Chapter 2

In our description we have only given the main features of the invention, the inventor having mentioned to us, in confidence, several improvements designed to perfect the details of his invention, among which we may mention the steering arrangement and arrangements for attacking a vessel provided with what our contemporary, _Engineering_, not inaptly terms a "crinoline," _i. e._, a network for keeping off torpedoes. The transverse dimensions of our engravings have been considerably augmented for the sake of clearness.--_Mech. World._

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DUPUY DE LOME.

M. Dupuy De Lome died on the 1st Feb., 1885, at the age of 68. It may be questioned whether any constructor has ever rendered greater services to the navy of any country than those rendered by M. Dupuy to the French Navy during the thirty years 1840-70. Since the fall of the Empire his connection with the naval service has been terminated, but his professional and scientific standing has been fully maintained, and his energies have found scope in the conduct of the great and growing business of the _Forges et Chantiers_ Company. In him France has undoubtedly lost her greatest naval architect.

The son of a naval officer, M. Dupuy was born in October, 1816, near L'Orient, and entered _L'Ecole Polytechnique_ when nineteen years of age. In that famous establishment he received the thorough preliminary training which France has so long and wisely provided for those who are to become the designers of her war-ships. After finishing his professional education, he came to England about 1842, and made a thorough study of iron shipbuilding and steam navigation, in both of which we then held a long lead of France. His report, subsequently published under the title of "Memoire sur la Construction des Batiments en Fer"--Paris, 1844--is probably the best account given to the world of the state of iron shipbuilding forty years ago: and its perusal not merely enables one to gauge the progress since made, but to form an estimate of the great ability and clear style of the writer. We may assume that this visit to England, coming after the thorough education received in Francem did much toward forming the views to which expression was soon given in designs and reports on new types of war ships.

When the young constructor settled down to his work in the arsenal at Toulon, on his return from England, the only armed steamships in the French Navy were propelled by paddle-wheels, and there was great opposition to the introduction of steam power into line-of-battle ships. The paddle-wheel was seen to be unsuited to such large fighting vessels, and there was no confidence in the screw; while the great majority of naval officers in France, as well as in England, were averse to any decrease in sail spread. M. Dupuy had carefully studied the details of the Great Britain, which he had seen building at Bristol, and was convinced that full steam power should be given to line-of-battle ships. He grasped and held fast to this fundamental idea; and as early as the year 1845 he addressed a remarkable report to the Minister of Marine, suggesting the construction of a full-powered screw frigate, to be built with an iron hull, and protected by a belt of armor formed by several thicknesses of iron plating. This report alone would justify his claim to be considered the leading naval architect of that time; it did not bear fruit fully for some years, but its recommendations were ultimately realized.

M. Dupuy did not stand alone in the feeling that radical changes in the construction and propulsion of ships were imminent. His colleagues in the "Genie Maritime" were impressed with the same idea: and in England, about this date, the earliest screw liners--the wonderful converted "block ships"--were ordered. This action on our part decided the French also to begin the conversion of their sailing line-of-battle ships into vessels with auxiliary steam power. But M. Dupuy conceived and carried out the bolder scheme of designing a full-powered screw liner, and in 1847 the Napoleon was ordered. Her success made the steam reconstruction of the fleets of the world a necessity. She was launched in 1850, tried in 1852, and attained a speed of nearly 14 knots an hour. During the Crimean War her performances attracted great attention, and the type she represented was largely increased in numbers. She was about 240 ft. in length, 55 ft. in breadth, and of 5,000 tons displacement, with two gun decks. In her design boldness and prudence were well combined. The good qualities of the sailing line-of-battle ships which had been secured by the genius of Sané and his colleagues were maintained; while the new conditions involved in the introduction of steam power and large coal supply were thoroughly fulfilled. The steam reconstruction had scarcely attained its full swing when the ironclad reconstructor became imperative. Here again M. Dupuy occupied a distinguished position, and realized his scheme of 1845 with certain modifications. His eminent services led to his appointment in 1857 to the highest office in the Constructive Corps--Directeur du Materiel--and his design for the earliest seagoing ironclad, La Gloire, was approved in the same year. Once started, the French pressed on the construction of their ironclads with all haste, and in the autumn of 1863 they had at sea a squadron of five ironclads, not including in this list La Gloire. It is unnecessary to trace further the progress of the race for maritime supremacy; but to the energy and great ability of M. Dupuy de Lome must be largely attributed the fact that France took, and for a long time kept, such a lead of us in ironclads. In the design of La Gloire, as is well known, he again followed the principle of utilizing known forms and dimensions as far as was consistent with modern conditions, and the Napoleon was nearly reproduced in La Gloire so far as under-water shape was concerned, but with one gun deck instead of two, and with a completely protected battery. So long as he retained office, M. Dupuy consistently adhered to this principle; but he at the same time showed himself ready to consider how best to meet the constantly growing demands for thicker armor, heavier guns, and higher speeds. It is singular, however, especially when his early enthusiasm for iron ships is remembered, to find how small a proportion of the ships added to the French Navy during his occupancy of office were built of anything but wood.

