeling in the legs. It made a sharp, cracking noise in the plates like a gun.—George Chrisp, a siding minder, said he was about 50 yards from the shaft, and heard a cracking noise, and saw a bright light and flash of fire against the big winding sheave, two feet diameter, like five or six matches going off at once. There were no tubs running by at the time.—Matthew Hardy, an engine flatter, who was about 100 yards along the shaft siding, said he saw a light like a spark from a lamp, and there was a noise like a match being struck by a tub passing over it. The light appeared to be close to him on the rope, which was running.—It further appeared that the rails were fished; that it was not noticed whether the lightning came down the rails or the rope; that it was a self-acting incline; that a noise as of a pistol or gun shot was heard when the light came to the tram; that a similar noise was heard as the light left the tram; and that the metallic contact might have been broken here by a fish-plate being off. The gentlemen who conducted the inquiry had every reason to believe that the information thus obtained forms a valuable record of the occurrence, and places beyond doubt the possibility of lightning penetrating into the workings of collieries.—In the course of the discussion which followed the reading of the paper, Mr. A. L. Stevenson mentioned the occurrence of a similar circumstance at Page Bank, about 10 years ago.—Professor Herschell said that in order to produce an explosion the electric fluid must come in contact with a highly explosive mixture; and the occurrence in question showed the desirability of lightning conductors at collieries, and of the subject being investigated by mining and electrical engineers.—Cordial votes of thanks were given to the authors of the papers.—_Newcastle Daily Journal._ October 5th, 1880.

ACCIDENTS BY LIGHTNING AT THE SWAN COTTON MILL, CHADDERTON, OLDHAM. REPORT BY J. DOHERTY, A.S.T.E.

[On July 13th, 1880, during a thunderstorm, the large 400 light gas meter of this mill, though locked up in a cellar, and with no light near it, exploded, and the gas, which is supplied through a 4–inch main, was ignited. This was repaired, but on July 5th, 1881, during another thunderstorm, precisely the same accident occurred. At the request of Mr. Preece, F.R.S., Mr. Doherty, of H. M. Postal Telegraph Service, went and inspected the works, and forwarded the following report.—ED.]

_21st July, 1881._

A very careful investigation of the Swan Mill premises has been made, with a view of arriving at some explanation of the recent injury to the gas meter, which was undoubtedly caused by lightning. The building is a large one, having for its internal supports a number of cast iron columns running from floor to basement, and on the top of the building, I am told, there are numerous iron gutters; round the various rooms are carried large iron gas pipes, and in numerous instances this gas piping is dead against the iron caps of the columns, thus the lightning may have struck any portion of the building, and the current have been conveyed, safely, by the gas piping to the large gas meter, where an imperfect joint (electrically imperfect) existed, viz., an india-rubber ring placed between the faces of the iron joint. It is to be regretted that the connecting pipes were not on the premises at the time of my visit, otherwise I could have spoken with a greater degree of certainty, but I have not the slightest doubt in my own mind as to the insulating ring between the joints being the cause of rupture.

Tests were made, showing that the continuity of the present pipe is lessened by the existence of another india-rubber ring, and the oxidation of the connecting screws at another joint.

I advised the Directors of the Spinning Company to connect the outlet and inlet main pipes by iron or copper wire straps. I feel convinced that if this had been done prior to 5th July the accident would not have occurred.

J. DOHERTY.

ESSAY ON THE EFFECTS OF HEAVY DISCHARGES OF ATMOSPHERIC ELECTRICITY, AS EXEMPLIFIED IN THE STORMS OF THE SUMMER OF 1846 * * * * AND REMARKS ON THE USE AND APPLICATION OF LIGHTNING CONDUCTORS. BY E. HIGHTON, ESQ., C.E.

(Transactions of the Society of Arts for 1846–47. London. Sm. 4to).

(_Abstracted by G. J. Symons, F.R.S._)

The author’s primary object in studying the subject was the discovery of a method of protecting telegraphic apparatus from injury and danger. That has long been accomplished, but some remarks in the Paper seem worthy of extraction.

Mr. Highton went over St. George’s Church, Leicester, a few days after it was wrecked by the lightning. He says that the sexton told him that three minutes before the flash he had been tolling the curfew bell, and, “while in the belfry, he noticed a kind of light on the clapper of the bell, and heard also, as it were, a sort of hissing noise.”

[This seems to prove two things—(1) The fallacy of the old notion that ringing the church bells sent away thunderstorms (see also ante, p. (37);) and (2) that even very imperfect conductors, such as this conductorless steeple, carry off much electricity by the silent or brush discharge.—G. J. S.]

Mr. Highton found that the leaden flashings were frequently burst up, the lead being sometimes forced up somewhat like a miniature volcano. This he attributes to the explosion of confined atmospheric air, but obviously water converted into superheated steam would yield a greater expansive force.

The author quotes a case at Water Newton, Wansford, Northamptonshire, where, although the Church had tower and spire, and the whole roof was covered with lead, a tree 90 feet from the spire, and not one-third the height of the spire, was struck, but the Church was not. This the author attributes partly to the action of the leaves of the trees, and partly to there being no iron or other vertical spouting to the Church.

Mr. Highton’s “Practical Rules” are _literatim et verbatim_:—

1st. Where a building has any quantity of vertical metallic work, it is quite necessary, for its protection against Lightning, that it should have an artificial Lightning Conductor, (unless the materials of themselves form a natural one).

2ndly. It is very desirable, that all metallic circuits, especially those in a vertical direction, should be metallically connected with the system of Lightning Conductors.

3rdly. That, in many instances, a single insulated Lightning Conductor attached to a building may become positively injurious and dangerous; as it may cause many a cloud to discharge its electric force at that point, which would otherwise have passed over, and poured its power in some other channel.

4thly. That, where Lightning Conductors are employed, they ought to be thoroughly well erected, and every course or channel that the Electric fluid has open to it carefully considered, and a division of the charge in those quarters provided against.

5thly. That a Lightning Conductor, or a system of Lightning Conductors, where properly and scientifically erected, are perfect safeguards against the effects of heavy discharges of Atmospheric Electricity. But, if improperly applied, they may become a most dangerous addition to a building.

6thly. That it is essentially necessary for the safety of the public, that all public buildings, and especially churches, should, if naturally deficient in safe and secure Lightning Conduction, have artificial Lightning Conductors erected for their protection.

The above are given as a few general rules. It is difficult, however, and almost impossible, to lay down any fixed and definite rules for the erection of Lightning Conductors, to be applicable to _every_ building; as the very form, shape, and position of the building, and the _relative position_ of buildings in the immediate neighbourhood, so materially affect the data for the formation of those rules. In all cases, therefore, I consider it much better and safer for an Architect to call in a person of knowledge and experience in this branch of science, for directions for the proper erection of Lightning Conductors, than to trust to any printed rules whatever on the subject.

That, as it is better in cases of illness where life is in danger to call in a medical man than to apply oneself the remedies set forth in works on medicine, so is it better, in the protection of buildings from the disastrous effects of Lightning, to trust only to the opinions and directions of those who have given to this difficult branch of science their study and attention.

THUNDERSTORMS.

BY PROFESSOR TAIT, F.R.S.

[Delivered in the City Hall, Glasgow. Nature Aug. 12th, 19th, Sept. 2nd, 9th, 1880.]

(_Abstracted by W. H. Preece, Esq., C.E., F.R.S._)

While a few years ago no qualified physicist would have ventured an opinion as to the nature of electricity, now, thanks to Clerk-Maxwell, electric and magnetic phenomena are regarded as mere stresses and motions of the ether, and are brought within the resources of mathematical analysis.

Thunderstorms are accompanied by darkness, the result of the intense shadow of peculiar thick clouds charged with electricity, whose height varies from 30 yards to 3 miles. The air is never free from electricity. Snow, sleet, hail, and “luminous rain” are frequently indications of great electrification. The atmospheric electric charge is usually positive, and is probably the result of evaporation, but clouds themselves are more generally negative.

Lightning, as a source of light, is very brilliant, comparable even with the sun, but its duration is extremely short, hence its intensity is about equal to that of full moon. The motion of a flash cannot be detected; hence when people say they saw a flash going upwards or downwards, they must be mistaken. It is an optical illusion. The peculiar zigzag form, occasionally bifurcated, is that of a very large electric spark, varied by local electrification and heat.

The motion of electricity is due to a difference of potential or electrical pressure. The power of a machine is measured by the utmost potential it can give to a conductor, and the _time_ required to charge the conductor depends on its _capacity_. The damage which can be done by a discharge is proportional to the square of the charge, and inversely to the capacity of the receiver. Doubling a charge gives fourfold a shock.

Electricity is entirely distributed on the surface of conductors. The quantity per square inch of surface is _the density_, and the density varies with the form of the conductor. On a very elongated body, terminating in a point, the density becomes so exceedingly great that the outward pressure of the electricity tending to escape forces a passage through the surrounding air. Proper lightning rods must be surrounded with a number of sharp points, lest one should be injured. The proper function of a lightning rod is not to parry a dangerous flash of lightning: it ought rather, by silent but continuous draining to prevent any serious accumulation of electricity in a cloud near it. Hence it must be thoroughly connected with the earth. At Pietermaritzburgh, which is well covered with lightning conductors, thunderstorms are frequent, but they cease to give lightning flashes whenever they reach the town, and they begin to do so as soon as they have passed over it.

The violent disruptive effects produced by lightning are principally due to the sudden vaporization of moisture. Heated air conducts better than cold air. Hence the killing of flocks and herds.

