together at top, and firmly supported there by two diagonal stays, extending from the other end of the boiler, and secured to the flanch, which screws on the end of the boiler. The fly-wheel is situated close to the side of the boiler, and its axis gives motion to the necessary machinery.

The progress of steam navigation has been so rapid, and its importance to a great commercial country like Great Britain must be so obvious, that it has been deemed advisable in our present enlarged notice on the steam engine, to furnish a view of the internal arrangement of the apparatus usually employed for propelling vessels.

A sectional view and plan is represented in Plate IX. the double boiler for generating steam being shewn at a; and b, the chimney by which the smoke is carried from the furnace beneath. The steam-pipe c, is partly shewn in the section, but its course will be better understood by a reference to the plan, in which it is seen to unite the boiler, and cylinders, d d, by the intervention of the valve-box ƒ. The air-pump, e, is worked by the main beam; and the excentric piece for giving motion to the valves is shewn at g. The paddles h h, are usually attached to the main crank by a coupling-box, or toothed wheels, which enables the engineer to throw off either of the propelling wheels at pleasure. It will not be necessary for us to again enter into any detailed description of the steam engine which operates as a prime mover in these vessels, as the construction of the apparatus has been already examined more minutely than the size of our present plate will permit, and the only additional fact connected with the history of this part of our subject, is the attempt that has lately been made to open a communication with India by means of a steam vessel. This indeed, forms a new and important era in steam navigation, and although, owing to some unfavourable circumstances attendant on the supply of fuel, the

first voyage was not performed in so short a period of time as was expected by those who were the most sanguine supporters of the undertaking, yet enough was effected to convince any unprejudiced mind of the practicability of the undertaking.

APPENDIX (A).

List of Patents for the Steam Engine, with an Analytical Account of those more immediately connected with its Improvement and general Application to the useful Arts.*

T. SAVERY, London, July 25, 1698.

THIS patent, which is the first upon record, for an invention in which steam was employed as a prime mover or principal agent in hydrostatics, describes two modes of effecting this very desirable object. In the first, it is used merely to produce a vacuum by condensation; and in the latter, the impellent or expansive force of the steam is made to act upon the surface of the fluid to be raised, and by its pressure in a close vessel, the water is driven up a connecting tube to the required height.

* A complete list of the patent-right inventions connected with this branch of our manufactures, has long been a desideratum; while a reference to the chronological arrangement will shew the progressive improvements that have been effected in its construction. In addition to this, the future experimentalist may derive considerable benefit from the labours of his precursors thus at one view presented to his notice. It is scarcely necessary to add, that a large portion of these exclusive monopolies are of little value beyond that of swelling the fees of the patent office; many of them being precisely the same both in principle and application.

In this engine a vacuum being first formed by the condensation of steam, the water was afterwards raised by the pressure of the atmosphere to a given height from the well into the engine, and then forced out of the engine up the remaining height by the pressure of steam upon its surface. This action was performed alternately in two receivers; so that while the vacuum formed in one was drawing up from the well, the pressure of steam in the other was forcing up water to an elevated reservoir, and by this means a continued stream of water was produced. T. NEWCOMEN and J. CAWLEY, 1705.

This engine has been very fully described in a preceding page; to that, therefore, with a reference to the plate, we shall beg to refer the reader.

J. HULL, London, Dec. 21, 1736.

The mode of propelling vessels by the application of paddle-wheels now so generally adopted, appears to have been originally suggested by this patent. Mr. Hull proposed to employ the atmospheric engine of Newcomen, which, by means of a crank communicating with the working beam, in parted a rotatory action to the wheels or paddles which were placed at the bow of the vessel.

JAMES BRINDLEY, Lancashire, 1759.

The boiler in this engine was proposed to be made of wood and stone, with a cast iron fire-place within side of it, and surrounded on all sides, so as to give its heat to the water. The chimney was an iron pipe or tube, also immersed in the water of the boiler; and this plan Mr. Brindley expected would save a considerable portion of the fuel usually expended.

BLAKEY, 1766.

This patent, which consisted in an improvement upon Savery's engine, was in principle similar to that of Dr.

Papin. In this case a quantity of oil was placed in the receiver, which, rising to the surface, formed a species of piston or float between the surface of the water and the hot steam; thus preventing the continued condensation of elastic vapour, which must necessarily occur in engines upon the original construction.

To effect this desirable object two receivers were to be used, one in the same situation as Savery's, which was to receive the air; and the hot steam, when admitted into it, forced the air to descend by a pipe to the second receiver, which was at the bottom of the well from whence the water was expelled, and proportionably raised in the force pipe.

J. WATT, Birmingham, Jan. 5, 1769.

To the great and comprehensive genius of the late Mr. Watt, and the spirit of rivalry which was excited in the mechanical world on the publication of this patent, which, though the earliest, is certainly the most important of his inventions, may be ascribed the completion of those improvements that have subsequently been effected in the steam engine. This patent, the term of which was prolonged for twenty-one years from the expiration of the original grant, contains the following principles, which, for their importance, we insert in the author's own words :

"First, That the vessel in which the powers of steam are to be employed to work the engine, which is called the cylinder in common fire engines, and which I call the steam vessel, must, during the whole time the engine is at work, be kept as hot as the steam that enters it: first, by inclosing it in a case of wood, or any other material that transmits heat slowly; secondly, by surrounding it with steam or other heated bodies; and, thirdly, by suffering neither water nor any other substance colder than steam, to enter or touch it during that time.