This Machine, though conceived many years ago, can hardly yet be called an invention—if material existence is necessary to justify that appellation: for I have never seen it in action. It may possibly be one of those fascinating conceptions of which my noble friend the late Earl Stanhope used to say—“’tis a beautiful invention—but ’twill not do;” yet I give it with some confidence, because of the great utility it would present, if it’s chief properties should fulfil my expectations.
The principal idea on which it is founded, is this: to use, as power, the expansion of that air which feeds the fire; and again to employ it’s heat heating liquids or rooms, or any similar purpose. The form I have given to the Machine is by no means the only one it admits; nor perhaps the best: but it was indispensable to give the idea (which I hope is not an “airy nothing”) “a local habitation and a name.”
It consists, then, of two cylinders, lying horizontally, of nearly equal length, but of unequal capacity:—one of which A B, ([Plate 24], [fig. 7]) is an air pump with a valve in it’s end a, and another in it’s piston, both opening to the left. The second cylinder C D, is the working cylinder, as much larger than the former, as may belong to the principle of motion already announced. This cylinder receives the piston E, which fits it nicely, but is not stuffed in the present case. (It may perhaps be made tight by some of the methods, used to close metallic pistons.) At all events, this piston is connected with that c, by a frame F G H I, which embraces the whole Machine, in a horizontal position, though here shewn in a vertical. These two cylinders are cast in one piece, together with an upright cylinder, not bored K; the use of which is to receive the earthen chafing dish L M, with it’s fire, made (according to my present views) with coak or charcoal, and lighted before it is introduced. It is needless to say, that this vessel is let down into the cylinder K, by a kind of bucket handle entering any pair of holes in the dish. The top of this latter cylinder is ground to fit the flanch A N: It swings open on one of the bolts and falls to again in a moment, to prevent loss of time in firing. The means of doing this I do not much insist on, from their extreme facility. Nor do I make it a condition to use this method at all. The coak, (or perhaps the coal, or the wood) might be introduced through an upright tube furnished with two slides, one placed close above the top A N, and the other at a proper distance above; so as for one to be always shut. This is nothing more than the System used for feeding high pressure Steam Engines—only this application is to dry substances, which forms no insuperable obstacle.
When now the Machine is fired, the pistons E, and c, are pushed towards b and B respectively; the valve d having been previously opened, and the valve c opening by this very motion—which thus clears the large cylinder of it’s included air, while the air in the pump A B, is brought into contact with the fire; whence a considerable expansion ensues, and a pressure is created tending at the same time to drive the piston c to the right hand, and that E to the left: but acting in the latter case on a larger area, the whole system moves that way, and all the air in the pump A B is driven through the fire: where, being much heated, it acquires great elasticity and developes considerable power—which, by any of the known methods, may be applied to any of the known purposes.
I hope my readers will conclude here, that I allow for the disappearance of the oxigen in this conflagration: but I expect the expansion of the residue (together with what new vapour may be developed) will more than compensate for that loss of volume. By this motion then, the pump A B is again filled with cold air through the valve a; and the piston E flying out of the cylinder C D, the hot air it contained rushes into the pipe o, and thence goes to perform any heating operation that may be desired. But further, this same recession of the piston E strikes the stem of the valve d against the cover e, and opens that valve; by which means the large piston is at liberty to reach again it’s inner position b: where the bar b closes it’s valve d and prepares the Machine for a new stroke. For, as before, the pump or cylinder A B, is full of cold air, and by the backward motion of it’s piston exposes that air to the fire in K: whence arises the renewal of all the former phenomena.
Many ideas, and doubtless some objections, will present themselves to the readers of these pages; of which I shall probably anticipate some, by noticing a few less important particulars.
And first, is it not to be feared that the vertical cylinder K, and the whole system K C D E will become too hot—nay acquire a red heat, and thus introduce danger? The answer, I think, is that the fire must be lessened, or the Machine enlarged, until this danger disappears: for by heating air to any thing like a red heat (without attaining it) the expansion will be immense: and probably beyond our wants or wishes. The chaffing dish then (if that is used) must be lessened, that the air from A B may partly circulate round it, instead of going wholly through the fire: thus cooling the vertical cylinder K, and diminishing the intensity of the heat in the working cylinder. Further, the two cylinders C D and K, might be inserted in the bottom of a boiler, and surrounded with water; through which also, may be conducted the pipe O, so as to concur in the same effect of heating that water, while the steam thus accruing from the double use of this heat, may be made to drive an engine, heat a room, or fulfil any common purpose.