who suggested its practical application to this purpose. He proposed to employ an engine on Savery's plan, and added machinery to open and shut the cocks. Two or three large engines have been constructed in this country, which have since been employed in Holland with the most beneficial effects; and there is no doubt but that their value, when duly appreciated, will be sufficiently obvious. This is more particularly the case in those tracts of low and swampy ground, whose outfall lies at a considerable distance, and which has previously to pass through ground of a higher level. In some instances it has been found necessary to cut drains or rather trenches of from ten to twenty feet in depth, and this too for several miles in length.

Mr. Savory, of Downham, who, we understand, has given considerable attention to this branch of civil engineering, states the cost of an engine of twenty-horse power fitted up for this purpose at fifteen hundred pounds, and that this will do as much work as a mill with a forty feet sail, when in full velocity. The advantages that may be derived from the use of steam in the fens or marsh country, appears, from the same authority, to be of the first importance. In case of intense frost, the uniform velocity, with the opportunities of communicating heat, would prevent the engine from freezing, to which, from the uncertainty of winds, the other engines are very much subject. The

consequence is, that a great fall of snow coming at the same time that the mills have not been in a state to prepare the ditches to receive the overplus water which it occasions, an inundation generally takes place in the fens; and, as the waters rise very rapidly under these circumstances after a thaw, it frequently occurs, that when the mills are set at liberty from the effects of ice, they are for some days incapable of successfully opposing the accumulation of water. On the other hand, by adopting the means of steam, the engines, would be working in full effect during the continuance of a frost, and the ditches being kept proportionably low, would at all times be capable of discharging the water, and thus prevent inundation.

Mr. S. concludes this part of a very useful paper on the subject, by observing, that "as to a district of country which requires draining without any engines upon it, at the time of its being undertaken, it is a matter of doubt in my mind, whether it could not be drained more economically by steam, than by the means usually adopted, although the expence of fuel must certainly be very great. Taking the average of winds, the mills in the winter season do not throw so much water in a week, as they would in one third of the time, if they went with all the velocity of which they are capable. It follows, that one steam engine, with equal powers, would do as much execution in the

course of a season, as three windmills, and consequently a great saving would accrue in the first expense, and afterwards in attendance and repairs."*

* Vide Communications to the Board of Agriculture, vol. iv. p. 52.

IMPROVEMENTS.

EFFECTED BY

MR. WATT, AND OTHERS,

DOWN TO THE PRESENT TIME.

CHAP. II.

Boulton and Watt-Cartwright-Smeaton-Hornblower High-pressure Engine Wolf's Improvements-Rotatory Engines-Kempel — Sadler-Cooke-Bell-crank Engine― Employment of the Steam Engine in North America, and the Colonies-Locomotive Engines.

In the engine usually ascribed to Newcomen, the steam was not employed as an impelling power, but was used for producing a vacuum beneath the piston, which was afterwards forced down by the pressure of the atmosphere; and it was left to the masterly and towering genius of an otherwise obscure mechanic, to quadruple the force of this stupendous machine, and by one step, perfect the labours of the preceding century.

Mr. Watt's attention was first drawn to this subject, by an examination of a small model of