31-t Mr. Perkins' Stecim-Engines. 



tent, by being subjected to a very high degree of pressure : 

 which pressure, while it permits the expansion of the molecules 

 of water as ajtuid, prevents their further expansion, or the 

 liquid assuming the gaseous form of steam. 



Instead of the boiler of the ordinary engines, Mr. P. substi- 

 tutes a cylinder, which he terms the generator. This cylinder 

 is made of gun-metal (the most tenacious and least liable to oxi- 

 dation) of about three inclies in thickness, closed at both ends, 

 with the exception of a valve in the top, opening outwards; which 

 valve is loaded with weights equal to the state of the pressure 

 from the expansion of the heated water within. The cylinder is 

 placed vertically in a cylindrical furnace; consequently it be- 

 comes surrounded on all sides with the fire, and soon acquires 

 a tempei'ature of 400° to 450° Fahrenheit. The production of 

 steam is effected by an injecting- pump throwing m water at one 

 part of the generator, which displaces through the valve an 

 equal volume of hot water from the generator. This water, at 

 420°, passing into the induction or steam-pipe, instantly ex- 

 pands into steam, communicates with the working cylinder, and 

 gives motion to its piston, which is placed in a horizontal di- 

 rection, for the more convenient application of its power to ma- 

 chinery. The reciprocal action of the piston opens and shuts 

 the a])ertures of the indiictioii and eduction pipes, by means of 

 rotary valves, as usual in some other engines. But the opera- 

 tion of generating and condensing the steam is effected so in- 

 stantaneously by this engine, that the piston performs about 

 200 strokes in a minute, when the engine is at full work. In- 

 deed, considering the small extent of surface, the power of this 

 engine is almost incredible, the generator containing only about 

 eight gallons of water, and the working cylinder not exceeding 

 two inches diameter, with a stroke of the piston about 12 

 inches in length. The piston ro<l gives motion to a crank and 

 fly-wheel similar to other engines, 



A most decided improvement is also made by Mr. P. in con- 

 densing the steam under a very great degree of pressure, and 

 at a temperature of about 320°, and in this state returning it 

 into the reservoir for the successive supply of the generator. In 

 consequence of this economical arrangement, the space occu- 

 pied by the engine with all its appurtenances, does not exceed 

 an area of six feet by eight. The present model is calculated 

 as equal to a IC-horse power; and Mr. P. considers the 

 whole of the apparatus of sufficient size for a 30-horse engine, 

 with the exception of the working cylinder and piston. The 

 consumption of coal for this engine is within two bushels per 

 day, when at full work. 



All risk of accident is effectually provided against, by the 



following 



