324

GILMAN'S IMPROVEMENTS IN STEAM-ENGINES,

The three very first lines of the first paragraph contain a most uncandid and incorrect statement; they run thus "In 1826 my attention was directed to the best and most economical method of generating steam, &c." Why does Mr. Gilman say in 1826? Did he not take out a patent, dated April 13, 1825, " for certain improvements in generating steam," &c.? Is he ashamed of his labours previous to 1826? I presume that is the case; for certainly if any thing can exceed the absurdity of Gilman's generator of 1826, it is Gilman's patent of 1825. As I think them companions, too worthy of each other to be separated, I copy the following conclusion of the specification of that patent:" And we do hereby expressly ascertain and limit our claims under the hereinbefore in part recited patent to the following particulars (that is to say), First, we claim the principle of spreading thin sheets of water, by means of revolving agitators, over the internal surfaces of cylindrical boilers when placed horizontally, or but moderately inclined in the modes herein before described. Secondly, we claim the particular arrangements of the tubelined fire-place and flues, which are shown in figs. 1, 2, and 3, and described herein with their several modifications, that are mentioned for the purpose of heating the water previously to its being introduced into our boilers. Thirdly, we claim the mode of connecting and joining together our tubes or pipes in each of the tiers, which is shown in figs. 4 and 5, and described herein. Fourthly, we claim the having of a forcing-pump or pumps constantly attached to the boilers, or steam-pipes or chambers, for the purpose of readily proving their strength on all necessary occasions. Fifth, we claim the applying of tar or pitch, either mineral or vegetable, to increase the inflammability, and perfect the combustion of ordinary fuel for the generating of steam; and, sixthly, we claim the principle of using highsteam in two or more steam-engine cylinders, without condensing, to assist our engine by the vacuum formed thereby, in the manner hereinbefore described. In witness whereof, &c."

Now I would ask, as relates to the

first of these claims, what, in the name of common sense, can be the use or advantage of agitating water in close vessels for producing steam? Secondly, how could water possibly be passed through such an immense length of tubeing placed in a furnace, without its being converted into steam, long before its arrival at the boilers? Next I would ask, what possible originality or novelty is there in the third and fourth claims for joints and forcepumps? The fifth claim, I admit, has great merit, as the originality and stretch of genius in burning tar and pitch along with ordinary fuel are very great indeed.* I lastly, in order to show the originality of the sixth claim, refer your readers to a patent taken out by Mr. Arthur Woolf, dated June 7, 1824; the specification of which describes the use of two cylinders in a similar, but better way than that pointed out by Mr. Gilman.

For further information respecting Mr. Gilman's patent, I refer such of your readers as are fond of such shimble shamble stuff to the patent itself, and shall now proceed with the paper more immediately in question.

The second paragraph commences thus-" In that year the apparatus, exhibited by the accompanying drawings, was executed, and is now in existence." This ipse dixit it is not within my province to deny; but, in reply to his statement, that from 200 to 300 lbs. per inch pressure were employed by it, I will fearlessly assert that he never did and never could do any such thing. So far from his doing that, I will challenge him to prove that he ever with that apparatus (and in the way he describes) subjected the fuel to combustion, under a pressure of so much as 1lb., much less of 300 lbs. to the square inch, above the pressure of the atmosphere. If the apparatus be really in existence, he can easily, before competent witnesses, disprove the assertions I have already made, as well as those I shall make in the course of this letter.

As the third and fourth paragraphs of Mr. Gilman's paper describe his

Two patents were taken out for the same wise purpose by Mr. John Christie; the first dated Oct. 9, 1823, and the last Feb. 28, 1824; so that even here Mr. Gilman is not original.

GILMAN'S IMPROVEMENTS IN STEAM-ENGINES.

generator and the mode of operating with it, I will now point out some of its defects and incongruities, and the total impossibility of his doing with it what he has stated, which will prove that the use of such a generator, if not indeed (as I shrewdly suspect) the generator itself, is merely the chimera of the same brain that concocted the patent of April 13, 1825.