There is little or no danger inside a thunder-cloud. Thunder-bolts (so called) are due to the vitrification of sand through which a discharge has passed. The smell that accompanies lightning is due to ozone.

Sheet lightning and summer lightning are due to the lighting up of the clouds by flashes of forked lightning not directly visible to the spectator, sometimes even beneath the horizon.

Thunder corresponds to the snap of the electric spark, intensified and re-echoed from clouds and surfaces. A longer zigzag flash acts successively and intermittently from portions farther and farther from the listener. Hence the crash, clap, rolling and pealing of thunder. The extreme distance that it is heard is about ten miles, although guns have been heard fifty miles.

Fireball or globe lightning undoubtedly exists and is probably due to a species of natural Leyden jar, very highly charged, which no lightning rod can destroy, except, perhaps, a close net work of stout copper wires.

Water is the chief agent in thunderstorms. Copious rain and hail always accompany them. Hot moist air precipitating its moisture as clouds as it ascends, cooling by expansion but warmed by the latent heat of the condensed vapour is the main spring. The condensation of aqueous vapour is accompanied by an enormous development of energy. A fall of one-tenth of an inch of rain over the whole of Britain gives heat equivalent to the work of a million millions of horses for half an hour. The mere contact of particles of aqueous vapour with those of air produces a separation of the two electricities. Aqueous vapour condenses into cloud particles, and the agglomeration of cloud particles into rain drops would enormously increase the original potential of the electrified vapour.

The column of smoke and vapour discharged by an active volcano gives out flashes of lightning. Cloud caps on mountains frequently do the same. Ascending currents of air mean change of density, difference of pressure, heat condensation, and all the conditions required to produce a thunderstorm, with its effects forming “one of the most exquisite of the magnificent spectacles which nature from time to time so lavishly provides.”

ON THE PROTECTION OF BUILDINGS FROM LIGHTNING.

BY CAPTAIN J. P. BUCKNILL, R.E.

(_Abstracted by W. H. Preece, C.E., F.R.S._)

In the first part of his paper the author popularly explains his own views of electricity, the causes of thunderstorms, and the purpose served by a lightning conductor. He urges the theory that lightning is mostly to be feared by those who live on well conducting areas; and that non-conducting areas, such as chalk hills, suffer the least, because their inductive influence on charged clouds is less than in the former case, even though they be on low ground. Points act as leaks, warding off lightning by neutralising harmlessly the opposite electricities. The trees of a forest act as a mass of points, silently discharging thunder clouds. The potential of a thunder cloud is often a million and a-half volts. The function of a lightning conductor is “(first) to attract the lightning to another spot if possible, and (second) to arrange that even if the building be struck, the work shall be given out at other portions of the path of the stroke.”

He advocates strange views as to the space protected by a lightning conductor, which, if true, would tend to show that there is no safety in lightning conductors at all, for according to him, the safe area rule may be upset in practice by all sorts of accidental circumstances. He has, however, not grasped the meaning of the rule. He advocates the use of iron as the best metal to use, specifying a weight of 2 lbs. per foot. He thinks wire ropes are more easily applied than rods, ribbons, or tubes, and prefers a rope 1·2 in. diam. of six strands of seven No. 11 B.W.G. wire, each round a hemp core—costing about 5d. per foot. Conductors should be specified in terms of electrical units, viz.: ·3 ohms per 1000 yards, and be continuous. Every unavoidable joint should be soldered. He has found in practice many bad joints, especially in copper conductors. At Tipner one gave 10,000 ohms, and one in the Isle of Wight 700 ohms. Each joint was apparently quite sound. He considers that lofty conductors require no additional conductivity per unit of length, and that high lightning rods are only required in exceptional situations.

Several points are preferable to a single point, because the “gathering power” is increased thereby, and the chance of lightning striking other things in the immediate vicinity of the conductor is proportionately diminished; the top of the rod is less likely to be fused when struck, the stroke being divided between the various points; and also because the brush discharge is thereby facilitated. He dwells with much emphasis on the importance of the earth connection, which he regards as a joint, and advocates greater surface than is usual at present. He illustrates an excellent deep earth connection formed by a galvanised cast-iron pipe, 10 feet long and 1 foot in diameter, sunk in a well below the water level in the dryest season. He insists that both deep and shallow surface earths are required.

Lastly he insists on periodical inspection, and the careful application of electrical tests. In an appendix he describes his own testing arrangements, with the results of nearly 500 tests made by him for the War Department, from which he concludes “that _with the lightning conductors erected as they are at present by the War Department_, electrical testing is of small value.” Nevertheless, in spite of this strong condemnation he asserts that the conductors now existing on our magazines and fortifications have never yet failed.

SPECIFICATION (No. 3925. September, 1880) of SAMUEL VYLE. LIGHTNING CONDUCTORS.

(_Abstracted by G. J. Symons, F.R.S._)

The invention may be divided into two parts. In the first place, the inventor proposes that in lieu, for instance, of the central strand of a seven-strand copper wire rope, there shall be a central wire insulated from the others, and only connected to them at the junction with the upper terminal, while at the bottom this insulated wire is led up from the earth to some place where it is easy of access.

Secondly, there is a differential galvanometer, resistance coil, and other apparatus, which being connected with the conductor and with the insulated wire, will enable the efficacy of the conductor to be read off at any time.

ON THE PARTIAL PROTECTION OF BUILDINGS.

(_By Prof. T. Hayter Lewis, F.S.A._)

The following are suggestions whereby the ordinary materials used in building may, to some extent, be utilised as protectors against lightning:—

(1) When the roofs and sides of a building are covered with galvanized sheet iron on a framework of wood, if these coverings have good earth contacts, either by themselves or through the ordinary iron rain-water pipe, the building may be considered safe.

(2) Cottages and small houses have usually iron eaves gutters, slate or tile hips and ridges, cement flashings, and iron rain-water pipes. If the joints be sound, and the earth at the foot of the rain-water pipes be moist, the houses will, to a considerable extent, be protected from the level of the eaves gutters downwards. But as they will be quite unprotected about that level, a wire rope or metal tape from the top of the highest chimney to the gutters, which will very much diminish the risk, is desirable.

(3) In larger buildings the gutters, rain-water pipes, hips, ridges, and flashings of the roof are often made of lead. If the pipes have good earth contacts, and conductors be fixed from the chimneys or other projections to the lead-work, the buildings will be to some extent protected.

(4) When the hips and ridges of roofs are of slate, terra cotta, or other non-conducting materials, conductors along the ridges, connected with the rain-water pipes, and with points along the ridge, and to the chimneys, will be required.

* * * * *

But all the buildings above described would be exposed to the risk of imperfect joints, bad workmanship, &c.; so that no structure can be considered as secure unless it be protected by one or more conductors of approved size and metal, and with carefully constructed connections and earth contacts.

INDEX TO THE APPENDICES.

NOTE.—It must be distinctly understood that no responsibility for the statements or views indicated by this index or set forth in the appendices is assumed either by the delegates collectively or by the Editor.

Abel, Prof., on Mr. Preece’s Paper, 102

Academy of Sciences, Report made to, 51 _et seq._

Accident at Athelney, Bournemouth, 201

„ at Carmarthen, 217

„ at Caterham, 210

„ Masulipatam, 206

„ Trolley Bottom, Herts, 196

„ in Belgium, 129

„ in England, 38, 129

„ in low-lying parts of France, 129

„ in mountainous parts of France, 129

„ to a French frigate, 200

„ various, 126

„ within small areas, 201

Action, Mechanical, of lightning, 85

Adams, Prof. W. G., Abstracts by, 76, 82

Addiscombe, chimney of house struck, 38

“Ætna,” Ship, struck at Corfu, 88

Aigrettes or brushes of points, 139 (_See_ POINTS MULTIPLE).

Air in electric field in state of strain, 135

„ terminals (_See_ POINTS).

Alatri, Cathedral of, 126

Allen, R., Letter from, 183

All Saints’ Church, Nottingham, struck, 37

Alphand, M., his Report, 67

Alphington Church, near Exeter, struck, 37

America, gutters and water pipes used, 125

Analysis of Manufacturers’ Remarks, &c., 17

Anderson, R., on Lightning Conductors, 120

„ on testing, 111, 127

Androuët, M., his assistance, 225

Angle iron conductors, advantages of, 111

Angles, Sharp, to be avoided, 11, 16, 28, 71, 94, 99, 178

„ useful for discharging electricity, 111

Arago, on bends in conductors, 94

„ „ earth terminals, 95

Architects, Royal Institute of British, Report of, 27

Area protected (_See_ PROTECTION, AREA OF).

„ Sectional, 15, 18, 22, 49, 110, 131, 132, 195, 223

„ „ insufficiency of, 63

„ „ varied with length, 7, 9, 12, 13, 14, 19, 20, 24, 131

„ „ not varied with length, 4, 16, 243

Asted, Col., Report of Accident, 206

Atmospheric Electricity, 112, 119

„ „ by D. Brooks, 117

„ „ by R. Phillips, 98

„ „ origin of, 117

Attachment should always be of same metal as conductor, 21

„ to building, 7, 8, 9, 11, 13, 14, 16, 21, 24, 31, 39, 81, 99, 103, 115, 125, 130, 193

Attraction, Conductors do not attract lightning, 71

„ Specific, equal in all bodies, 73

Attractive points, 127

Austria, Accidents in, from Lightning, 126

Aylmer, J., his assistance, 228

Ayrton, Prof., Abstracts by, 43, 83, 85, 90

„ „ on Clerk Maxwell’s Lightning Conductors, 132

„ „ on Indian telegraphs, 102

Babinet, M., his Report, 60, 66

Backstroke of lightning dangerous, 85

Baker, A. J., his Report, 34

Ball, Hollow, with small points (_See_ POINTS MULTIPLE) 13, 23

„ is a point when compared to a cloud, 73

„ lightning, (_See_ LIGHTNING BALL.)

