Part 4

=Destruction of Ships at Sea.=--The destructive effects of lightning on ships at sea, before the general adoption of lightning conductors, seems almost incredible at the present day. From official records it appears that the damage done to the Royal Navy of England alone involved an expenditure of from £6,000 to £10,000 a year. We are told by Sir William Snow Harris, who devoted himself for many years to this subject with extraordinary zeal and complete success, that between the year 1810 and the year 1815--that is, within a period of five years--“no less than forty sail of the line, twenty frigates, and twelve sloops and corvettes were placed _hors de combat_ by lightning. In the merchant navy, within a comparatively small number of years, no less than thirty-four ships, most of them large vessels with rich cargoes, have been totally destroyed--been either burned or sunk--to say nothing of a host of vessels partially destroyed or severely damaged.”[20]

And these statements, be it observed, take no account of ships that were simply reported as missing, some of which, we can hardly doubt, were struck by lightning in the open sea, and went down with all hands on board. A famous ship of forty-four guns, the _Resistance_, was struck by lightning in the Straits of Malacca, and the powder magazine exploding, she went to the bottom. Of her whole crew only three were saved, who happened to be picked up by a passing boat. It has been well observed that, were it not for these three chance survivors, nothing would have been known concerning the fate of the vessel, and she would have been simply recorded as missing in the Admiralty lists.

Nothing is more fearful to contemplate than the scene on board a ship when she is struck by lightning in the open sea, with the winds howling around, the waves rolling mountains high, the rain coming down in torrents, and the vivid flashes lighting up the gloom at intervals, and carrying death and destruction in their track. I will read you one or two brief accounts of such a scene, given in the pithy but expressive language of the sailor. In January, 1786, the _Thisbe_, of thirty-six guns, was struck by lightning off the coast of Scilly, and reduced to the condition of a wreck. Here is an extract from the ship’s log: “Four A. M., strong gales; handed mainsail and main top-sail; hove to with storm staysails; blowing very heavy, S. E. 4.15, a flash of lightning, with tremendous thunder, disabled some of our people. A second flash set the mainsail, main-top, and mizen staysails on fire. Obliged to cut away the mainmast; this carried away mizen top-mast and fore top-sail yard. Found foremast also shivered by the lightning. Fore top-mast went over the side about 9 A. M. Set the foresail.”[21]

A few years later, in March, 1796, the _Lowestoffe_ was struck in the Mediterranean, and we read as follows in the log of the ship: “North end of Minorca; heavy squalls; hail, rain, thunder, and lightning. 12.15, ship struck by lightning, which knocked three men from the masthead, one killed. 12.30, ship again struck; main top-mast shivered in pieces; many men struck senseless on the decks. Ship again struck, and set on fire in the masts and rigging; mainmast shivered in pieces; fore top-mast shivered; men benumbed on the decks, and knocked out of the top; one man killed on the spot. 1.30, cut away the mainmast; employed clearing wreck. 4, moderate; set the foresail.”[22]

Again, in 1810, the _Repulse_, a ship of seventy-four guns, was struck, off the coast of Spain. “The wind had been variable in the morning--and at 12.35 there was a heavy squall, with rain, thunder, and lightning. The ship was struck by two vivid flashes of lightning, which shivered the maintop-gallant mast, and severely damaged the mainmast. Seven men were killed on the spot; three others only survived a few days; and ten others were maimed for life. After the second discharge the rain fell in torrents. The ship was more completely crippled than if she had been in action, and the squadron, then engaged on a critical service, lost for a time one of its fastest and best ships.”[23]

=Destruction of Powder Magazines.=--Not less appalling is the devastation caused by lightning when it falls on a powder magazine. Here is a striking example: On the eighteenth of August, 1769, the tower of St. Nazaire, at Brescia, was struck by lightning. Underneath the tower about 200,000 pounds of gunpowder, belonging to the Republic of Venice, were stored in vaults. The powder exploded, leveling to the ground a great part of the beautiful city of Brescia, and burying thousands of its inhabitants in the ruins. It is said that the tower itself was blown up bodily to a great height in the air, and came down in a shower of stones. This is, perhaps, the most fearful disaster of the kind on record. But we are not without examples in our own times. In the year 1856 the lightning fell on the Church of St. John, in the Island of Rhodes. A large quantity of gunpowder had been deposited in the vaults of the church. This was ignited by the flash; the building was reduced to a mass of ruins, a large portion of the town was destroyed, and a considerable number of the inhabitants were killed. Again, in the following year, the magazine of Joudpore, in the Bombay Presidency, was struck by lightning. Many thousand pounds of gunpowder were blown up, five hundred houses were destroyed, and nearly a thousand people are said to have been killed.[24]

