it twenty waggons, each containing three tons of coal, at the rate of four miles an hour. I find, that steam applied to draught carriages, has been used for some years in England, and the practice is extending.

It is with very sincere satisfaction, I announce, that several gen tlemen of considerable mechanical abilities, in our own country, are now turning their attention to the improvement and construc tion of steam engines. Several drawings have been sent to me for opinion and publication, but at present, I can do no more than briefly notice the principles adopted.

In Mr. Fulton's engines, the method of packing the piston, of preserving the prependicularity of the stroke, of communicat ing the rotatory motion, and the form and dimensions of the unwieldy working beam, have been improved, since my time of obser vation.

Mr. French, of New York state, is also constructing engines, with some improvements on Boulton and Watt's, as I have heard, but I do not know exactly what the alterations are.

Mr. Oliver Evans's establishments in Philadelphia and at Pittsburgh, have early and greatly contributed to bring steam engines into use, but I do not accurately understand the point on which his claim to a patent right, is meant to rest. If I had the precise invention explicitly described, I should be glad to give it that currency, to which its novelty may entitle it.

Mr. Rodman, of Washington, South Carolina, has sent me the drawing of an atmospheric engine, working with two cylinders, which appears to possess considerable merit, as to the simplicity and consequent cheapness of the machinery. I do not remark any contrivance to preserve the perpendicularity of the stroke. The construction and situation of his valve, I understand, is much like the method adopted by Mr. French: but about this I am not able to speak with accuracy.

Mr. Ogden, of Pittsburgh, is also engaged on a steam engine, with two cylinders contiguous to each other. He proposes working his steam of whatever density, in two cylinders, to be stopt off at any point. If at one half, the instant one cylinder is half filled, its steam valve is closed, and the steam valve of the other is opened. On the first pistons arriving at the end of its stroke, that of the other cylinder will have performed half a one. Its steam valve will then be closed, and that of the first again opened, as well as its opposite condensing valve: in this manner the motion will be

Regularly continued, each cylinder being alternately half filled with steam.

The pistons act simultaneously, at right angles with each other, and one is at its maximum when the other is at its minimum, so that there is no necessity for a balance wheel as a reservoir of power: for when one piston ceases momentarily to act, the other instantaneously continues the motion in the same direction. The power is communicated to crank wheels worked by shackle bars attached to each piston. If the steam be stopt off at one half, and left to act by its expansive force, the gain is half a cylinder full of steam at each stroke. There is nothing new in two cylinders, or in working by expansive steam, but the getting rid of the balance wheel by the simultaneous action of each piston in the manner above described, I think is new.

Mr. Latrobe of the same place, is erecting a manufactory for steam engines, in which he proposes to make some improvements on the construction of Boulton and Watt: but whether to be used solely for water navigation, or for sale, I know not yet.

So much exertion, and by such men, affords ground to hope that at no distant time, improvements may take place, that will put our Engineers of America, upon a par at least with those of England. But of all the attempts to vary from the common construction, I have seen none that promises so well, as those of Mr. Dowers of Philadelphia. I have carefully examined his drawings, and I think he has skilfully combined a series of improvements, that if put in practice, with great attention to mechanical accuracy, will go near to supercede every variety of steam engine now in use. These improvements contemplated for a double engine, consist in

1st. A more perfect mode of condensing, by the joint application of exposing a large and thin metallic vessel containing the steam, to the action of cold water, as the Rev. Mr. Cartwright proposed and the common method of condensing by injecting the spray of cold water. A plan nearly similar to Mr. Dowers' condenser, is suggested, p. 82 of this Volume.

2ly. Using perpetually the same water, for the boiler, the condenser, and injector; without diminution or the necessity of addition; except what may arise from imperfections in the workmanship of the vessels. In which it is not easy, always to guard against steam leaks, and water leaks. The wormanship being good, this engine must work with a smaller supply of water than any other yet known,

Sly. A more certain mode as I think of discharging the air. It arises to the top of the water, and is thrown out by the valves that open with the upward stroke of the piston that throws the cooled water into the condenser.

4ly. A new, and seemingly effectual method of keeping the wa ter at a regular height in the boiler, by making the condenser discharge any surplus into the boiler.

5ly. Saving and condensing the steam occasionally discharged from the boiler, and which in other engines escapes into the air, so that the boiler and condenser being once supplied with water, this stock of water is not diminished by waste steam, or encreased by extraneous injection water: or varied, except as need may arise from causes depending, not on the principle of working the engine, but from accidental and unavoidable imperfections and wear in the materials and workmanship, or perhaps from slight decomposition of the water itself.

6ly. Boilers on a new, and if the workmanship can be depended on, an improved construction: not much differing in principle, but greatly in form and arrangement from those hitherto employed: being two large boiler-cylinders through which the fire flue runs, and which are furnished with a series of pipes, and one small boiler-cylinder in the centre, over which is a cylindrical reservoir for the steam.