In the first place, a vessel of 2 feet in diameter, with the bottom and cover attached to it by only 12 bolts, in the manner shown by the drawing, is no more capable of bearing a pressure of 200 or 300lbs. on the square inch, without suffering the steam to escape, than it is of bearing a pressure of 2000 or 3000lbs. per square inch. I would ask Mr. G. how the inner and outer cylinders of the generator are united to the cover and bottom, so as to support even a very low pressure without flanches, each cylinder being only one inch thick? He has certainly hit upon one great excellence of the top of his generator, viz. that it acts like an immense safety-valve! It will, indeed, act so, and let out all high-pressure vapours, as I have before stated; but why he has not paid the same compliment to the bottom as well as the cover I don't know, for it is evident it will produce the same effect, so that Mr. Gilman has the advantage of two immense safety-valves!!

In the second place, Mr. Gilman's description of the mode of operating with his generator is impracticable. He says "In using this generator the method of operating is first to fill the fire-chamber full of fuel, and when the fuel has acquired a state of intense ignition, the cap of the flue, &c.' Now, as he says the internal cylinder is 18 inches diameter at the bottom, it must, as shown by the drawing, be about 24 times that depth, or 45 inches deep. Now, I defy Mr. Gilman, or any man living, to get half that depth of fuel into a state of intense ignition by blowing in air in the way he has mentioned. About 12 to 15 inches deep of fuel is all that can be got into that state; for when a quantity of fuel is put in at the top of the cylinder, that at the bottom is so far consumed before that

325

at the top gets to a red heat, as to cause the whole mass to be reduced to the depth above mentioned. I speak not from theory but from practice on this point; if I am wrong, Mr. G. can easily contradict me; for as his apparatus is now in existence, he can easily, before witnesses, show whether he can get 45 inches deep of fuel into a state of intense ignition. What I have said proves that he has not used such a generator as he describes even experimentally, and this. I am about to prove still more fully. I will even show that between the time of making his drawings, and that of giving his descriptions thereof, his fertile genius came to his aid and pointed out an alteration in his apparatus. For, in the drawing fig. 2, the pipes F are shown as branching from nearly the top of the internal cylinder above the water; while in the 7th paragraph of his paper he says "the four pipes F, instead of being attached to the fire-chamber above the fire, should be fixed about the middle of the burning mass." Now it is quite clear if he had really used the generator, and that his description were the result thereof, the drawing would have shown these pipes in the middle of the burning mass, and it is equally clear that something struck him in the time that elapsed between the drawing being made and the above alteration appearing in the description thereof. I suspect the reason for the alteration was this, that as one air-pipe A enters underneath the grate and below such an immense mass of fuel, and the other pipe branching from it enters above the fuel, it struck him that all the air would pass into the generator by the last-mentioned branch, and of course above the fuel; the obstruction of such a mass preventing any from passing below and through it, as air, like other fluids, will take the passage the least obstructed. Perhaps also he thought (not without reason) that the pipes F, if out of the water, would soon be destroyed by the fire; but in avoiding being wrecked upon Scylla, he has engulphed himself in Charybdis: for if the pipes F be fixed about the middle of the burning mass, it is evident they will in a few minutes be choked

326

GILMAN'S IMPROVEMENTS IN STEAM-ENGINES.

by small bits of fuel and ashes being blown into them, when Mr. G.'s valves at the bottom of the pipes L would be kept open by such ashes, &c., and the water would get into the fire-chamber. What would then become of poor Mr. G.'s burning mass? But supposing such burning mass met with no such dire misfortune, what would become of the ashes and scoria formed on the grate by the combustion of the fuel, even in a mere experiment? Where is the ash-pit and the means of withdrawing them? The former, it is true, might be blown into those useful pipes F, but a blast would in a very short time produce so much scoria or slagg as would effectually prevent any air from passing through the fuel. Even if there were not such an immense depth of it as Mr. Gilman describes, and all the air were to pass above the fuel through the pipes attached to the two orifices L, the fire must consequently be extinguished.