Distinctions were showered upon him. In 1860 he was made a Councilor of State, and represented the French Admiralty in Parliament; from 1869 to 1875 he was a Deputy, and in 1877 he was elected a Life Senator. He was a member of the Academy of Sciences and of other distinguished scientific bodies. Of late his name has been little connected with ship design; but his interest in the subject was unabated.

In 1870 M. Dupuy devoted a large amount of time and thought to perfecting a system of navigable balloons, and the French Government gave him great assistance in carrying out the experiments. It does not seem, however, that any sufficient success was reached to justify further trials. The theoretical investigations on which the design was based, and the ingenuity displayed in carrying out the construction of the balloon, were worthy of M. Dupuy's high reputation. The fleet that he constructed for France has already disappeared to a great extent, and the vessels still remaining will soon fall out of service. But the name and reputation of their designer will live as long as the history of naval construction is studied.--_The Engineer_.

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THE USE OF GAS IN THE WORKSHOP.

At a recent meeting of the Manchester Association of Employers, Foremen, and Draughtsmen of the Mechanical Trades of Great Britain, an interesting lecture on "Gas for Light and Work in the Workshop" was delivered by Mr. T. Fletcher, F.C.S., of Warington.

Mr. Fletcher illustrated his remarks with a number of interesting experiments, and spoke as follows:

There are very few workshops where gas is used so profitably as it might be; and my object to-night is to make a few suggestions, which are the result of my own experience. In a large space, such as an erecting or moulder's shop, it is always desirable to have all the lights distributed about the center. Wall lights, except for bench work, are wasteful, as a large proportion of the light is absorbed by the walls, and lost. Unless the shop is draughty, it is by far the best policy to have a few large burners rather than a number of small ones. I will show you the difference in the light obtained by burning the same quantity of gas in one and in two flames. I do not need to tell you how much the difference is; you can easily see for yourselves. The additional light is not caused, as some of you may suppose, by a combined burner, as I have here a simple one, burning the same quantity of gas as the two smaller burners together; and the advantage of the simple large burner is quite as great. It is a well-known fact that the larger the gas consumption in a single flame, the higher the duty obtained for the gas burnt. There is a practical limit to this with ordinary simple burners; as when they are too large they are very sensitive to draught, and liable to unsteadiness and smoking. I have here a sample of a works' pendant or pillar light, which, not including the gas supply-pipe, can be made for about a shilling. For all practical purposes I believe this light (which carries five No. 6 Bray's union jets, and which we use as a portable light at repairs and breakdowns) is as efficient and economical a form as it is possible to make for ordinary rough work. The burners are in the best position, and the light is both powerful and quite shadowless; giving, in fact, the best light underneath the burners. It must, of course, be protected in a draughty shop; and on this protection something needs to be said.

Regenerator burners for lighting are coming into use; and, where large lights are required for long periods, no doubt they are economical. Burners of the Bower or Wenham class would be worth adopting for main street or open space lighting in important positions; but when we consider that, with the fifty-four hours' system in workshops, artificial light is only wanted, on an average, for four hundred hours per annum, we may take it as certain that, at the present prices of regenerator burners, they are a bad investment for use in ordinary work. We must not forget that the distance of the burner from the work is a vital point of the cost question; and, for all except large spaces, requiring general illumination, a common cheap burner on a swivel joint has yet to meet with a competitor. Do not think I am old-fashioned or prejudiced in this matter. It is purely a question of figures; and my condemnation of regenerator burners applies only to the general requirements in ordinary engineering and other work shops where each man wants a light on one spot only.