Ballu, M., his Report, 67

Band (_See_ TAPE and PLAIT).

Barns full of new hay likely to be struck, 125

Barque “Southern Queen” struck, 205

Bar of iron, bad joints in, 116

„ Melted by lightning, 61

„ Rectangular flat, 74

„ Small, become heated, 116

Base of conductor should bifurcate, 65, 243

Batteries, Casemated, 70

Bayonne, Powder magazine at, 87

“Beagle,” H.M.S., struck by lightning, 195

Beams, how connected, 10

Becquerel, M., his Report, 60, 66

„ on discharge of lightning, 131

„ on conducting power of metals, 124

Belgrand, M., his Report, 67

Bell, Hornsby & Co.’s experience, 193

Bells in church steeple, 85

Bell wire acts as a conductor, 39, 195

Bends, Sharp, to be avoided (_See_ ANGLES).

Berehaven lighthouse struck by lightning, 208

Bisby, Mr., of Leeds, his conductor, 75

Bishop’s Rock Lighthouse, 190

Blitzableiter, Von G. Karsten, 114

Blunt conductor (_See_ BALL _and_ POINTS).

Boat, Packet, struck (_See_ SHIPS) 61

Bolts, Iron, attracted lightning, 40

„ to be connected with conductor, 11

Books on Lightning Conductors, Catalogue of, 143

Bootham Bar, York, 219

Borrel, M., his views, 226

Boy on pony, pony killed, boy escaped, 48

Branches, Connecting, 183

Brandon, D., his Report, 34

Brass not a reliable metal, 62, 124, 227

„ wire rope used in Bavaria, 124

Break in conductor not fatal, 53

„ „ „ to be avoided, 63

Brescia powder magazine blown up, 76

British Association Report, 1860, 46

Brixton Church struck, 84

Broek, R. Van der, Abstracts by, 114, 119, 137, 138, 140, 141

Brook, Conductor to be carried to it, 14

Brooks, D. 103, 181

Brough, Mr., on Lightning Rods, 19, 49, 181

Bruntcliffe, Yorkshire, Gunpowder store destroyed, 74, 216

Brussels, Town Hall at, Lightning protector at, 138

Brydone, Mr., Report of an accident, 85

Buchanan, G., on gas works chimney, 89

Bucknill, Capt., on the protection of buildings, 243

Building, containing masses of metal, 61

„ continually under attacks, 123

„ injured, though protected, 27, 128

„ Long, to have several conductors, 25, 202

„ Metallic, safe, 72

„ protected by cage of wires, 132

„ struck from, 1589 to, 1879, 126

Burges, Mr., 190

Cable conductors (_See_ ROPE).

Cagniard de Latour, M., his Report on Points, 60, 66

Calcutta, Report on conductors at, 117

Callaud, A., his Treatise, 103

„ his grapnel in basket of coke, 131

Canton, Mr., his experiments in London, 80

Capacity of conductors, 127

Caps, Cast-iron, to chimneys, 103

Carbon in well, 180

Carmarthen, Accident at, 217

Casing of lead or wood for iron earth terminals, 125

Catalogue of works upon lightning conductors, 143

Caterham, accident at, 210

Cathedral of Alatri, 126

Cavendish, Hon. H., his Report, 76, 79

Cemented water tank, iron conductor in it, 130

Chain conductors melted, 61, 62

„ though broken, still useful, 54

„ objectionable, 9, 61, 62, 88, 123

„ Early use of, as conductors, 122

„ Old iron, for earth terminals, 74, 204

Chapel, Rycroft, struck, 45, 46

Chapman, Gen. Sir F. E., his Report, 72

Charcoal for earth terminals, 12, 16, 58, 125, 126

Charles, M., his Report on Instructions for erecting conductors, 57

Cheapness of galvanized iron, 132

Chimney, Accidents to, soon after erection, 194

„ Granite, in Plymouth Dockyard, struck, 73

„ Metal Caps to be joined to Conductors, 125

„ New, contain much moisture, 194

„ not struck that had conductors, 193

„ of Edinburgh Gas-works, 89

„ over, 90 feet have conductors, 193

„ rod to be on, 100

„ rope on, liable to corrosion, 125

„ Shafts, copper band round top of, 9

„ Stacks are Conductors, 7

„ struck, 27, 28, 40, 45, 193, 194

„ struck because of heated air, 113

„ struck before completion, 94

„ struck that had no conductors, 38, 193

„ very rarely struck at Glasgow, 193

„ with soot dangerous conductors, 106

„ Zinc, struck, 37

Church, Brixton, struck, 84

„ Charles, at Plymouth, 86

„ Christ, Carmarthen, 217

„ Rosenberg, in Carinthia, destroyed, 1730, 123

„ St. Bride, Fleet Street, damaged, 126

„ Ste. Croix, Ixelles, struck by lightning, 140

„ St. George, Leicester, damage to 126, 240

„ St. Giles, Cripplegate’s truck, 196

„ St. Mary, Genoa, 126

„ Southampton, damage to, 126

„ Steeple at Bodmin, destruction of, 202

„ struck, 29, 37, 106, 126, 137, 199

„ struck near Isleworth, 199

„ tower, with pinnacles, 10, 29, 137

„ towers struck in past, 400 years, 202

„ with lightning conductor, 128

„ without lightning rods damaged, 126

Cinders with grating (_See_ EARTH TERMINALS).

Circuit to be tested by galvanometer, 130, 244

Cistern dangerous for base of conductor, 64

Claire-Deville, M., his Report, 67

Clamps, Iron, acted as conductors, 43

Clark, J. E., Accident at Bootham Bar, York, 219

„ Latimer, Abstracts by, 103, 106

Clay, Conductor to be taken below surface of, 14

Clevedon Church struck, 126

Clifton, E. N., his Report, 41

Clips, Gun-metal, 24

Clouds are not perfect conductors, 101

Cluster of points (_See_ POINTS MULTIPLE).

Coke, broken, better than charcoal, 116

„ prevents action of sulphur, 120

„ round conductors, 9, 116, 118, 126, 131

%center%(_See_ EARTH TERMINALS).

Cole Brothers, 192

Colliery Chimney near Sunderland struck, 193

„ Workings, Lightning in, 237

Colson, J., his Report, 28, 34

Commission on damage by lightning, 127

Comparative resistance to fusion, 141

„ „ rupture, 141

Conducting power depends on amount of copper in conductor, 200

„ „ of metals, 74, 124, 131, 139

„ „ of wires, 177

Conduction, is it a question of surface or of mass? 15, 18, 49, 132

Conductive capacity deficient in trees, 127

Conductor at ends of buildings has radius of protection lessened, 134

„ Construction of, 63, 107, 178, 179

„ Cost of, for Houses of Parliament, £2314, 122

„ damaged by holdfasts, 115, 193

„ destroyed at ground line, 131

„ partly destroyed, yet useful, 62

„ deteriorate, 127

„ dimensions of (_See_ SIZE OF).

„ do not attract lightning, 88

Conductor, every, should be complete in itself, 22

„ Examination of, 9, 72, 102, 111, 124, 127, 130, 131, 132, 179, 244

„ Expansion of, 11, 70, 125, 128, 226

„ First, 121

„ „ in England, 85, 121

„ „ in Europe, 122, 129

„ for lighthouses, 195, 199

„ for iron ships, 122, 200

„ for wooden ships, Snow Harris’s, 195, 199

„ for steeples, with horizontal bands, 125

„ how to be connected with metal portions of buildings, 65, 125, 126, 128

„ imperfect, Effect of, 21, 209

„ in contact with metal in chimney, 111

„ influenced by new water and gas mains, 127

„ influenced by trees, 127

„ is it to be a rope, rod, tube, or band?, 18, 132, 195

„ joints in (_See_ JOINTS).

„ laid in underground water, 128

„ led into cemented water tank, 130

„ „ water butt, 107

„ Main, 183

„ must protect ridge, gable ends, and eaves, 112

„ not to be insulated (_See_ INSULATION).

„ not to rise less than, 15ft. above chimney, 122

„ now same as Franklin’s, 124

„ number necessary, how determined, 51

„ of copper, 107, 130

„ „ and zinc wire, 205

„ „ tape, 206

„ „ rope, 196, 203

„ „ the best, 125

„ of hollow tube, 122, 196

„ of Hotel de Ville, Brussels, 126

„ of iron, 55, 107, 125, 131, 139, 140

„ of large surface better than rod, 113

„ of links of copper, 202

„ of numerous thin wires, 139

„ of solid bolt, 196

„ of zinc wire melted, 107

Conductor on buildings, to be linked together, 204

„ on churches at Torquay defective, 130

„ on ridge of roof, 125

„ outside, 60, 126

„ Points of (_See_ POINTS.)

„ properly made, and properly fixed, insures safety, 12

„ protects conical space (_See_ PROTECTION, AREA OF).

„ reached water without earth plate, 128

„ Ridge, 68, 177

„ should extend above building, 106, 202

„ should it present a large surface section? (_See_ AREA SECTIONAL).