=Experimental Illustrations.=--And now, before proceeding further, I will make one or two experiments, with a view of showing that the electricity of our machines is capable of producing effects similar to those produced by lightning, though immeasurably inferior in point of magnitude. Here is a common tumbler, about three-quarters full of water. Into it I introduce two bent rods of brass, which are carefully insulated below the surface of the water by a covering of india-rubber. The points, however, are exposed, and come to within an inch of one another, near the bottom of the tumbler. Outside the tumbler, the brass rods are mounted on a stand, by means of which I can send the full charge of this Leyden jar battery through the water, from point to point. Since water is a bad conductor of electricity, as compared with metals, the charge encounters great resistance in passing through it, and in overcoming this resistance produces considerable mechanical commotion, which is usually sufficient to shiver the glass to pieces.

To charge the battery will take about twenty turns of this large Holtz machine. Observe how the pith ball of the electroscope rises as the machine is worked, showing that the charge is going in. And now it remains stationary; which is a sign that the battery is fully charged, and can receive no more. You will notice that the outside coating of the battery has been already connected with one of the brass rods dipping into the tumbler of water. By means of this discharger I will now bring the inside coating into connection with the other rod. And see, before contact is actually made, the spark has leaped across, and our tumbler is violently burst asunder from top to bottom.

This will probably appear to you a very small affair, when compared with the tearing asunder of solid masonry, and the hurling about of stones by the ton weight. No doubt it is; and that is just one of the lessons we have to learn from the experiment we have made. For, not only does it show us that effects of this kind may be caused by electricity artificially produced, but it brings home forcibly to the mind how incomparably more powerful is the lightning of the clouds than the electricity of our machines.

The property which electricity has of setting fire to combustible substances may be easily illustrated. This india-rubber tube is connected with the gas pipe under the floor, and to the end of the tube is fitted a brass stop-cock which I hold in my hand. I open the cock, and allow the jet of gas to flow toward the conductor of Carré’s machine, while my assistant turns the handle; a spark passes, and the gas is lit. Again, my assistant stands on this insulating stool, placing his hand on the large conductor of the machine, while I turn the handle. His body becomes electrified, and when he presents his knuckle to this vessel of spirits of wine, which is electrically connected with the earth, a spark leaps across, and the spirits of wine are at once in a blaze. Once more; I tie a little gun-cotton around one knob of the discharging rod, and then use it to discharge a small Leyden jar; at the moment of the discharge the gun-cotton is set on fire.

It would be easy to explode gunpowder with the electric spark, but the smoke of the explosion would make the lecture-hall very unpleasant for the remainder of the lecture. I propose, therefore, to substitute for gunpowder an explosive mixture of oxygen and hydrogen, with which I have filled this little metal flask, commonly known as Volta’s pistol. By a very simple contrivance, the electric spark is discharged through the mixture, when I hold the flask toward the conductor of the machine. A cork is fitted tightly into the neck of the flask, and at the moment the spark passes you hear a loud explosion, and you see the cork driven violently up to the ceiling.

=Destruction of Life.=--The last effect of lightning to which I shall refer, and which, perhaps, more than any other, strikes us with terror, is the sudden and utter extinction of life, when the lightning flash descends on man or on beast. So swift is this effect, in most cases, that death is, in all probability, absolutely painless, and the victim is dead before he can feel that he is struck. I cannot give you, with any degree of exactness, the number of people killed every year by lightning, because the record of such deaths has been hitherto very imperfectly kept, in almost all countries, and is, beyond doubt, very incomplete. But perhaps you will be surprised to learn that the number of deaths by lightning actually recorded is, on an average, in England about 22 every year, in France 80, in Prussia 110, in Austria 212, in European Russia 440.[25]

So far as can be gathered from the existing sources of information, it would seem that the number of persons killed by lightning is, on the whole, about one in three of those who are struck. The rest are sometimes only stunned, sometimes more or less burned, sometimes made deaf for a time, sometimes partially paralyzed. On particular occasions, however, especially when the lightning falls on a large assembly of people, the number of persons struck down and slightly injured, in proportion to the number killed, is very much increased.

