the impossibility of draining them by manual labour, applied to Mr. Trevithick of Camborne in Cornwall, one of the patentees of the high-pressure engine. This ingenious mechanic applied himself with such extraordinary diligence to the subject, that in less than nine months the materials for as many engines were completely ready for their destination. This apparatus, which cost about ten thousand pounds, left Portsmouth in the be ginning of September, 1814, accompanied by M. Uville and three Englishmen, to direct the erection of the machinery.

Mr. Trevithick was afterwards employed to superintend the Royal Mint established at Lima, and on his arrival in South America, was received with such enthusiastic gratitude, that the Lord Warden proposed to erect his statue in massive silver. The engines employed were exclusively on the high-pressure principle, and will be found under his patent in the Appendix to the present work. Indeed this appears to be the only engine likely to act with an advantageous effect, the extreme rarity of the atmosphere in those elevated regions, precluding the economical use of the common engine.

We have hitherto viewed the steam engine, when employed as a substitute for animal force, in giving motion to mills, raising of water, and a variety of other employments, all of which, however, are of a fixed and stationary nature. But,some progress has likewise been made towards the applica

tion of the same power to moveable machinery, and when constructed for this purpose it is called a locomotive engine.

The employment of an internal mechanism to impel waggons on a plane road is of very early date, but the first application of the steam engine to this purpose took place, we believe, in the Royal Arsenal at Paris, towards the close of the last century. From this time till 1802, but little progress appears to have been made in the use of this species of wheel carriage; but about the latter period, Mr. Trevithick commenced a series of expe riments on the use of the high-pressure engine for the above purpose; and this, with some improvements, has since been adopted.

When these engines were first tried, it was found difficult to produce a sufficient degree of re-action between the wheels and the track road, so that the former turned round without advancing the vehicle. This was remedied by Mr. Blenkinsop, who, when he adopted this species of conveyance, took up the common rails on one side of the whole length of the road, and replaced them with rails which had large and coarse cogs projecting from the outside. The impelling wheel of the engine was made to act in these teeth, so that it continued to work in a rack the whole length of the road.

An engine of four horses' power, employed by Mr. Blenkinsop, impelled a carriage lightly loaded at the rate of ten miles an hour, and when con

nected with thirty coal waggons, each weighing more than three tons, it went at about one-third

of that pace.

The application of the steam engine to impel carriages on the public roads, has hitherto been considered as a refinement in mechanics, rather to be wished for, than a matter of reasonable expectation. It has however been stated, that a vehicle of this description is now constructing in Ireland, intended as a stage-coach, and it is added, that when loaded with a weight equal to four tons, it will be enabled to advance at the rate of fifteen English miles per hour. But it must, we think, be sufficiently apparent that the employment of· this species of prime mover on a common gravel road, would be in the highest degree destructive, and a considerable increase in the toll would be the certain consequence.

In proof, however, that the necessity of em ploying an iron track-road for these vehicles is not so serious an objection as at first view might be supposed, more particularly in our mining districts, the neighbourhood of Newcastle alone, affords, within an extent of twenty-eight square miles, more than seventy-five miles fitted for this species of conveyance; and it is a well known fact, that there are many situations in which iron rail-roads might be advantageously employed, in which it would be quite impossible to open a navigable canal.

STEAM NAVIGATION.

CHAP. III.

Introduction and Improvements effected by HullsDuquet-Jouffroy-Fulton-Miller-Symington

-Stanhope-Linnaker-Thames and Clyde boats -Progress of Steam Navigation in America.

THE possibility of employing steam as a moving power in the navigation of vessels, was known early in the last century; its practical application however, on a large scale, has not been fully established above twenty years.

In 1698, Savery recommended the use of paddle-wheels, similar to those now so generally employed in steam vessels, though without in the remotest degree alluding to his engine as a prime mover; and it is probable that he intended to employ the force of men or animals working at a winch for that purpose. About forty years after the publication of this mode of propelling vessels, Mr. Jonathan Hulls obtained a patent for a vessel in which the paddle-wheels were driven by an atmospheric engine of considerable power.

In describing his mode of producing a force sufficient for towing of vessels, and other purposes, the ingenious patentee says, " In some convenient