„ size of, 10, 12, 18, 19, 22, 86, 119, 125, 126, 129, 131, 192, 194, 202, 214, 223, 225, 243

„ spirally coiled up, 128

„ struck by lightning, 128

„ supposed perfect, proved defective, 131

„ theory and action of, 106

„ to be close to wall of building, 11, 15, 86

„ to be continuous, 179

„ to be fixed by iron staples, 125

„ to be, 4 inches from walls and roofs, 118

„ to be inside, 126, 225

„ to be on side most exposed to weather, 60

„ to be of metal of high conductivity, 131

„ to be symmetrically arranged, 105

„ to earth by shortest route, 126

„ to gas and water mains (_See_ EARTH TERMINALS).

„ to Middlesboro’ Hospital, 204

„ to rest in hooks, 179

„ to St. Alphege Church, Greenwich, 206

„ to St. Michael’s Church, Blackheath, 205

Cone of platinum (_See_ PLATINUM).

Conic Terminals (_See_ POINTS).

Conference Circulars by the Lightning Rod, 3, 175

Conic Space, protected (_See_ PROTECTION, AREA OF).

Connection (_See_ EARTH TERMINALS, _and also_ JOINTS).

„ of metallic masses, 9, 10, 76, 77, 186

„ „ not necessary, 126

Contact between iron and copper to be avoided, 111

Continuity between point and earth contact, 129

Contraction to be provided for, 70, 125, 128

Copper and iron form best conductors, 119

„ and iron soldered, 107

„ and zinc wire bad for conductors, 205

„ Australian, 124

„ better than silver, 139

„ conducting power of, 19, 124, 131, 139

„ conductors, 18, 70, 86, 117, 119, 125, 126, 130

„ conductor too small, 126

„ earth plate in dry sand, 128

„ is it alone to be used?, 18

„ less liable to oxidise, 131

„ not to be in contact with galvanized iron, 102

„ nuts, 192

„ or iron conductors, 70, 192

„ plates, bent, 125

„ plate ending for conductors, 128

„ plates to provide for expansion, 125

„ points (_See_ POINTS).

„ preferred to iron, 131

„ purity of, 19, 124

„ rarely used, 125

„ tape recommended, 206

„ rod conductor, 185, 186, 202

„ rod, ½ in. diam. has never been fused, 125

„ rod on Eddystone Lighthouse, 184

„ rope conductor carelessly fixed, 196

„ rope conductor insulated, 194

„ rope to be used, 125,131

„ „ of thick wires

„ Russian, 124

„ Spanish, 124

„ tubing, 74, 122

„ wire fused throughout its length, 195

„ wires, deterioration of, 114

„ wire rope applied to St. Paul’s Cathedral, 131

„ wire rope, dimensions of, 8, 223

Corn stacks fired by lightning, 187

Coronal to be placed on chimneys, 132

Corrosion of joints of rod, 126

Cotton Mill, Explosion at, 239

Coulomb, M., his Report, 51, 53

Couplings, form of (_See_ JOINTS).

Coutt’s Brewery, a rod at, 89

Cramps, iron, stones held by, 29

Cross, Metal, 53, 85, 227

Croxton Park, trees struck, 48

Cruickshank, A., his Report, 44

Crutches on roof to carry rod, 52, 227

Current, what it is, 100

Cutting and Co., their conductor coupling, 216

Cylinder in water (_See_ EARTH TERMINALS).

Cylindrical rod or wire rope the best, 134

D’Alibard, M., his experiments at Marly, 80

Damage to building by alteration of position of safe, 127

D’Amico, Sig., 179

Damp air, a conductor, 48

Dampness of new chimneys cause of being struck, 194

Danger of explosion from use of gas pipes, 201

Davioud, M., his report, 67

Davis, H. D., suggestion about gas pipes, 201

„ Jno. & Son, their answer, 14, 15, 17

Davy on conducting power of metals, 124

Deaths from lightning, 100, 126

De la Place, M., his Report to French Academy, 51

De la Rive says blunt points or balls equally effective, 106

De la Rue’s (Dr. Warren) experiments, 133, 135

Delaval, M., his Report, 76

Delieul, Messrs., points made by, 66

De Lor, M., his experiments in Paris, 80

Denmark, lightning conductors in, 176

Desains, M., his Report, 67

De Saussure’s neighbours frightened at his conductors, 122

De Senarmont, M., his Report on points, 66

Designs for protecting private houses, 125

Despretz, M., his Report on points, 66

Destruction of conductors by use of iron wall eyes, 131

Dimensions of conductors (_See_ CONDUCTORS, SIZES OF).

Dimensions of upper terminals, 17, 18

Discharge diverted from conductor by an anchor, 128

„ from thunder cloud over plane surface would be vertical, 127

„ of electricity by trees lessens energy of lightning, 127

„ of electricity of high potential obeys laws of Ohm, 134

„ of lightning—Earth contact, 131

„ passes through conductor, Faraday, 132

Discharging fork to be attached to lower end of conductor, 11, 231

Doherty, J., on explosion at Swan Cotton Mill, 239

Doors, copper, to magazines, 74

„ iron, to powder store, 76

„ lightning passed out of, 27, 48

Drain, conductor to be led into, 14

Duc, M., his Report, 67

Dugmore, Mr., his evidence, 198

Duhamel, M., his Report, 60, 66

Dulong, M., his joint instructions, 59

Dum Dum, accident at, 181

Du Moncel, Comte, 67, 226

Dungeness Lighthouse, 183, 186

Duprez, M., his statistics of buildings and ships struck, 91

„ on height of points, 96

Dymond, E. E., Abstracts by, 51, 108

Earth, “bad”, 110, 117, 126, 127, 209, 210, 218

„ moist, better than a well for end of conductor, 74

„ plate, pipe, or tube, 9, 24, 100, 114, 115, 118, 120, 128, 177, 179, 186, 231

„ plates at Torquay carried out to sea, 130

„ „ unnecessary, 16

„ Terminals, 11, 13, 14, 15, 21, 56, 95, 102, 106, 109, 116, 126, 131, 140, 180

„ „ at base of rain water pipe, 132

„ „ bad, 110, 117, 126, 127, 209, 210, 218

„ „ Borrell’s, 226

„ „ Callaud’s, 104, 125, 131

„ „ destroyed in moist earth, 116

„ „ Discussion on, 131

„ „ Duplicate, 65

„ „ important, 11, 71, 126, 131, 243

Earth Terminals of conductors in iron box, 126, 231

„ „ of conductors, Stotherd, Lt.-Col., 130

„ „ in wells, 15, 56, 60, 74, 77, 100, 118, 126, 139, 179, 180, 231, 243

„ „ iron should be galvanised, 120

„ „ length of, 11

„ „ multiple, 139, 243

„ „ Oxidation of, 125, 131

„ „ Rules for, 64, 72, 132

„ „ to be accessible, 68

„ „ to be carried away from building, 107

„ „ to be connected, 120

„ „ to be deep and wet, 107

„ „ to be good, 126, 130

„ „ to be in moist ground, 21, 52, 55, 56, 58, 74, 113, 118, 123, 124, 125, 126, 131

„ „ to be tested, 111, 131

„ „ with charcoal cinders or coke, 9, 12, 16, 23, 24, 58, 104, 116, 120, 125, 126, 131

„ „ with coil of conductor, 9

„ „ with galena, &c., 58

„ „ with gas pipes (_See_ GAS).

„ „ with iron forks or harrows, 11, 131

„ „ with old iron, 74, 204

„ „ with water, 52, 53, 67, 68, 126, 130, 140

„ „ „ pipes, 9, 26, 46, 55, 56, 68, 118, 125, 126, 127, 128, 132, 231, 235, 243

Eddystone Lighthouse, 183, 184, 186, 189, 191

Effects of climate on copper and zinc wire ropes, 205

Electric current checked, 193

„ discharge takes path with best conduction, 127

„ fire not diverted from its path by rod, 125

Electricity a terribly explosive power, 72

„ Atmospheric, 98, 112, 117, 119

Electricity, frictional and atmospheric the same, 82, 112

„ carried off by water pipe, 126

„ for telegraphic purposes follows Ohm’s laws, 133

„ is force, not matter, 100

„ of earth negative—atmosphere positive, 112

„ Static, laws of, 132

„ will leave small conductors for large ones, 204

Electrodes, 110

Elevated rods preferable to low conductors, 79

End of conductor, lower, to be coiled up, 9

Energy of lightning lessened by trees, 127

England, accidents from lightning, 126

Escurial, no conductor on, 100

Examination of Conductors (_See_ CONDUCTORS, EXAMINATION OF).

Expansion of conductor to be allowed for, 11, 70, 125, 128, 226, 229

Experiment on wire across Thames, 121

„ on plait of copper and zinc wire at Blackheath, 205

„ with a very thin strip of tinfoil, 199

„ with glass rods, 121

Explosion of a gas meter, 239

Explosions, electrical, their cause, 81

Extent of surface does not favour lightning discharges, 134

Eyes for fastening conductors, 99, 115 (_See_ ATTACHMENT).

Faraday on conductors, 83, 84, 89, 102, 132, 183, 186, 187, 189, 190, 195, 196, 199.

Field, Rogers, C.E., on accident at Caterham, 210

„ on ventilating pipes, 216

Fire of inflammable materials, 127

First conductor erected in England, 85, 121

First conductor fixed in Europe at Hamburg, 122, 129

Fixing conductors to ships, 87

Fizeau, M., his report on powder magazines, 66, 67

Flagstaff should have a conductor, 70

„ struck, 44, 187, 196

Flashing, Lead, how to connect wire rope with, 10, 11, 34

Flash, lightning, effects of, 84

Flow of electricity through conductors, 133

Flues copper, 183, 185

„ lightning passed down, 38, 39

„ warm, and an iron grate, a dangerous conductor, 101

Forest Hill, chimney of house struck, 38

Forms of upper terminals (_See_ POINT).