An interesting case of this kind is reported by Mr. Tomlinson. “On the twenty-ninth of August, 1847, at the parish church of Welton, Lincolnshire, while the congregation were engaged in singing the hymn before the sermon, and the Rev. Mr. Williamson had just ascended the pulpit, the lightning was seen to enter the church from the belfry, and instantly an explosion occurred in the centre of the edifice. All that could move made for the door, and Mr. Williamson descended from the pulpit, endeavoring to allay the fears of the people. But attention was now called to the fact that several of the congregation were lying in different parts of the church, apparently dead, some of whom had their clothing on fire. Five women were found injured, and having their faces blackened and burned, and a boy had his clothes almost entirely consumed. A respected old parishioner, Mr. Brownlow, aged sixty-eight, was discovered lying at the bottom of his pew, immediately beneath one of the chandeliers, quite dead. There were no marks on the body, but the buttons of his waistcoat were melted, the right leg of his trousers torn down, and his coat literally burnt off. His wife in the same pew received no injury.”[26]

Not less striking is the story told by Dr. Plummer, surgeon of the Illinois Volunteers, in the _Medical and Surgical Reporter_ of June 19, 1865: “Our regiment was yesterday the scene of one of the most terrible calamities which it has been my lot to witness. About two o’clock a violent thunderstorm visited us. While the old guard was being turned out to receive the new, a blinding flash of lightning was seen, accompanied instantly by a terrific peal of thunder. The whole of the old guard, together with part of the new, were thrown violently to the earth. The shock was so severe and sudden that, in most cases, the rear rank men were thrown across the front rank men. One man was instantly killed, and thirty-two men were more or less severely burned by the electric fluid. In some instances the men’s boots and shoes were rent from their feet and torn to pieces, and, strange as it may appear, the men were injured but little in the feet. In all cases the burns appear as if they had been caused by scalding-hot water, in many instances the skin being shriveled and torn off. The men all seem to be doing well, and a part of them will be able to resume their duties in a few days.”

=The Return Shock.=--It sometimes happens that people are struck down and even killed at the moment a discharge of lightning takes place between a cloud and the earth, though they are very far from the point where the flash is actually seen to pass; while others, who are situated between them and the lightning, suffer very little, or perhaps not at all. This curious phenomenon was first carefully investigated by Lord Mahon in the year 1779, and was called by him the “return shock.” His theory, which is now commonly accepted, may be easily understood with the aid of the sketch before you.

Let us suppose ABC to represent the outline of a thundercloud which dips down toward the earth at A and at C. The electricity of the cloud develops by inductive action a charge of the opposite kind in the earth beneath it. But the inductive action is most powerful at E and F, where the cloud comes nearest to the earth. Hence, bodies situated near these points may be very highly electrified as compared with bodies at a point between them, such as D. Now, when a flash of lightning passes at E, the under part of the cloud is at once relieved of its electricity, its inductive action ceases, and, therefore, a person situated at F suddenly ceases to be electrified. This sudden change from a highly electrified to a neutral state involves a shock to his system which may be severe enough to stun or even to kill him. Meanwhile, people at _D_, having been also electrified to some extent by the influence of the thundercloud, must in like manner undergo a change in their electrical condition when the flash of lightning passes, but this change will be less violent because they were less highly electrified.

Many experiments have been devised to illustrate this theory of Lord Mahon. But the best illustration I know is furnished by this electric machine of Carré’s. If you stand near one end of the large conductor when the machine is in action and sparks are taken from the other end, you will feel a distinct electric shock every time a spark passes. The large conductor here takes the place of the cloud, the spark that passes at one end represents the flash of lightning, and the observer at the other end gets the return shock, though he is at a considerable distance from the point where the flash is seen.

An experiment of this kind, of course, cannot be made sensible to a large audience like the present. But I can give you a good idea of the effect by means of this tuft of colored papers. While the machine is in action I hold the tuft of papers near that end of the conductor which is farthest from the point where the discharge takes place. You see the paper ribbons are electrified by induction, and, in virtue of mutual repulsion, stand out from one another “like quills upon the fretful porcupine.” But, when a spark passes, the inductive action ceases, the paper ribbons cease to be electrified, and the whole tuft suddenly collapses into its normal state.

While fully accepting Lord Mahon’s theory of the return shock as perfectly good so far as it goes, I would venture to point out another influence which must often contribute largely to produce the effect in question, and which is not dependent on the form of the cloud. It may easily happen, from the nature of the surface in the district affected by a thundercloud, that the point of most intense electrification--say E in the figure--is in good electrical communication with a distant point, such as F, while it is very imperfectly connected with a much nearer point, D. In such a case it is evident that bodies at F will share largely in the highly-electrified condition of E, and also share largely in the sudden change of that condition the moment the flash of lightning passes; whereas bodies at D will be less highly electrified before the discharge, and less violently disturbed when the discharge takes place.

