HULLS' STEAM-BOAT. 201 66 a, chimney coming from the furnace; b, towboat; c, c, two pieces of timber framed together to carry the machine,d; x, y, z, three wheels on one axis to receive ropes, s, t, u; t, being rope that goes into cylinder; m, n, two wheels on same axis with the fans, i, i, i; u, is a rope going from wheel, n, to z; that when the wheels, x, y, z, move forward, moves wheel, n, forward, and the fans along with it; s, a rope going from wheel, m, to the wheel, a, so that when the wheels, x, y, z, move forward, the wheel, m, draws the rope, s, and raises the weight, g, at the same time as the wheel, n, brings the fans forward. "When the weight, g, is so raised, while the wheels, x, y, z, are moving backward, the rope, s, gives way, and the power of the weight, g, brings the wheel, m, forward, and the fans with it, so that the fans always keep going forward, notwithstanding the wheels, x, y, z, move backwards and forwards as the piston moves up and down in the cylinder: o, e, teeth for a catch to drop in from the axis, and are so contrived, that they catch in an alternate manner, to cause the fans to move always forward; for the wheel, m, by the power of the weight, g, is performing its office while the other wheel, n, goes back, in order to fetch another stroke. The weight, g, must contain but half the weight of the pillar of air pressing on the piston, because the weight is raised at the same time as the wheel, n, performs its office; so that it is, in effect, two machines acting alternately by the weight of one pillar, of such a diameter, as the diameter of the cylinder is." Hulls, aware that objections might be urged against its want of originality, endeavours to anticipate them; "if it should be said," says he, "that this is not a new invention, because I make use of the same power 202 HULLS' STEAM-BOAT. to drive my machine, that others have made use of to drive theirs for other purposes, I answer, The application of this power is no more than the application of any common and known instrument used in mechanism for new invented purposes." It may, however, be observed, that he considers that it would not be practicable to place his apparatus on board of the ship which it is required should be moved-but that a separate vessel should be appropriated to its reception, and that this should be used as a tow-vessel; and he urges several economical reasons in favour of his TowBoat. The manner of converting the rectilineal motion of his piston into a rotary one, is very ingenious.* Payne, in his narrative of a new method of expanding fluids, by their being conveyed into certain ignified vessels, where they are immediately rarefied into an elastic impelling force," exhibits considerable originality of idea as well as construction. His boiler, which he called his expanding vessel, was shaped like a balloon, the greater end of which formed the roof; a pipe was carried through the top of this expanding vessel, which had a kind of horizontal drum fixed upon it. On the periphery of the drum or disperser were placed a radiating series of small pipes. The lower end of the vertical pipe, which may be called the axis of the disperser, was formed as a pivot; this turned in a socket, supported by a bracket. The upper end of the pipe (outside of the balloon) was fitted with a cog-wheel, which * About this period three fire-engines were in operation in France, one at Fresne, near Condé; one at a coal mine at Sars, near Charleroi; a third at a lead mine near Namur.-Gensanne, p. 300, vol. vii., Machines Approuvées. + P. 821, vol. XLI. Philosophical Transactions. PAYNE'S BOILER. 203 worked into another. The flue of the furnace encompassed the middle division of the balloon. When water was introduced into the upper end of the vertical revolving-pipe it fell into the drum, and by its revolution was thrown through the small radiating pipes on that portion of the balloon exposed to the action of the furnace, and a rapid production of steam was thus occasioned. The water which was not converted into vapour fell to the bottom or narrow end of the balloon, and was conveyed away by pipes, placed there for that purpose. Payne says, he evaporated forty gallons of water in an hour, which supplied a twenty-four inch cylinder by this method; and in experiments made at Wedgebury and Newcastle he rarefied ninety gallons of water in an hour, by one hundred and twelve pounds of pit-coal, being, he says, about one-third only of the fuel required to do the same thing in common boilers. He stated the expansion of steam at four thousand times the bulk of water which formed it a better guess than any that had yet been offered. It is uncertain whether he succeeded in introducing his clever plan into practice--probably not, for ten years afterwards, Blake, in a paper read before the Royal Society in favour of wide and short rather than narrow and long steam cylinders, notices" that the prodigious vessel of water to be kept boiling, when only an inconsiderable part of it is employed in the work, savours too little of the frugality of nature, which we ought ever to imitate."* In the same year Smeaton gave an account of a self-acting engine on Savery's principle, invented * Philosophical Transactions, p. 200, vol. XLVII. by a Portuguese gentleman. A light ball of copper formed a float within the receiver; this was attached to an axis or spindle, passing through a socket to the outside of the vessel. The float rises and falls, with the rise and fall of the water, and communicates a corresponding motion, to a series of levers or gears on the outside, adjusted to make the motions simultaneous.* By this Mr. de Moura performed the same thing, by means slightly different from those employed by Gensanne some years before. The project which had several times been discussed by the Academy of Sciences, when individuals presented to their notice schemes for moving vessels by other aids than wind or oars, was in 1757 propounded as the subject of their prize essay. The celebrated Daniel Bernouilli demonstrated the effect of several mechanical combinations, which might advantageously supply the power derived from wind or oars. He gave the preference to paddle-wheels, which he + suggested might be moved by steam or gunpowder. Gautier, a canon of Nancy, did not, in his essay, exhibit such unbounded power over the medium by which his ideas were illustrated, as was possessed by the mathematical giant who bore away the prize in this competition; but in the details of his scheme he shows a finer mechanical tact than his rival Bernouilli. A steam-engine, with several ingenious modifications to produce rotary motion, is made to turn paddle-wheels placed at each side of the boat, as recommended by Duquet in 1693. His essay throughout shows him to have been *P. 437, vol. XLVII, Philosophical Transactions. prix, P. 94, tom. vII, Recueil des Pièces qui ont remporté les P. 251. tom. 111, Mémoires de la Société Royale de Nancy. rich in mechanical resources, and we remark with surprise such clear and distinct notions, on a perfectly novel and difficult subject familiar to a man who had always lived in an inland town, and totally ignorant of maritime affairs. It was a favorite project of Dr. Hale's to increase the evaporation from sea-water during the process of making salt, by artificial ventilation.** Kean Fitzgerald, in 1757, applied the Doctor's idea to the production of vapour to supply a fire-engine He inserted one end of a pipe into the water of the boiler, and to the other end he fitted a huge pair of bellows, his project being to blow air through the hot water, which would rise as steam into the cylinder. Putting the bellows in action, he produced as he had anticipated, about a sixth more vapour than was generated when blowing was not resorted to. Here the increase, although considerable, not being quite equal to his expectations, he proceeded to a second trial, in the hope of making a greater impression; a new pair of bellows was constructed for the occasion, larger, stronger, and tighter than those used in the first experiment, but on attempting to blow into the boiler, the bellows stood as stiff as if they had been solid within they were loaded with a weight of several hundred pounds, but still they resisted compression as before. The cause now became obvious, a force must be applied to empty them greater than that which was opposed by the elasticity of the steam in the boiler; but as the top of the bellows had a surface of nine or ten square feet, to place ten or eleven pounds on each square inch of this area, was beyond his ability. : *P. 128, vol. L, Philosophical Transactions. T |