Some people think that clear glass does not stop any light. This is a great mistake, as you will find it quite easy to throw a distinct shadow of a sheet of perfect glass on a white paper, as I will show you. Opal and ground glass throw a very strong shadow, and practically waste half the light. It is better to have a white enameled or whitewashed sheet-iron reflecting hood, which will protect the sides from wind, if such an arrangement suits other requirements.

I have endeavored in the engraving below to reproduce the shadows thrown by different samples of glass. This gives a fair idea of the actual loss of light involved by glass shades.

When lights are suspended, it is a common and costly fashion to put them high up. When we consider that light decreases as the square of the distance, it will be readily understood that to light, for instance, the floor of a moulding shop, a burner 6 feet from the floor will do as much work as four burners, the same size, placed 12 feet from the floor. It is therefore a most important matter that all lights should be as low as possible, consistent with the necessities of the shop, as not only is the expense enormously increased by lofty lights, but the air becomes more vitiated and unpleasant, interfering with the men's power of working. Any lights suspended, and, in fact, all workshop lights, must have a ball-joint or universal swivel at the point where they branch from the main, as they are liable to be knocked in all directions, and must, therefore, be free to move to prevent accidents. It is better to have wind-screens, if necessary, rather than glass lanterns, as not only does the glass stop a considerable amount of light when clean, but it is in practice constantly dirty in almost every workshop or yard.

For bench work and machine tools, each man must have his own light under his own control; and in this matter a little attention will make a considerable saving. The burners should be union jets--_i. e._, burners with two holes at an angle to each other--not slit or batswing, as the latter are extremely liable to partial stoppage with dust. Where batswing burners are used, I have often seen fully 90 per cent. more or less choked and unsatisfactory; whereas a union jet does not give any trouble. It is not generally known that any burner used at ordinary pressures of gas gives a much better light when it is turned over with the flat of the flame horizontal, until the flame becomes saucer-shaped, as I show you. You can see for yourselves the increase in light; and in addition to this the workman has the great advantage of a shadowless flame. In practice, a burner consuming 5 cubic feet of gas per hour with a horizontal flame is a better fitter's than an upright burner with 6 cubic feet per hour. I do not believe in the policy of giving a man a poor light to work by--it does not pay; and I never expect to get a man to work properly with smaller burners than these. We have a good governor on the main: and the lights are all worked with a low pressure of gas, to get the best possible duty. As a good practical light for a man at bench moulding, the one I have here may be taken as a fair sample. It is free to move, and the light is as near the perfect position as the necessities of the work will permit. When the light is not wanted, by simply pushing it away it turns itself down; the swivel being, in fact, a combined swivel and tap.

You will see on one of the lights I have here, a new swivel joint, which has been patented only within the last few days. The peculiarity of this swivel is that the body is made of two hemispheres revolving on each other in a ground joint. It will be made also with a universal movement; and its special advantage, either for gas, water, or steam, is that there is no obstruction whatever to a free passage--in fact, the way through the swivel body is larger than the way through the pipes with which it is connected. It can easily be made to stand any pressure, and if damaged by grit or dirt it can be reground with ease as often as necessary without deterioration, whereas an ordinary swivel, if damaged by grit, has to be thrown away as useless.

For meals, where a steam-kettle is not used, it is the best policy to have a cistern holding about 1½ pints for each man, and to boil this with a gas-burner. The lighting of the burner at a specified time may be deputed to a boy. If the men's dinners have to be heated, it is easy to purchase ovens which will do all the work required by gas at a much cheaper rate than by coal, if we consider the labor and attention necessary with any coal fire. Not that gas is cheaper than coal; but say we have 100 dinners to warm. This can be done in a gas-oven in about 20 minutes, at a cost for gas of less than 1d.; in fact, for one-fourth the cost of labor only in attending to a coal fire, without considering the cost of wood or coals. Gas, in many instances, is an apparently expensive fuel; but when the incidental saving in other matters is taken into consideration, I have found it exceedingly profitable for all except large or continuous work, and in many cases for this also. I only need instance wire card-making and the brazing shops of wire cable makers to show that a large and free use of gas is compatible with the strictest economy and profitable working.