Formula for determining area protected (_See_ PROTECTION, AREA OF).

Foster, Prof. G. Carey, on Personal safety, 233

Fountains, Public, conductor lead away from, 56

Franklin, Dr., and wet rat, 85

„ discovered pointed metal best conductor, 121

„ erected lightning rod to his house, 121

„ experiments, 79, 84

„ „ repeated by Buffon & Dalibar, 115

„ first conductor was melted, 116

„ his report to French Academy, 51

„ on cold fusion, 102

„ on connection of lightning rod, 54

„ report on Purfleet, 76, 126

„ round rod best, 114

„ success in pushing use of conductors, 121

„ tried his kite successfully, 121

Freeman & Collier, their answer, 10, 17

French instructions, 51

„ „ on area protected, 22

Fresnel, M., his instructions, 59

Frost, A. J., Abstracts by, 99, 118

Fusion, metals which resist, only to be used, 139

„ of defective conductor, 215

„ of rod, Wheatstone on, 83

Gable near conductor struck by lightning, 28

Galena, and melted sulphur, Bed of for end of conductor, 58

Galvanic action between iron and copper, 111, 130

„ of wet and smoke on conductors, 205

Galvanised conductor painted, 139

„ iron, 19, 67, 68, 72, 101, 120, 124, 125, 132, 139

„ not to be in contact with copper, 102

Galvanised iron best material for earth contact, 130

Galvanometer for testing earth currents, 131

Gas and water mains, 113

„ „ „ utilisation of, 9, 28, 37, 39, 44, 72, 100, 102, 103, 108, 114, 117, 125, 126, 128, 138, 201, 231, 235

Gas coke for earth terminal, 23, 24

Gases from chimney injure conductors, 111

Gas ignited, 219

„ meter exploded, 239

Gasometer struck, 43

Gas-pipes, Soft metal, not to be used as conductors, 108

Gavarret’s, M., experiments, 139

Gavey, J., on accident at Carmarthen, 217

Gay Lussac’s iron conductor recommended, 104

German “reception rod” of iron, 125

Geneva cathedral, 103

Genoa, St. Mary’s Church, 126

Gilbert, Dr. (1600) magnetic and galvanic action one force, 120

Gilt point (_See_ POINT GILDED.)

Girard, M., his instructions, 59

Girders, how connected, 10

Glass, foundation of house insulated, 118

„ insulators (_See_ INSULATORS.)

„ repeller, 83, 185, 186

Globular Lightning (_See_ LIGHTNING, BALL).

Goldie’s, Mr., experience, 193

Governments, French and English, size of rod sanctioned by, 12

Grapnels and gratings for earth plates, 125, 126, 131

Gray, J. W. and Son, their answer, 7–9, 17

“Gridiron,” Termini of ribs pointed, 23, 24

Groome’s, J. E., evidence, 196, 197, 198

Ground connection (_See_ EARTH TERMINALS).

„ containing ironstone, 48

Guillemin’s, M., opinion, 132

Gunpowder stores, conductor, how to be fixed, 82

Gutters, Metallic, 40, 41, 45, 46, 47, 60, 125, 213

„ must be connected with conductor, 60

„ utilization of, 47, 125, 244

Guyton, M., his practice with charcoal, 58

Haigh & Son’s Colliery, 74, 216

Harris, Sir William Snow, Crown adviser, 8

„ combated the idea that rods attracted lightning, 122

„ conductors to ships and buildings, 83, 122, 130, 196

„ in conflict with Faraday, 195, 196, 200

„ on Sectional Area, 110

„ on copper conductors, 202

„ on expense of conductors, 49

„ on fusion, 86

„ on hollow or solid conductors, 74

„ on relative conductivity of metals, 71

„ on shipwrecks by lightning, 90

„ on thunderstorms, 85

„ Principles adopted by, 70, 101

„ regarding insulators, 15

„ report on safety of conductors, 72, 110

„ says discharges pass over surface, 132

„ suggestions issued in army circulars, 122

Hauksbee, F., F.R.S., similarity of electric flash and lightning, 121

Hawksley, T., his report, 37

Hay a bad conductor, 127

Hay newly gathered, inflammable, 127

Heated smoke from chimney, a conductor, 132

Heckingham poorhouse struck, 87

Height of rods, 120, 124, 125, 139, 177

Hemispheres of brass, experiments with, 105

Henly, W., his report, 78, 79

Henry, Prof. Joseph, on construction of lightning rods, 99, 181

Herring’s, Mr., evidence, 196

Heryet, Chas. J., his opinion, 206

Higginbotham’s, Mr., evidence, 194

High buildings a source of safety to lower ones near, 12

Highton, E., on lightning conductors, 239

Hill, A., his Report, 37

Hine, G. J., his Report, 37

Hine, T. C., and Sons, Architects, ground plan of Nottingham Castle, 26

Holborn Union Infirmary, Upper Holloway, struck, 39

Holdfast, brass, 16

„ copper, 7, 8, 13, 16, 21, 24, 39

„ driven in too tight, 16, 193 (_See_ ATTACHMENT.)

Hole in ship’s side, made by lightning, 62

Honeyman’s, J., evidence, 194

Hook and rings used as joints, 94

Hoop iron in brickwork of chimneys struck, 46

Hoops round chimney, 89

Hopkins, Rev. G. H., his Report, 30

Horizontal conductor, 71

„ conductors for steeples, 125

Horsley, Bishop, his Report, 79

Hotel des Invalides, Paris, conductor on, 86

Hotel de Ville, Brussels, conductors of, 126

House at Bethnal Green cut in two by lightning, 41

„ at Bournemouth with, 7 conductors, 199

„ at Cannes (France) struck, 198

„ near trees struck, 127

„ of Parliament protected by Harris’s conductors, 122

„ with two separate conductors, 128

Hugueny, M. F., on “Le coup de foudre de l’ile du Rhin”, 99

Ignition depends on retardation of discharge, 127

Infirmary, how to be protected, 10

Ingenhousz’s, Dr., experiments, 122

Ingram, Mr., of Belvoir Castle, on trees struck, 47

Inspection of conductors, 9, 72, 102, 111, 124, 127, 130, 131, 132, 179, 244

Instructions, 63, 99, 176, 181, 240

„ British Army Circular, 70

„ French Official, 59

„ for formation of good earth, 64, 72, 132

Instrument hut at Valencia, how protected, 105

Insulation, shock decreased by, 118

Insulators, 34, 37, 76, 99, 184, 186, 194

„ approved, 13, 118

„ objected to, 8, 11, 13, 14, 16, 21, 24, 68, 69, 73, 86, 89, 103, 111, 118, 126, 139, 186, 226

Iron a better conductor than formerly, 19

„ and copper form best conductors, 119

„ as a conductor, not objected to if galvanised, 19

„ bar, 131, 226

„ „ melted, 61

„ bars on ridge for metallic connection, 125

„ better than copper, 192, 243

„ box for earth contact of conductors, 126

Iron buildings covered with asphalte, 70

„ built ship, metal-rigged, if protected, 122, 200

„ cables, galvanized, sometimes used, 125

„ conductors, 18, 69, 74, 116, 125

„ „ bad, 9, 39, 192

„ „ good, 81, 243

„ „ cost of, 19, 70, 124, 132

„ „ should weigh, 13 to, 37 oz. per foot, 119

„ galvanized for conductor, 74, 116, 132, 139

„ has greater specific heat than copper, 132

„ its high temperature at fusion, 132

„ in coke undergoes no change, 116

„ Joints in defective, 116

„ not to be used for rods, 123

„ points, 88, 138

„ pumps reaching to water act as attractive points, 127

„ rain water pipes, good conductors, 102, 113

„ “reception rod” used in Germany, 125

„ rods on all sides best protection, 124

„ safe in altered position caused damage to building, 127

„ staples and wall eyes, 125, 130

„ terminal rods, 124, 125

„ underground, destruction of prevented, 125

„ wires surrounding copper wire, 200

Isolators (_See_ INSULATORS).

Italy, Lightning rods used there, 179

Jarriant, M., his books abstracted, 111, 115

„ his manufactory, 227

Jenkin, Professor, says point prevents discharge, 106

Jerman, J., his report, 37

Johnson, Clapham & Morris, their answer,13

Johnston, W. P., 181

Joints, avoided in wire cables, 132

„ Cutting & Co., 216

„ damaged, 69, 110, 126

„ how avoided in upper terminals, 23

„ how made, 7, 9, 10, 11, 13, 14, 16, 20, 24, 52, 55, 59, 63, 70, 71, 103, 179, 192, 243

„ must be perfect, 58, 131

„ of bars always defective, 116

„ of extra thickness, 74

„ of rain water pipes, 132

Joints should be metallically continuous, 20

„ soldered, 9, 24, 66, 68, 70, 71, 102, 123, 125, 139, 140, 141, 243

„ to be avoided, 10, 11, 16, 20, 63

Journal of Society of Telegraph Engineers, May, 12, 1875, 130

“Jupiter” ship struck, 62, 95

Karsten, Prof. D. G., lightning conductors, by, 119

Kew, experiments at, on atmospheric electricity, 112

Kilbourne, Lieut., 181

Kirchoff, Prof., on connection with gas mains, 235

Kite, Silk, Franklin’s experiments with, 80

Korte’s, Messrs., Paper, 105

Lacoine, M., on area protected, 134

Lane, T., his Report, 79

Lantern on lighthouse, 184, 186

La Place, M., his Reports, 53, 57

Lateral discharge, 73, 83, 84, 85

Latham, Baldwin, on conductors, 202

Law, E. J., his Report, 37

Laws of Static electricity, 132

Lead a bad conductor, 123

„ at joints, 94, 125

„ casing for upper terminals, 131

„ floors, 188, 189

„ liked because of fitting sharp curves, 123

„ pipe for earth connection, 77

„ roofs and spouts, 51, 82, 102

„ thin sheet of, covering ends of wire, very dangerous, 20

Leaves of trees draw off electricity, 84

Lefevre-Gineau, M., his instructions, 59

Le Gentil, M., his observations, 84

Length and sectional areas, proportion between, 14

„ of conductor above top holdfast destroyed, 193

„ of conductor determines amount of resistance, 131

Lenz, M., on conducting power of metals, 124

Leroy, M., his Report, 51, 53

Lewis, Prof. T. Hayter, Abstracts by, 70, 79, 81, 84, 100, 110, 112, 117, 120, 179

„ his joint Report, 28, 37

Leyden discharges and lightning flashes, 84

„ Jar, 121

Lichtenberg of Gottingen, his opinion, 129

Liddell, J., on lightning conductors, 202

Lighthouses and exposed buildings protected did not suffer, 106

Lighthouse at Berehaven struck by lightning, 208

„ damaged by lightning, 196

„ lightning rods on, 183, 190

Lightning an immense electric spark, 123

„ Ball, 99, 101, 102, 108, 205, 242

„ Bifurcated, 45

„ conductor (_See_ CONDUCTOR).

