i 14 Description of Mr. Perkins'' New Steam-Engine, 



steam of constant elasticity is supplied to produce the 

 power. 



Some philosophers are of opinion, that the heat of the 

 portion of water which escapes, is of itself sufficient t© 

 maintain the steam at that high degree of heat and elasti- 

 city with which it reaches the piston, and, consequently, 

 that this engine is nothing more than a High Pressure En- 

 gine. Other persons, however, have supposed, and we 

 confess we are among that number, that the portion of wa- 

 ter which escapes, must necessarily carry off a quantity of 

 heat from the adjoining stratum (the temperature of which 

 may be thus reduced below the freezing point.) But it is 

 more likely, that in virtue of some new law of the trans- 

 mission of heat under the combined conditions of elevated 

 temperature and high pressure, while the water, also, is for- 

 ced to remain in contact with the red hot generator, the 

 whole water in the boiler may be laid under requisition to 

 furnish the discharged fluid with its necessary supply of ca- 

 loric. 



It is almost unnecessary to state, that the motion of the 

 engine is produced by the diiference in elasticity between 

 the steam pressing on one side of the piston, and that press- 

 ing on the other, in the first case, the steam recently pro- 

 duced acts with a force, say of 5001b. on the square inch, 

 while that on the weak side, or that communicating with 

 the condenser, acts with only 70, the difference, or 430lb., 

 being the true power gained. 



When there is a surplus of water in the generator, occa- 

 sioned either by working the forcing pump too violently, 

 or by too vehement a heat, the water will escape by the 

 tube m with a valve above, loaded with 37 atmospheres, and 

 will pass by the pipe 5, 5, 5, into the condenser STXV. 



In order to explain the ingenious manner in which the 

 pipe 4, 4, 4 supplies the generator with water, we must 

 observe that this pipe communicates with the pump L, 

 which is wrought by the engiins. This pump draws the wa- 

 ter by the pipe 6, 6, 6, from the condenser STXV, and re- 

 turns it by the pipe 4, 4, 4 ; that is to say, when the handle 

 M is drawn up, the water rushes into the cylinder of the 

 forcing pump, through a valve in the pipe 6, 6, 6, opening 

 into that cylinder: This valve, of course, instantly closes 

 when the downward stroke of the pump is made, and the 