Of all the tools in a workshop, nothing saves more time and worry than two or three sizes of good blowpipes and an efficient blower. I have seen in one day more work spoilt, and time lost, for want of these than would have paid for the apparatus twice over; and in almost every shop emergencies are constantly happening in which a good blowpipe will render most efficient service. Small brazing work can often be done in less time than would be consumed in going to the smith's hearth and back again, independently of the policy of keeping a man in his own place, and to his own work. The shrinking on of collars, forging, hardening, and tempering of tools, melting lead or resin out of pipes which have been bent, and endless other odd matters, are constantly turning up; and on these, in the absence of a blowpipe, I have often seen men spend hours instead of minutes. Things which need a blowpipe are usually most awkward to do without one; and men will go fiddling about and tumbling over each other without seeing really what they intend to do. They are content, as it all counts in the day's work; that it comes off the profits is not their concern. It will, perhaps, be new to many of you that blowpipes can easily be made in a form which admits of any special shape of flame being produced. I have made for special work--such as heating up odd shapes of forgings, brands, etc.--blowpipes constructed of perforated tubes formed to almost every conceivable shape; these being supplied with gas from the ordinary main and a blast of air from a Root's or foot blower. I have here an example of a straight-line blowpipe made for heating wire passed along it at a high speed. The same flame, as you no doubt will readily understand, can be made of any power and of any shape, and will work any side up; in fact, as a rule, a downward vertical or nearly vertical position is usually the best for any blowpipe. As an example of this class of work, I may instance the shrinking on of collars and tires, which, with suitable ring-burner and a Root's blower, could be equally heated in five minutes for shrinking on; in fact, the work could be done in less time than it would usually take to find a laborer to light a fire. When the rings vary much in size, the burners can easily be made in segments of circles. But then they are not nearly so handy, as each needs to be connected up to the gas and air supply; and it is, in practice, usually cheaper to have separate ring burners of different sizes. Of course, you will understand that a ½-inch gas-pipe will not supply heat enough to make a locomotive tire red hot, and that for large work a large gas supply is necessary. Our own rule for burners of this class is that the holes in the tube should be 1/8 to 1/10 inch in diameter, from ¼ to ½ inch pitch; and the area of the tube must be equal to the combined area of the holes. The gas supply-pipe must not be less than half the area of the burner-tube. Those of you who wish to study this matter further will, I think, find sufficient information in my paper on "The Construction of High-Power Burners for Heating by Gas," printed in the Transactions of the Gas Institute for 1883, and in the papers on the "Use and Construction of the Blowpipe" and "The Use of Gas as a Workshop Tool."

No doubt many of you have been troubled with the twisting of some special light casting, and will, perhaps, spend hours in the risky operation of bending an iron pattern so as to get a straight casting. A ladleful of lead and tin, melted in a small gas-furnace, will, in a few minutes, give you a pattern which you can bend and adjust to any required shape. It enables you to make trials to any extent, and get castings with the utmost precision. There is also this advantage, that a soft metal pattern can be cut about and experimented with in a way which no other material admits of. Awkward patterns commence with us with plaster, wax, sheets of wet blotting paper pasted together on a shape or wood; but they almost invariably make their appearance in the foundry after being converted into soft metal by the aid of a gas-furnace. I refer, of course, to thin, awkward, and generally difficult castings, which, under ordinary treatment, are either turned out badly or require a great amount of fitting. As an illustration of the use of this system of pattern-making, I have here two castings of my own, from patterns which, under the ordinary engineer's system, would be excessively costly and difficult to make as well as these are made. The surface is a mass of intricate pattern work and perforations. To produce the flat original, as you see it, a small piece of the pattern is first cut, and from this a number of tin castings are made and soldered together. From this pattern, reproduced in iron for the sake of permanence, is cast the flat center plate you see. To produce the curved pattern I show you, nothing more is necessary than to bend the tin pattern on a block of the right shape, and we now get a pattern which would puzzle a good many pattern-makers of the old style.