There are many advantages which a steam cagine on this construction possesses, beyond anything of the kind hitherto invented; a few of which the inventor thus enumerates :

1st. It is subject to little or no friction.

2ndly. It may be erected at a small expense, when compared with any other sort of steam engine.

3rdly. It has every advantage which may be attributed to Boulton and Watt's engines, by condensing out of the receiver, either in the penstock or at the level of the water.

4thly. Another very great advantage is, that the water in the upper part of the pipe adjoining the receiver acquires a heat by its being in frequent contact with the steam, very nearly equal to that of boiling water hence the receiver is always kept uniformly hot, as in the case of Boulton and Watt's engines.

5thly. A very small stream of water is sufficient to supply this engine (even where there is no fall), for all the water raised by it is returned into the reservoir H H H. From the foregoing reasons it would seem that no kind of steam-engine is better adapted to give rotary motion to machinery of every kind than this. Its form is simple, and the materials of which it is composed are cheap; the power is more than equal to any other machine of the kind, because there is no deduction to be made for friction, except on account of turning the cocks, which is but trifling.

But it should be observed on the other hand, that one of the properties of this machine, enumerated by the inventor as an advantage, would be found more a defect than otherwise; we allude to the water in the upper part of the pipe being heated by the steam. For though less steam would be lost by condensation, yet it should be remembered that it is impossible to form a vacuum on the surface of boiling water. The only way, therefore, that the water would be raised up the column B, would be by the condensation in C being more rapid than the steam could be generated from the boiling water in B. But we apprehend steam would be generated thus almost as quick as it could be condensed, and therefore the operation of filling B would prove very slow. The addition of a non-conducting float might probably, in part, obviate this objection.

CHAPTER V.

CONTENTS. ORIGIN OF THE STEAM BOAT.-EVANS'S ENGINE AND EXPERIMENTS. ROBERTSON'S ENGINE.-TREVITHICK AND VIVIAN.-MURRAY'S PORTABLE ENGINE-WOOLF'S BOILER, &c.-HORNBLOWER'S STEAM WHEEL.-BOAZ' IMPROVEMENTS ON SAVERY.-TROTTER'S ROTATIVE ENGINE.-FLINT'S ENGINE.-WILCOX'S ROTATORY ENGINE.-MAUDSLAY'S PORTABLE ENGINE.

OUR history is now brought down to the time in which the minds of ingenious mechanics were actively engaged in the project of applying the steam engine to propelling vessels. The idea had, as we have shown, been entertained both by Savery and Hulls, the latter of whom obtained a patent for the application of the crank to Newcomen's engine, with the expectation of carrying his plan into effect

by this means. But the steam engine was at that date too imperfect to admit of success; and we cannot, therefore, attach greater importance to the schemes of these individuals, than we should to the projects of numberless other men to whom the idea had, no doubt, frequently occurred long before the steam boat was brought into successful operation. Who the person was that made the first attempt to carry into effect this most important improvement, has, like most such meritorious inventions, become the subject of dispute. It appears that the earliest experiments tried in England were in 1801: but if we may credit the statements of a most ingenious mechanic, (Mr. John Evans, of America,) it appears he had published a description of a method of driving boats by steam, in 1785. Untoward circumstances prevented Mr. Evans from carrying his plan into effect until 1804; but he does, in our opinion, fully establish his claim to the first contrivance of a practicable steam boat. We shall insert Mr. Evans's own account of the commencement and progress of his ideas and experiments, as we consider them sufficiently important to merit every publicity.

[For this detail we must refer our readers to Mr. Galloway's History, p. 93 to 99, which our limits in this Work do not admit the insertion of; we shall, therefore, pass on to Mr. Evans's descriptive account of his valuable Steam Engine.]

"It appears necessary to give the reader some idea of the principles of the steam engine which is to produce such new and singular effects; and this I will endeavour to do in as few words as I can, by showing the extent to which the principles are already applied.

"To make steam as irresistible or powerful as gunpowder, we have only to confine it, and to increase the heat by adding fuel to the boiler. A steam engine, with a working cylinder, only nine inches in diameter, and the stroke of the piston three feet, will exert a power sufficient to lift from 3000 to 10,000 lbs. perpendicularly, two and a half miles per hour. This power, applied to propel a carriage on level roads or railways, would drive a very great weight with much velocity, before the friction upon the axletrees, or the resistance of the atmosphere, would balance it.

"This is not speculative theory. The principles are now in practice, driving a saw-mill, at Manchacks, on the Mississippi; two at Natchez, one of which is capable of sawing 5000 feet of boards in twelve hours; a mill at Pittsburgh, able to grind twenty bushels of grain per hour; one at Marrietta, of equal power; one at Lexington, (Kentucky,) of the same power; one a paper-mill, of the same power; one of one-fourth the power, at Pittsburgh; one at the same place of three and a half times the power, for a forge, and for rolling and slitting iron; one of the power of 24 horses, at Middletown, (Connecticut,) driving machinery of a cloth manufactory; two at Philadelphia, of the power of five or six horses; and many making for different purposes; the principles applying to all cases where power is wanted to drive machinery.'