Have I said enough, Mr. Editor, to prove that the pretence of this apparatus having been really used even experimentally, cannot possibly be founded in fact? If not, I will trouble you a little farther. Mr. G. does not even pretend that having once closed up the fuel, he could introduce any more; for if he had a means of so doing, he would gladly have included it in his drawings and in his description thereof. I really think I need not enter into the very obvious reasons why without such a means of feeding the fire, the generator could not be put into operation at all. I recollect when I was a boy, either hearing or reading a sermon (I forget which) preached by a divine (you will say a no very learned one) from a part of the 12th verse of the 10th chapter of Joshua," Sun, stand thou still upon Gibeon." He divided his sermon into three parts, consisting, as he said, of the three several motions of the sun-first, there was, he said, the direct motion of the sun; secondly, the retrograde motion of the sun; and, thirdly," the MOTION mentioned in my text-the sun stood still." Now for the application. I have no doubt the motion of any engine to which Mr. Gilman's generator might be ap

plied, would be the third motion or division of the preacher's sermonand the engine stood still.

Apologising for this digression, we will proceed to Mr. Gilman's fifth paragraph, where he says, " With respect to combustion under great pressure, I have never discovered but that it proceeded as well in that way as by common draughts under the ordinary atmospheric pressure." I fully believe him here; I believe he never did discover but that combustion proceeded as well under great pressure as under the ordinary atmosphe ric pressure; for this plain reason, that he never produced or even saw produced the combustion of fuel under great pressure for the purposes he points out. I beg to refer to two patents taken out by Mr. Samuel Hall, the first dated April 8, 1824, and the second dated May 31, 1828; no one on inspecting them will doubt for a moment that Mr. Gilman's ideas upon combustion under high-pressure are borrowed therefrom, and that in fact Mr. Gilman's generator is a rude imitation of the generators described in Mr. Hall's two patents.

As to Mr. Gilman's crude philosophy, in which he indulges in his fifth and sixth paragraphs, we will not dispute the matter with him, as I am more (as my name indicates) for practice than theory; I will merely say that in his great simplicity he takes no notice of the immense volume of gases resulting from the combination during combustion of oxygen with the carbon of the fuel. Poor carbonic acid, &c. how greatly you are neglected by Mr. Gilman!

I now proceed to paragraph the eighth, containing two modifications or flights of Mr. Gilman's genius, some of which, he says, have been put in practice. I wish he would from the result of such practice inform us how soon, according to the first modification, the top of the generator and pipes F (when so unfortunate as to be taken from their protector, water) become red-hot, and how soon they would be destroyed. With respect to the second modification, it is clearly intended to be a hard blow at Messrs. Braithwaite and Ericsson, who have really brought a very useful locomo

LIEUT, SKENE's paddle-WHESLO.

328

INSTRUMENT FOR DRAWING HYPERBOLAS.

wish to see her they will find her in the Surrey canal; she is for sale without engines.

One word to Mr. Hebert, editor of the Register of Arts, Engineer, &c. Does he still think, or rather say, that a vessel fitted with my machinery would not reach Greenwich in one

DESCRIPTION OF AN

day against the tide? If he does, let
him exhibit his proof.
I am, Sir,
Yours respectfully,

49, Fenchurch-street,
Dec. 26, 1829.

A. M. SKENE.

INSTRUMENT, INVENTED BY MR. K. CHILD, FOR
DRAWING HYPERBOLAS.

A, B, C, are three cylindrical rods, on which move freely the respective slides h, M, and K. C moves on a centre at the flat end of B, as at D, and can be set by means of the arc o, p, to any required angle with B. A can likewise be adjusted by the assistance of the sliding-socket on F, and the thumb-screw a, to any angle with B. The flat bar G has a groove in which are placed the pins or centres of the slides K and H, which can be secured in their respective situaFons by the thumb-screws b, d, the

one in the groove n, (in the slide M) and the other on the rod C, but at the same time allowing G to move freely round them. The rod F moves on a centre on the slide M.

The centre of motion of A is at S, (exactly over the centre of the rod B), and for the sake of steadiness it has a notch on the inside of the end E, through which it moves round the semicircular part of the slide M, when under adjustment for the required angle.

In this arrangement of the instru