This principle may be illustrated by a very simple experiment. Here is a brass chain about twenty feet long. One end of it I hand to any one among the audience who will kindly take hold of it; the other end I hold in my hand. I now stand near the conductor of the machine; and will ask some one to stand about ten feet away from me, near the middle of the chain, but without touching it. Now observe what happens when the machine is worked and I take a spark from the conductor: My friend at the far end of the chain, twenty feet away, gets a shock nearly as severe as the one I get myself, because he is in good electrical communication with the point where the discharge takes place. But my more fortunate friend, who is ten feet nearer to the flash, is hardly sensible of any effect, because he is connected with me only through the floor of the hall, which is, comparatively speaking, a bad conductor of electricity.

=Summary.=--Let me now briefly sum up the chief destructive effects of lightning. First, with regard to good conductors: though it passes harmlessly through them if they be large enough to afford it an easy passage, it melts and converts them into vapor if they be of such small dimensions as to offer considerable resistance. Secondly, lightning acts with great mechanical force on bad conductors; it is capable of tearing asunder large masses of masonry, and of projecting the fragments to a considerable distance. Thirdly, it sets fire to combustible materials. And lastly, it causes the instantaneous death of men and animals.

=Franklin’s Lightning Rods.=--The object of lightning conductors is to protect life and property from these destructive effects. Their use was first suggested by Franklin, in 1749, even before his famous experiment with the kite; and immediately after that experiment, in 1752, he set up, on his own house, in Philadelphia, the first lightning conductor ever made. He even devised an ingenious contrivance, by means of which he received notice when a thundercloud was approaching. The contrivance consisted of a peal of bells, which he hung on his lightning conductor, and which were set ringing whenever the lightning conductor became charged with electricity.

Franklin’s lightning rods were soon adopted in America; and he himself contributed very much to their popularity by the simple and lucid instructions he issued every year, for the benefit of his countrymen, in the annual publication known as “Poor Richard’s Almanac.” It is very interesting at this distance of time to read the homely practical rules laid down by this great philosopher and statesman; and, though some modifications have been suggested by the experience of a hundred and thirty years, especially as regards the dimensions of the lightning conductor, it is surprising to find how accurately the general principles of its construction, and of its action, are here set forth.

“It has pleased God,” he says, “in His goodness to mankind, at length to discover to them the means of securing their habitations and other buildings from mischief by thunder and lightning. The method is this: Provide a small iron rod, which may be made of the rod-iron used by nailors, but of such a length that one end being three or four feet in the moist ground, the other may be six or eight feet above the highest part of the building. To the upper end of the rod fasten about a foot of brass wire, the size of a common knitting needle, sharpened to a fine point; the rod may be secured on the house by a few small staples. If the house or barn be long, there may be a rod and point at each end, and a middling wire along the ridge from one to the other. A house thus furnished will not be damaged by lightning, it being attracted by the points and passing through the metal into the ground, without hurting anything. Vessels also having a sharp-pointed rod fixed on the top of their masts, with a wire from the foot of the rod reaching down round one of the shrouds to the water, will not be hurt by lightning.”

=Introduction of Lightning Rods into England.=--The progress of lightning conductors was more slow in England and on the Continent of Europe, owing to a fear, not unnatural, that they might, in some cases, draw down the lightning where it would not otherwise have fallen. People preferred to take their chance of escaping as they had escaped before, rather than invite, as it were, the lightning to descend on their houses, in the hope that an iron rod would convey it harmless to the earth. But the immense amount of damage done every year by lightning, soon led practical men to entertain a proposal which offered complete immunity from all danger on such easy terms; and when it was found that buildings protected by lightning conductors were, over and over again, struck by lightning without suffering any harm, a general conviction of their utility was gradually established in the public mind.

The first public building protected by a lightning rod in England was St. Paul’s Cathedral, in London. On the eighteenth of June, 1764, the beautiful steeple of Saint Bride’s Church, in the city, was struck by lightning and reduced to ruin. This incident awakened the attention of the dean and chapter of St. Paul’s to the danger of a similar calamity, which seemed, as it were, impending over their own church. After long deliberation, they referred the matter to the Royal Society, asking for advice and instruction. A committee of scientific men was appointed by the Royal Society to consider the question. Benjamin Franklin himself, who happened to be in London at the time, as the representative of the American States in their dispute with England, was nominated a member of the committee. And the result of its deliberation was that, in the year 1769, a number of lightning conductors were erected on St. Paul’s Cathedral.