„ diffused, 108

„ does it pass inside or outside conductor?, 15, 18, 49, 132

„ Flash, 108

„ follows line of least resistance, 108

„ Force of, exemplified, 45

„ Globular (_See supra_ BALL).

„ going to earth without conductor, 128

„ identical with electricity, 82

„ incandescent matter, 100

„ in colliery workings, 237

„ leaves conductor and enters chimney, 203

„ passed down mainmast and through ship, 195

„ passed to iron supports, 128

„ passing out of a ship by a copper bolt, 205

„ Personal safety from, 233

„ protectors (_See_ CONDUCTORS).

„ ran along a bell wire, 195

„ „ thatched roof of house, 128

„ Rod Conference, their Circular, 28

„ Rods (_See_ CONDUCTORS).

„ Sheet, 108

„ the cause of, 81

„ various forms of, 108

Lime, to prevent oxidation of cylinder, 140

Line, conductor should run round building, 134

Linked system of conductors introduced by Sir W. S. Harris, 204

Links of chains, 179

Llandaff Cathedral, conductor on, 102

Lofty buildings require larger rods (_See_ AREA, SECTIONAL).

Long conductors above buildings, their effect, 77

Long’s, F., account of injury to Wells Church, 195

Louvre, New Buildings of the, Special Report for, 64

„ slightly injured by lightning, 123

Low straggling buildings should have several conductors, 15

Lucas, Mr., his Report, 67

Lussac, Gay, M., his Report, 57, 59

McDonald’s, Mr., experience, 193

McGregor, W., protection from Lightning, 106

Magazine, copper doors and windows to, 74, 216

„ of metal, the safest, 73

„ underground, 70

„ well at each end of, 126

(_See also_ POWDER MAGAZINES).

Magne, Mr., his Report, 67

Mahon, Lord, his Report, 79

Mairie, of, 20th Arrondissement struck, 69

Majendie, Major V. D., his Report, 74, 216

Malcolm, Major, R. E., discussion on lightning conductors, 131

Mann, Dr. R. J., Lecture at Society of Arts, 108

„ discussion on earth connections, 131

„ discussion on lightning conductors, 131

Man might touch conductor in thunder storm, 126

Marseilles, Powder Magazine at, how to be protected, 51, 52

Massingham, T., evidence and letter, 15, 16, 17, 193

Masses, metallic must be connected with conductor, 60, 94, 104, 126, 132, 240

Mass or surface, which conducts?, 13, 15, 18, 49, 74, 132, 227

Masts of large vessels, each to have a conductor, 6

Masulipatam, accident near, 206

Materials, inflammable, not ignited, 127

Maxwell, Hugh, on kind of trees struck, 47

Maxwell’s, Clerk, Theory, 109, 126, 132, 133

Mechanical action of lightning, 85

Meiszner’s improvement, 130

Melsens says discharge passes over surface, 132

„ System of protection as applied to monument at Lacken, 230

„ various works by, 124, 138, 140, 141

Men-of-war, old conductors in, 202

Merton College, Oxford, damaged, 126

Metallic cap may assist protection of house, 132

„ circuit, 126

„ connection must be perfect, 130

„ connections on ridge by iron bars, 125

„ joints, 89

Metals, contact of dissimilar, results in decay, 19, 21

Metal cowl of chimney struck, 198

„ for points must be good conductor, 139

„ immaterial if sectional area be large, 131

„ in buildings, contiguity with to be avoided, 5

„ inside or out, to be connected with conductor, 125, 126

„ melted, dimensions of, 61, 83, 223, 231

„ of high conductivity for conductors, 131

„ stays and fastenings, 184, 185

Michel, M., Papers by, 67, 68, 111, 131

„ on galvanised wire rope, 131

Milne, D., his Report, 44

Mining Engineers, Enquiry by, 237

Mohn’s, H., Lynildens Farlighed I Norge, 106

Moist earth destroys terminal, 116

„ for lower terminal, essential, 21, 52, 56, 58, 125, 126

%center%(_See_ EARTH TERMINALS).

Moisture, Access of, to surfaces in contact, 71

Moncel, Comte du, his Report, 67

„ „ his opinions, 226

Monte Video, English Consul’s house struck, 195

Montgolfier, M., his Report, 57

Monument, London, its immunity from injury by lightning, 103

Morea, Signor Lerigi, 180

Müller’s, Prof., conditions for lightning conductors, 129

Müller’s, Dr. Hugo, experiments, 135

Municipal buildings in Paris, lightning rods for, 67, 225

Munson, D., & Co., their rods, 216

Murgatroyd, J., his report, 39

Murray, J., on Atmospheric Electricity, 82

Musgrave, Dr., his report, 79

Myers, Gen., 181

Nails, copper, used in attaching conductor to building, 14 %center%(_See also_ ATTACHMENT).

Nairne, E., his report, 79

Nash lights, 183, 187

National Institute (of France) report made to, 53

Nelson column, 90

Newton, Sir I., machine of glass, 120

“New York,” packet boat, struck, 61, 62

Nickson, Mr., his report, 78

Nottingham, Castle, how protected, 23, 24

Nuts, copper, 192 %center%(_See_ JOINTS).

Number of persons killed by _one_ discharge, 129

Objects on plains attract lightning, 127

Odour, sulphurous, of lightning, 85

Official instructions:

„ Denmark, 176

„ England, 70–74

„ France, 51–69

„ India, 181

„ Italy, 179

„ Norway, 106, 176

„ United States, 181

Ohm, his laws, 18, 133

„ on conducting power of metals, 124

Oldham, Explosion at, 239

Oliver, T., his report, 39

Oxidation, how to be avoided, 83

„ of copper less than that of iron, 131

„ of cylinder, 140

„ „ earth terminals, 131

„ „ surface of conductor unimportant, 73

„ „ terminals leads to failures of conductors, 131

Painted conductor, 69, 94, 99, 103, 113, 117

„ galvanized conductor, 139

Paint objected to, 67, 227

Palais de l’Industrie, Paris, its construction, 61

Paratonnerres, Traité des, 103

„ A Collin et Fils, Paris, 117

„ Nouveau par Jarriant, 111

„ par Jarriant, 115

Partial protection, 194, 244

Passage of electricity of tension in bad conductors, 141

Patterson, Mr., of Philadelphia, on good contact, 58

Payneshill, site of first conductor, 85

Pearson, J. L., his report, 39

Pegwell Bay, tide receded, 48

Pennycook & Co., their answer, 13, 14, 17

Perfect lightning conductor, 131, 186

Perforated iron pipe as earth terminal, 114

Perrott’s, M., experiments, 139

„ remarks on earth contacts, 140

Perry, Prof., on conductors, 132

Personal safety from Lightning, 233

Persons killed by lightning in France, 129

Perspiration from flock of sheep, a conductor, 48

Phillips, R., on atmospherical electricity, 98

Phin, John, on lightning rods, 102, 181

Phipson, R.M., account of destruction of Wells Church, 194

Pidgeon, Mr., discussion on earth connections, 131

Pierron, M., his proposal, 52

Pinnacles on church towers, 10, 29, 137

Pipes, gas, (_See_ GAS, WATER, and EARTH TERMINALS).

„ hard metal, as conductors, 108

„ iron, easily made into protectors, 102

„ of terra cotta, 180

„ rain-water, 34, 74

„ as earth terminal, 114

Plait of copper wire, 5, 9, 205, 210, 215

Planta, Mr., his report, 79

Plate, Earth (_See_ EARTH PLATE).

Platinum points, 37, 115, 140, 227

„ „ approved of, 15, 54, 55, 59, 63, 66, 99, 104, 116, 120

„ „ objected to, 67, 73, 103, 123, 139

„ „ only half the conducting power of copper, 73

„ „ blunted, 69

„ „ fused, 128, 231

Plymouth, Charles Church at, 86

Point Aigrettes (_See infra_ MULTIPLE).

„ attracts electricity, 82

„ blunted, 53, 69

„ breaks the force of lightning, 73

„ coronal (_See infra_ MULTIPLE).

