AND SURFACE CoNDKNSKR. 349 



fire through a pipe leading into the ash-pit. This, however, 

 will not be necessary where there is a chimney high enough to 

 create a strong draught. In respect to proportions, niy improved 

 steam-engine admits of considerable latitude, and it will be 

 sufficient direction to any practical engineer to say that for 

 engines working with steam of 120 Ibs. to the inch, used expan- 

 sively till it be nearly reduced to atmospheric strength and 

 then condensed, a 10-horse engine may have a fire-place of 

 20 inches diameter, the flue at the top 10 inches diameter, and 

 a boiler of 20 feet high ; a 60-horse engine, a fire-place of 

 36 inches diameter, a flue of 16 inches diameter, and a boiler 

 of 20 feet high. In boat-engines, and in other cases where 

 height cannot be allowed, the diameter must be increased. The 

 thickness of the two tubes constituting the boiler sides of a 

 10-horse engine may be |th of an inch, that of a 60-horse a 

 quarter of an inch, and so in proportion for engines of other 

 power. The tubes constituting the condenser and inner tube of 

 the air-vessel may in all cases be ^th of an inch thick. The 

 outer tube may be fths of an inch thick, to afford stability to 

 the working cylinder, the blowing cylinder, and the forcing 

 pump fastened to this tube, and as an ultimate perfect barrier 

 against explosion. The respective distances of the other tubes 

 constituting the outside of the boiler, the condenser, and air- 

 \< -el, will be the same as hereinbefore given, and therefore 

 their diameters will depend upon the diameter of the fire-place. 

 The cap-piece in small engines may be half an inch thick, and 

 in large engines an inch. The bottom of the ash-pit and bottom 

 of the boiler must have about half an inch of thickness for 

 every foot diameter, or they may be cast with ribs to afford 

 equivalent strength. The fuel is supplied through a door in 

 the, flue, at the top of the boiler, consisting of coke or coals the 

 least liable to swell with heat. The flue may be filled to about 

 one-third of the height of the boiler, and the water fill about 

 three-fourths of the boiler, leaving one-fourth for steam. 



Having clearly explained my improved steam-engine so that 

 any person competent to make a steam-engine can from this 

 description understand my invention and carry the same into 

 effect in as beneficial a manner as myself, I proceed to observe 



