172 APPENDIX. 



of water is withdrawn from the condenser, or hot-water cistern, and projected through the 

 nosle over the upper plate and cups, when it is instantly and completely vaporised. The 

 pump has a cock or valve by which to adjust the supply of water, and a hand-pump is pro- 

 vided to start the engine, and increase the facility of commanding it. Before arriving at the 

 nosle the water is heated, in a pipe or vessel exposed partially to the fire, in order that it may 

 not diminish the elasticity of the steam already formed, and that it may more readily vaporise. 

 The heat from the fuel that has not been absorbed by the mercury passes around a steam 

 chamber, by which means the steam is heated and expanded considerably after its formation, 

 and thence proceeds from the upper part of the chamber to the cylinder valves in the usual 

 manner. This exterior or flue casing is covered by a non-conducting substance, as are also 

 the steam pipes, cylinder, &c. The above construction is expressly intended for working the 

 steam expansively, the pressure being in general about ten fts. per square inch above the 

 atmosphere, and the steam cut off from the cylinder at about a third of the stroke. The 

 acting machinery of the engine is on the ordinary construction, and the packing of the piston 

 and valves are metallic. 



The process of CONDENSATION consists in abstracting the heat from the water of injection, 

 by bringing it in contact with a sufficient surface of metal, exposed externally to cold water in 

 any efficient manner, and re-injecting the water thus cooled amidst the steam. 



The air-pump withdraws the warm water from the condenser into the hot cistern in the 

 usual manner, and the water is passed from thence by the pressure of the atmosphere (a partial 

 vacuum existing in the condenser) into a copper pipe or worm, exposed to cold water in a 

 cistern constantly supplied by a pump or otherwise. The refrigerating pipe terminates 

 within the condenser, and the water having been previously cooled by its gradual progress 

 through it, enters into immediate contact with the steam, and instantly reduces it to the liquid 

 state. A valve is placed at the end of this pipe within the condenser, and is connected by a 

 rod and lever to a float in the hot cistern, which prevents all the water from being drawn out 

 of the latter at any time, and which valve also serves to disperse the water amidst the steam. 

 It is further adjustable by hand. Before starting the engine, a sufficient quantity of water is 

 provided to ensure the circulation, by entirely filling the refrigerating pipe and part of the hot 

 water cistern. The surface of this pipe (or other vessel substituted for it), when the condenser 

 is employed with the vaporiser before described, and the steam worked expansively, should 

 be about four square feet per horse power. 



A still is provided to furnish a supply of pure water, to replace any loss by leakages, and is 

 attached to the flue of the vaporiser, in which latter the use of water containing salt or other 

 impurities is inadmissible. 



This process of condensation is equally applicable to the ordinary engine with boilers. 



