Steam-Engines, 1832.

"Now know ye, that in compliance with the said proviso, I, the said Richard Trevithick, do hereby declare the nature of my said invention, as regards the improvement or improvements on the steam-engine, to consist in interposing between the boiler and the working cylinder, in a situation to be strongly heated, a long pipe formed of a compact series of curved or bent pipes, which I denominate the dry pipes, or steam-expanding apparatus, through which dry pipes I cause the steam, after it has been generated in the boiler in contact and consequently saturated with water, to pass with very great velocity, in order that it may imbibe a copious supply of additional heat without any addition of water, and by this additional heat to be expanded into a greater bulk of steam, of about the same expansive force that it had acquired in the boiler, by which means I obtain a greater volume of steam for use in the working cylinder than the boiler alone would supply; and in order still further to augment this volume of steam, I place the working cylinder within a case constituting a part of the flue or chimney, that the cylinder may be kept considerably hotter than the steam employed in it by absorbing a great portion of the heat remaining in the flue after having heated the boiler and the dry pipes, which heat would otherwise pass away out of the top of the chimney and be wasted, but by this arrangement is converted into a useful power by further expanding the steam in the cylinder.

"And I do further declare, that in carrying this part of my said improvement into effect, I do not find it necessary to confine myself to any particular form of boiler, or arrangement of pipes, in which the steam is to be heated; but by preference, as being very compact in form, and economical of fuel in using, I make my boiler of a number of upright pipes, standing upon and communicating with a tubular ring placed around and a little below the fire-grate; these pipes all surround the fire-place, except two or three, the lower ends of which are elevated above the fire-door, but connected at the bottom by a branch pipe united to one of the adjoining upright pipes, thereby leaving an opening or place of access to the fire. These pipes all extend upwards to the height of several feet, according to the quantity of steam required to be raised, combined with local convenience, for it is obvious that the power of this boiler to raise steam may be increased either by increase of the length of the pipes, of their diameters, or of their numbers. And I do lay upon the upper ends of the pipes hereinbefore described and connect with them a tubular ring similar to that upon which the pipes stand, the two rings and the upright pipes forming together a vessel in which water has free communication by means of the bottom ring to stand at the same level in all the pipes, and the steam has free communication to pass from all the pipes into the upper ring; and I do, for the sake of obtaining great heat, place my system of dry pipes over the fire, and within the circular row of upright pipes of the boiler hereinbefore described; and I form my dry pipes in pairs, each pair constituting the figure that is well understood by the term inverted syphon; and I unite several of these syphons together by short bent pipes at the top, so as to constitute one long zigzag pipe, through which the steam must successively pass down and up the alternate legs of each syphon with great velocity, necessary for the rapid absorption of heat in its passage from the boiler to the working cylinder of the engine, the working cock, valves, or slide of which being united by a pipe of communication with that leg which is last in the succession of syphons; and I unite the first in succession of these inverted syphons with the upper tubular ring of the boiler by means of a bent pipe, in which a throttle-valve or cock is placed in order to limit the supply of steam, that it may have space in the dry pipes and working cylinder to expand in proportion as it receives additional heat; and I fix a safety-valve in communication with the boiler, and another in communication with the dry pipes; and I place around outside the boiler, at a small distance from the upright pipes, two cylindrical casings, one within the other, and fill up the space between the two casings with sand, ashes, or other material which conducts heat but slowly; and I close up the upper end of the casings over the boiler and the dry pipes with a covering in the form of a dome, and out of this enclosure I make the flue to pass to and around the working cylinder of the engine, whence the flue carries the smoke and little remaining heat away in any convenient manner; and I make my boiler-pipes, rings, and casings by preference of iron or copper, and my dry pipes of copper or other strong metal not liable to rapid oxidation by heat when in contact with steam; and I supply my boiler with water by means of a forcing pump, so adjusted as to keep the water of the proper height.

"And I do hereby further declare, that the nature of my said invention, as regards the improvements in the application of steam-power to navigation, consists in the drawing of water into a receptacle placed near within the stern of the navigable vessel, which water is drawn in through an orifice in the stern with a moderate degree of velocity in the direction of the course of the vessel, and ejected with great force and speed in a direction opposite to the course of the vessel through the same orifice, reduced to about a quarter of the area by means of a valve opening as the water enters, and partially shutting as the water is ejected; and thus I propel the vessel with great force, derived from the recoil of the water set into rapid motion in a direction opposite to the course of the vessel, the rapidity of the jet of water to be at least equal to double the required speed of the vessel to be navigated.

"And I further declare, that by preference I effect the purpose of receiving and of ejecting the water, and of deriving a motive force from its recoil, by means of a large vertical cylinder of cast iron or other metal, closed at both ends, in which a piston is forced up and down by a piston-rod sliding through a stuffing box in the lid, which piston-rod receives its motive force from a steam-engine; and I fix a tube into the after side of this cylinder, near the bottom, in communication with the space below the piston, which tube leads through the stern of the vessel, as low down as practicable, and opens on one side of the rudder; and I fix another tube into the after side of this cylinder, near the top, in communication with the space above the piston, which tube also leads through the stern of the vessel, as low down as practicable, but opens out on the other side of the rudder; and I place in the mouth of each of these tubes a valve opening inwards, to allow the water free entrance, equal to the bore of the tube, and partially shutting when the water is ejected, so as to reduce the opening through the stern to about one-fourth of the area of the tube.

"And I do hereby further declare, that the nature of my said invention, as regards the improvement in the application of steam-power to locomotion, consists in the application of such a boiler, together with the expanding apparatus as aforesaid, to locomotive engines, whereby a diminished weight of boiler and quantity of water and fuel is obtained; and in farther compliance with the said proviso, I, the said Richard Trevithick, do hereby describe the manner in which my said invention is to be performed, by the following description of its various parts in detail, reference being had to the drawing annexed, and to the figures and letters marked thereon, that is to say:—

"Description of the Drawing. [Plate XVII.]

PLATE 17.
TREVITHICK'S PATENT BOILER AND ENGINE, 1832.

London: E. & F.N. Spon. 48, Charing Cross. Kell Lith. London.