„ dimensions of, 17, 18, 120, 130, 178

„ Duhamel upon, 66

„ Engravings of some modern ones, 230

„ facilitate discharge, 131

Point generally, 9, 17, 18, 76, 79, 81, 86, 92, 122, 125, 131, 139

„ gilded, 9, 55, 59, 71, 120, 138

„ „ needless, 73, 103, 113

„ height of, 52, 138

„ how to be fixed, 14, 52, 53, 55, 58, 130

„ _in situ_, examination of necessary, 18

„ melted, 53, 87, 92, 192, 195, 231

„ multiple, 34, 231

„ „ recommended, 10, 13, 14, 15, 23, 104, 108, 125, 132, 139, 243

„ „ objected to, 18, 71

„ not to be fusible, 93, 120

„ of attraction, 127

„ „ copper, 10, 13, 23, 66, 67, 107, 111, 117, 120, 123, 132, 139

„ „ iron, 88, 138

„ „ brass, 13

„ „ pinnacles to be united to main conductors, 118

„ „ platinum (_See_ PLATINUM).

„ „ silver, 7, 120, 130, 139

„ „ three kinds, 138

„ „ vane, 186 %center%(_See_ VANES).

„ or blunt conductors, 77, 79, 106

„ render lateral discharges less probable, 131

„ Report upon, 60, 66

„ sharp, 129, 130, 132, 138, 139

„ „ not too, 92, 123, 129, 242

„ „ experiments with, 51, 80

„ should be kept clean, 130, 132

„ „ of good conducting metal, 139

„ should it be painted? (_See_ PAINTED).

„ space protected by (_See_ PROTECTION, AREA OF).

„ square tapering, 23

„ used in Germany, fire gilded copper cone or sphere, 105, 111, 130

„ useful, 102, 122

„ useless, 77, 103, 113

„ vertical, horizontal, or perpendicular, 58

Poisson, M., his joint instructions, 59

Polarity of ship’s compass reversed by lightning, 121

Poles, Telegraphic, how protected, 101

Pouillet, M., his joint Report, 60, 66

„ on Conducting Powers of Metals, 124

„ „ Discharge of Lightning, 131

Powder magazines, 51, 52, 55, 56, 57, 66, 67, 70, 73, 74, 76, 81, 87, 109, 118, 123, 126, 130, 177, 178, 216

Preece’s, Mr. W. H., Abstract of Replies of Manufacturers, 22

„ Discussion on Lightning Conductors, 131

„ Discussion on Earth Connection, 131

„ Abstracts by, 98, 102, 117, 130, 132, 241, 243

„ on Conductors, 100

„ „ Ball Lightning, 101, 102

„ Paper Discussion on, 102

„ Proper Form of Lightning Conductors, 132

„ Space protected, 135

Priestly, Dr., his Report, 79

Pringle, Sir John, his Report, 79

„ advocated use of points, 122

Protector (_See_ CONDUCTOR).

Protection, Area of, 6, 9, 13, 15, 16, 21, 22, 24, 57, 60, 64, 67, 71, 73, 82, 87, 96, 102, 106, 111, 112, 117, 123, 125, 134, 135, 137, 180, 192, 226, 230, 243

„ of buildings from lightning, 195

„ „ buildings from lightning, R. S. Brough, 132

„ „ iron from decay by galvanizing, 132

„ „ telegraph wires by lightning conductor, 130

„ partial, 194, 244

Prussia, accidents from lightning, 126

Purfleet, Board House struck, 76, 78, 88, 122, 126

Purity of copper essential, 124

Quadrangular iron bar for conductor (_See_ IRON, BAR OF).

Questions respecting damage by lightning, 28, 29

Radius of Protection (_See_ PROTECTION, AREA OF).

Railings to be joined to conductor, 125

Railway Terminus at Antwerp struck, 137

„ track makes capital earth, 117

Rain-water pipe as conductor, 37, 38, 41, 132, 213

Rat, Wet, indestructible by electricity, 85

Ravel, M. de Puy Contal, his proposal, 52

“Reception rod” of iron used in Germany, 125

Regnault, M., his reports, 66

Regnier’s system of lightning rods, 54, 57

Regulations for lightning conductors in Denmark, 176

Repellers, Glass, 186

Resistance of conductor varies with its length (_See_ AREA, SECTIONAL). Retarding influence of electrostatic capacity, 133

Return shock mechanical in effect, 129

Ribbons and tubes still in use, 133

„ or rods offer less resistance than ropes, 204

%center%(_See also_ TAPE.)

Richard & Co., their tall chimney struck, 44

Richmann, Prof., killed, 1753, whilst experimenting, 121

Ridges, metallic conductor covering, 68, 177

Rittenhouse, Dr., of Philadelphia, his observations, 53

Rivets, copper, used for joints, 24

Robins, E. C., his report, 39

Robertson, J., his report, 76

Rochon, M., his report, 51, 57

Rods better than ropes or chains, 96, 204

„ solid copper, 10, 13, 14, 15, 73, 89, 117, 123, 184, 195

„ copper not fusible, 125

„ copper, their size, 70, 180

„ Earth terminals of (_which see_).

„ elevation, how coupled, 24

„ horizontal, on roof, 52, 118

„ how to be fastened to buildings, (_See_ ATTACHMENT).

„ iron, conductor, 10, 46, 47, 77, 99, 117, 177

„ „ tarred or galvanized, 104

„ „ the size of, 52, 58, 70, 74, 130

„ Joints in (_See_ JOINTS).

„ Lightning, and how to construct them, 102

„ Munson’s, 216

„ must be thoroughly joined, 52

„ not to be inside chimney, 111

„ of greatest length gives most protection, 137

„ of spirally twisted iron, 192

„ Points of (_See_ POINTS).

„ should be painted (_See_ PAINTED).

Rods, size of (_See_ CONDUCTOR, Size of).

„ Tie, must be connected with conductor, 60

„ to be diameter of chimney above top, 111

„ to be made of conical form, 129

„ will not divert electric fire from its path, 125

Rome, system of rods used there, 179

Roof, all metals in, to be connected, 60, 72

„ covered with metal, 37, 69, 177

„ lead, easily made into protector, 102

„ of wood or slate has conductor on ridge, 125

„ with masses of metal, difficult to protect, 7

Rope better than rod, 5, 10, 60, 111, 113, 131, 243

„ brass wire, 60, 124

„ conductor, how to fit to ship’s rigging, 6

„ „ lower end of to be opened, 11, 15

„ copper and zinc wire decayed, 205

„ copper better than iron for towns, 19

„ copper, its advantages and disadvantages, 8, 56, 63, 131, 134

„ copper wire, 10, 13, 14, 34, 37, 39, 60, 75, 103, 125, 131, 225, 226, 227

„ „ dimensions of, 8, 9, 223

„ „ has both surface and mass, 16

„ „ too expensive, 58

„ easily bent without angles, 19 „ „ joined, diverted, or lengthened, 19

„ hemp, for conductors, 56

„ Iron wire, 19, 58, 68, 125, 227, 243

„ „ „ smashed, 86

„ liable to corrosion on factory chimneys, 125

„ of thick copper wire, 226, 229

„ or cable, fringed out at upper terminal, 14

„ metallic, disadvantages of, 62, 63, 95, 204

„ for connecting points with metal bars, 55

„ with hemp strand in middle, 116, 227

„ Wire, conductor, badly erected, 39

„ damaged, 193

Rosherville Church struck though provided with a conductor, 34

Rounded and pointed conductors, 79 %center%(_See_ POINT.)

Route to earth for conductor, 126

Royal Society, Committee of, 76, 78, 79

Rules for erecting Conductors %center%(_See_ INSTRUCTIONS).

Russell, F. & Co., their answers, 9, 17

Rust increases electrical resistance, 70, 107

Sacré’s, M. E., system, 140

Safety from Lightning, Personal, 233

St. Ann’s Hotel, Buxton, struck, 34

St. Aubyn, J. P., 29

St. Clotilde Church, Paris, struck, 69

St. Eloi Church, Paris, struck, 69

St. George’s, Leicester, 126, 240

St. James’ Church, West-End, Hants, struck, 34

St. Mary’s, Crumpsall, near Manchester, struck, 39

St. Mark’s, Venice, 103

St. Matthias’s Church, Brixton, struck, 39

St. Michael’s Church, Stamford, struck, 43

St. Paul’s Cathedral, Accident to, 78

„ „ fitted with copper wire rope, 131

„ „ its immunity from injury by lightning, 103

St. Peter’s Church, Brighton, pinnacle struck, 48

St. Sepulchre’s Church, Northampton, struck, 37

St. Sulpice Church, Paris, struck, 69

Sanderson & Co., their answers, 23, 24

“Scientific American,” 118

Screen, metallic, a protection, 85

Secchi, P., 180

Sectional Area (_See_ AREA, SECTIONAL).

Sharp Points (_See_ POINTS).

Sheets, Iron, struck, 53

Sheet lightning is the reflection of forked, 101, 242

Ships struck, 53, 61, 62, 88, 95, 195, 205

„ conductors, 6, 90, 121, 122, 195, 199, 200

Short terminal points to chimneys, 125

Siemens, A., abstract by, 127

Silver Points (_See_ POINTS OF SILVER).

Simmons, J., his Essay, 81

Size of conductor (_See_ CONDUCTOR, SIZE OF). Small conductor replaced by heavier one, 194

Smoke discharged from chimney a conductor, 132

Smoke often destroys brass, 124

Snell, H. S., his report, 39

Soil, change in nature of, its effect, 71

„ dry, a non-conductor, 70

„ metallic veins beneath, 61

„ water beneath will attract lightning, 61

Soldered joints (_See_ JOINTS).