Mr. Evans at the same time describes his own steam engine, which is well known to be in very general use in America.

A the boiler, B the working cylinder, C the lever beam, D the fly wheel, E the cistern or condenser, F the cold water pump, G the supply pump, H the fire place, I the chimney flue, K the safety valve, which may be loaded with from 100 to 150 lbs. to the inch area; it will never need more, and it must never be fastened down.

The boiler being filled with pure water (rain or distilled water) as high as the dotted line, and the fire applied, the smoke enters the centre flue, which passes through the centre of the water to ascend the flue I, and thus acts on a large surface.

When the steam lifts the safety valve, it is let into the cylinder by opening the throttle valve, and drives the piston up and down, which, by the rod 1, gives motion to the fly wheel; and the wheel 2 gives motion to a shaft, passing through the supports of the cylinder to turn the spindle of the rotary-valves, 3, 8, which lets the steam both into and out of the cylinder, at the proper time.

The steam, escaping by the pipe 4, curved backwards and forwards in a zigzag form, and immersed in the water in the cistern E, (which is supplied by the cold water pump F,) is condensed; and the distilled water formed thereby descends, by the pipe 5, into the supply pump G, and is forced into the boiler again by the pipe 6.

But as boiling disengages air from the water, so the shiftingvalve, 7, is necessary. This valve lifts at every puff of the steam, and a small quantity escapes; and it shuts, and a vacuum is instantly formed, as the crank passes the dead points.

The small waste of water may be replaced by condensing water in the cistern E, and causing it to run down the pipe G, through a hole in the key of a stop-cock one-32nd part of an inch in diameter; a small hole, indeed, to supply a boiler of a steam engine of twenty horses power.

To be continued.

Discoveries & Processes in the Useful Arts.

ADHESION OF GLUE.-Mr. Bevan has found that when two cylinders of dry ash, 13 inches in diameter, were glued together, and after twenty-four hours torn asunder, that 1260 lbs. were required for the purpose, and consequently that 715 lbs. were required to overcome the adhesion of one square inch of the glued surfaces. The glue was freshly made, and the season very dry. Much smaller powers were obtained with glue which had been frequently melted, the results being then from 350 to 560 lbs: Upon examining the separated surfaces of the first experiment, the glue appeared to be very thin, and did not entirely cover the wood, hence the estimation must be beneath the truth. From a subsequent experiment on solid glue, Mr. Bevan finds that the cohesion equals 4000 lbs. to the square inch, from which he infers, that the application of this substance as a cement is susceptible of improvement.

The lateral cohesion of dry and seasoned Scotch fir, cut down in 1825, was 562 lbs. per square inch, and that of Memel fir, across the grain, from 540 to 840 lbs. Phil. Mag.

THE PLEXIMETER.—An instrument, under this name, has been invented by a French surgeon, for the purpose of ascertaining (which it is said to do with great accuracy) the existence of any plethoric or other effusion in the chest or abdomen. It consists of a plate of ivory, like the lid of a snuff-box, which is to be fixed op the part to be examined in such a way as to render the sound produced upon it by percussion very distinct. The presence of so small a quantity as two glasses of liquid has been ascertained by the Pleximeter. It likewise enables the operator to discover if the liver or the spleen is enlarged, or if the peritoneum contains any air.

NEW OIL LAMP.-Mr. Davies, a lecturer at Manchester, has exhibited a lamp, in which the wick was superseded by a capillary glass tube. The tub was placed in a small wooden basin, which floated upon the oil contained in a glass vessel. A Manchester paper says, "The flame which was less than an ordinary candle, was uncommonly clear. This lamp consumes very little oil, and appears to be well adapted to the purposes of persons who keep a light in their chamber during the night."

LIST OF NEW PATENTS, NOVEMBER, 1826.

FIRE-ARMS.-To Benjamin Newmark, of Cheltenham, for improvements in fire-arms. Sealed 7th November. Six months,

MEDALS.-To Edward Thomason, of Birmingham, for improvements in the construction of medals, tokens, and coins. 9th November. Six months.

CARRIAGES.-To Henry C. Lacy, of Manchester, for a new invented apparatus, on which to suspend carriage bodies. 18th November. Six months.

NAVIGATION.-To B. Woodcroft, of Manchester, for improyements in wheels and paddles for propelling boats, &c. 18th November. Six months.

TO OUR READERS AND CORRESPONDENTS.

J. R. had better consult Dr. Ure's Chemical Dictionary, where he will meet with all the information he seeks.

The series of papers proposed by C. W. we shall be happy to avail ourselves of at the commencement of our fifth volume, the large extracts we are now making from Mr. Galloway's History of the Steam Engine with a view to its early completion, preventing their insertion in the present volume. The letter from Abergavenny has been received.

Mr. Wood's favour has been received; we shall avail ourselves of the first opportunity to attend to his request.

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