7ly. A rack, or cog-wheel with a handle, by which the ears or plugs, of the plug beam, may be moved and varied at pleasure; so as to regulate as need may require, the opening of two steani valves, additional to the valves of the common engine and by this means, to stop off the steam at any given point or portion. In Watt's engine this is managed by a pin. By means of this regulator, if a fourth part only for instance, of the cylinder full, be thrown in, it can act by its expansive force. So that no steam need be employed, beyond what is necessary to the required work of the engine. The regulating valves, are on a construction different from the common valves, being worked by rods, one within the other. The steam admitted, is also admitted at once, not gradually; which last practice although recommended by Woolf and now common (see p. 186 of this vol.) has disadvantages.

8ly. A new method of augmenting the force of steam, by exposing to considerable heat, a part of the steam that acts on the piston, and mixing it with the steam that proceeds direct from the boiler. Compare this with Mr. Woolf's patent, page 190 of this volume.

9ly. A method of superceding the necessity of a fly wheel, by means of two circular crank and cog wheels attached by shacklebars to the pistons of two cylinders. The crank wheels are cast in the same mould, and move a smaller cog wheel in the centre; so that, when the piston in one cylinder has arrived at the bottom, the piston in the other, is just commencing its descent, and vice The combined force of the pistons in each cylinder, being always the same. Here, no reservoir or accumulation of surplus force in a fly wheel, is necessary to carry the motion past the perpendicular pressure; because, the instant one of the pistons with its attached crank wheel, has spent its force on the middle cog wheel, the other piston with its attached crank wheel, begins to act; driving round the centre cog wheel in a similar and uniform direction. The two large wheels between which the smaller is placed, are connected together by a small beam or brace. This invention is contested by Mr. Ogden; and with the dispute, I have nothing to do. It is worth while however, to compare it with Mr. Cartwright's method of communicating rotatory motion; see p. 84 of this volume.

Mr. Dowers proposes making the valves of the common engine, answer the purpose of his regulating valves. If so, so much the better. There are practical difficulties attending the construction of the boiler, and the augmenter; but they are not insuperable.

If alcohol or ether, or any mixture of alcohol and water, can be used economically in steam engines, as good judges think may be done, this engine will afford the means of using it. But I know of no decisive experiments yet made on this important subject. Mr. Dowers, and I, in my laboratory, past whiskey diluted with from one half to two thirds water, through a red-hot gun barrel, but the gas produced, was small in quantity and not inflammable. It was in fact no more than the air contained in the gun barrel.*

The wasteful and unscientific practices of using steam little higher than to afford mere atmospheric pressure thus neglecting the force to be gained by a small addition of fuel†—and of genes

* The inside however had been previously oxyded.

It is surprising that Mr. Watt who first discovered and demonstrated (see p. 93, and 171 of this volume) that the elasticity of steam being in proportion to its density, its expansion when stopt off at 1-4th, 1-3rd or 1-2 the capacity of the cylinder will produce a power in a much greater ratio than 1-4th, 1-3rd or 1-2 of the whole, should have made so little use of this discovery in his steam engines. The time is approaching when steam of great

rating steam of high temperature and great expansive force, to waste itself in the open air, and in its exist to be counteracted by the resistance of the atmosphere, are thrown aside. The faults both of the European and the American engines, are in a great degree obviated; and we may expect from American ingenuity, a more perfect engine than has yet been devised.

The engine in contemplation, will act by steam at high temperature, as Watt suggested, and Trevethick practised on a large scale it will act by expansive force as has long been the practice in many English engines; and by two cylinders: so as to combine the modern improvements, and obviate modern defects. How far Mr. Dowers has been indebted, if at all, to his predecessors, the yeaders must judge by the references I have made to former pages of the present volume.

I shall indeed rejoice to see some American by and by, still im, prove upon his ideas. T. C.

NOTICES.

Stone Coal. Judge Gibson, of Luzerne, has written me the following letter.

DEAR SIR,

Wilkesbarre, February 23, 1814.

I send you a likeness of one of your friends. There is nothing remarkable in it, except that it is done with the stone coal of this place, instead of Indian ink. It is prepared for use by rub. bing a bit of it on a fine hard stone in gum water, just thick enough to hold the particles in suspension; it is then laid on in the usual way with a camel hair pencil. By comparison with a drawing in

force will diminish the size of boilers; when unwieldy beams and ponde rous fly wheels will be disused; when single engines will give place to double, when expansive power will be used to the utmost; and when no steam will be generated to be thrown away. As yet, I dare not anticipate the time, when water will be laid aside, and alcohol, ether, alkaline gas or hydrogen be substituted in its place. Alcohol and ether are condensible at low temperatures-Ammoniacal gas by the vapour of muriatic acid-and hydrogen by firing it with oxygen, and converting it into water. These are speculations; and so was at one time, the steam engine itself. T.C.