Solder, objectionable, 16

„ the use of, imperative, 20

„ „ not universal, 20

„ with copper, 103

Solid rods superseded by ropes of wire (_See_ ROPES), 131

South Foreland Lighthouse, 185, 186

Spagnoletti, Mr., discussion on lightning conductors, 131

Spang, H. W., Treatise on Lightning Conductors, 112, 181

Sparks from Holtz’s machine, 141

„ „ Ruhmkorff’s coil, 141

Space protected (_See_ PROTECTION, AREA OF).

Specific attraction, equal in all bodies, 73

„ heat of iron greater than copper, 132

Sphere, Metal, on top of conductors, 111

Spike of iron (_See_ POINT).

Spiral twisted iron rods, 192

Spires, Church, conductor for, how fixed, 23

Spire, Church, conductors for without joints, 24

Spires, connection from bottom of vane rod, 14

Spout, Iron, entered by lightning, 43

Spout split at joints, 45, 46, 47, 49

Spratt’s patent conductors, 205, 210, 215

Spurn Point High Light, 184

Square building to have terminal at each end, 125

„ wire, 13, 216

Staples for attaching conductor (_See_ ATTACHMENT).

Static discharges from conductors, 133

„ electricity, laws of, 132

Stays, Metal, 184,185

Steeple of Jacobi Church, at Hamburg, 129

Steeples to have horizontal conductors, 113, 125

Steeple with lightning rod injured, 124, 125

Steinheil’s lightning protector, 130

Sterriker, John, his report, 45, 46

Straps and nails (_See_ ATTACHMENT).

Strasbourg, accident at, 99

Straw conductors for country use, 104

Strata, water bearing, connection to be made with (_See_ EARTH TERMINAL).

Stream of fire in rigging of ship, 54

Striking distance, 650 to, 6500 feet, 108

Stroke, lightning, 9 or, 10 miles, 108

Sullivan, Adml. 183, 195, 199

Sulphur Paste made of galena and melted, for end of conductor, 58

Sulphurous fumes destructive to terminals, 131

„ odour of lightning, 85

Sun burner to lofty building, 201

Superficial conductors, advantages of, 86

Supports of protector soldered with zinc, 140

Supposed perfect conductor, 131

Surface exposed to air considerable, 139

„ or mass, which conducts?, 13, 15, 18, 49, 74, 89, 132

Swan Cotton Mill, 239

Sweden, accidents from lightning, 126

Symons, G. J., 43, 46, 183

„ abstracts by, 74, 89, 99, 102, 104, 111, 115, 131, 132, 134, 135

Tacchini, Prof., 179, 180

Tait, Prof., on thunderstorms, 241

Tanks, 15, 71, 94, 107, 130

Tape, joints, if any, should be rivetted and soldered, 7

„ copper better than rope, 8, 204

„ „ objections to, 5, 6, 16

„ „ let into masts, 92

„ lower end to have a discharging fork, 11

„ Phin, upon, 103

„ to be cut in strips for earth terminal, 15, 23

„ copper, the sizes and lengths made, 7, 10, 14, 23, 70, 133

„ cheaper than rope, 8, 9

Tarred casing of wood to enclose iron, 125

„ metallic rope, 60

Taunton Church, large copper rope conductor, 8

Teale, F. G., of Calcutta, 181

Telegraph instruments injured, 100

„ poles, how protected, 101

„ wires affected underground, 101

Temperature, variations of, affecting length of conductor, 68, 125, 226

Terkelsen, C., abstract by, 106

Terminal area protected by (_See_ PROTECTION, AREA OF).

Terminals (_See_ POINTS).

Terminal, earth (_See_ EARTH TERMINAL).

Terminal for every, 20 ft. of roof, 125

„ how fastened to roof, 52

„ if numerous, should have proportionately thicker conductor (_See_ AREA, SECTIONAL).

„ long upper, 68, 77, 225, 229

„ jar roof by vibration by wind, 116, 127

„ not always pointed, 92, 125

„ painted or tinned, 55

„ rods, 17, 55, 66, 67, 72, 124

„ „ to branch out at top %center%(_See_ POINTS).

„ Upper, how attached to conductor, 60

„ „ fused, 193

„ „ should be cased in lead to protect from sulphurous fumes, 131

„ „ to be a round rod, 125

„ „ to be iron or copper, 82

„ „ too small, 62

„ „ what it is, 59

„ „ what made of, 13

Terra Cotta water pipes, 180

Testing apparatus, 111, 225, 228, 243, 244

„ of building as well as of conductor, 9

„ of conductors with galvanometer, 9, 131

„ to be periodical, 132, 244

Theory of protection (_See_ PROTECTION, AREA OF).

Thimbles, glass, 186

Thomson, Prof. Sir W., on conductors, 47, 48, 49, 102, 133

Thunderstorms dangerous where no woods are, 119

„ in France, 1822, 123

„ nature of, 85

Ties, Metallic (_See_ ATTACHMENT).

Tin and lead conductors tried, 123

Tinfoil, experiments with, 199

Tinned metallic wire, 95

Tips (_See_ POINTS).

Tomes, J., F.R.S,, accident to his house, 210

Top conductor (_See_ CONDUCTOR RIDGE).

Torquay, no good earth there, 130

Tower of church struck, 29

„ of house struck, 37

Trees bad conductors, 127

Trees, High, their protective action, 85, 127, 243

„ injured while passing lightning to better conductor, 127

„ on plains attract lightning, 127

„ struck, 45, 47, 49

Trenches, Connections in, 72

„ filled with carbonaceous materials, 7, 12, 100, 125

„ in rocky or dry soil, 72 (_See also_ EARTH TERMINALS).

Trough, Oaken, for lower terminals to pass through, 56

Trinity House, 183

Tube conductor for Houses of Parliament, 199

„ Copper, 7, 10, 14, 70, 74, 133

„ „ having copper cable passing through it, 13

„ patent insertion joints, 7

„ Iron, 86, 117

„ conductors, why objectionable, 5

Turrets, conductors for, how fixed, 23, 24

Twyford Moors, near Winchester, 34

Underground connection (_See_ EARTH TERMINAL).

United States, accidents from lightning, 126

University Coll., Chimney struck, 38

University of Padua protected by conductors, 122

Upper terminal (_See_ TERMINAL UPPER and POINTS).

Upwood Gorse, Caterham, accident at, 210

Vaillant, Le Maréchal, his Report, 66

Vanes, how connected, &c., 10, 11, 14, 23, 39, 40, 52, 53, 104, 183, 185, 186, 202

Varley, C., quoted, 101

Venetians decreed to use lightning rods in Republic, 122

Ventilating pipes, 216

Vitreous tubes (Fulgurites) formed by electricity, 112

Vyle’s, S., rod & testing apparatus, 244

Walker, C. V., on conductors, 84

„ on Leyden discharges, 84

„ J., 187

„ Matthew, His knot, 16

Wall eyes of iron, 130

%center%(_See also_ ATTACHMENT).

Wandsworth, chimney of house struck, 38

Ward, G. G., of New York, 181

Water mains and underground water generally (_See_ EARTH TERMINALS).

Water spouts to be connected, 10, 226

Watson’s, Dr., conductor at Payneshill, 85

„ „ for ships, 121

„ report, 76, 79

Weathercock (_See_ VANES).

Weber, Dr. L., on lightning discharges in Schleswig Holstein, 127, 231

Week, St. Mary, the Church of, 29, 30

Weight of conductors (_See_ CONDUCTORS, SIZE OF).

Wells (_See_ EARTH TERMINALS).

Wells Church, Norfolk, destruction of, by lightning, 194

West side of house, rod to be on, 100

Wheatstone quoted, on fusion of rod, 83

Whichcord, J., his joint Report, 28

White, W. H., Secretary R.I.B.A., circular signed by him, 28

Wilkins & Weatherby, their answer, 4–6, 17

Wilson, Mr., his report and views, 76, 79

Wilson, R., on conductors on chimneys, 110

Wind, action of on conductors, 116, 127

Windmill with conductor struck, 128

Windows, copper, to magazines, 74

Winkler, Prof. J. H. (1746), electricity cause of thunderstorm, 129

Wire cables (_See_ ROPE).

„ cage as protection without use of earth, 132

„ melted into drops like shot, 195

„ of zinc melted, 107

„ rusted in earth and was useless, 107

„ square, 13, 216

Withers, J. B. M., his report, 40

Wood to be creosoted to form case for iron, 125

„ coated with resin, as a conductor, 54

Workhouse, how to be protected, 10

Wrexham Church struck, 126

Wrottesley, Col. G., R.E., his report, 40

Wrought iron (_See_ IRON).

Wyatt Papworth Church struck, 39

York, accident at, 219

Zenger’s, Prof. C., Symmetrische Blitzableiter, 104

Zinc better conductor than iron, 74

„ coating, 72

„ chimney of house struck, 37

„ cylinder, wire to pass through, 83

„ strips, 192

„ wire melted, 107

TRANSCRIBER’S NOTES

1. P. 170, changed “Annals of Electricity. 10 vols. 8vo. 18363–4” to “Annals of Electricity. 10 vols. 8vo. 1836”. 2. Silently corrected typographical errors and also variations in spelling. 3. Retained anachronistic, non-standard, and uncertain spellings as printed. 4. Enclosed italics font in _underscores_. 5. Enclosed bold font in =equals=. 6. Enclosed small font in ¤currency signs¤. 7. Superscripts are denoted by a caret before a single superscript character or a series of superscripted characters enclosed in curly braces, e.g. M^r. or M^{ister}. 8. Subscripts are denoted by an underscore before a series of subscripted characters enclosed in curly braces, e.g. H_{2}O.