174 Description of Mr Perkins’s New Steam-Engine. 
Fahrenheit is thus applied to the generator, which is entirely filled 
with water, The valves in the tubes m, n, which are steel cylin- 
ders working in hollow steel-pipes, are loaded, the one with 37, 
and the other with 35 atmospheres ; so that none of them can 
rise till the heat creates a force greater than the least of these 
weights. 
Let us now suppose, that, by means of the compressing pump 
L, whose handle M is wrought by the engine, water is forced 
into the generator ; this opens the valve above n , loaded with 
35 atmospheres, and instantly a portion of the heated and com- 
pressed water flashes out in the form of steam of high elasticity, 
and of a temperature of 420°; and communicating by the steam- 
pipe 2, 2, 2, with the valve-box V, it enters the cylinder PP, 
lying horizontally, and gives motion to its piston PQ, which 
performs 200 strokes in a minute, and drives a crank R, which 
gives a rotatory motion to a fly-wheel, as seen in the figure *. 
When the eduction-valve is opened, the steam, after having 
produced its stroke, is carried by the eduction-pipe 3, 3, 3, into 
the condenser STXV, where it is condensed into water at a tem- 
perature of about 320°, and under a pressure of 5 atmospheres ; 
from thence, by the pipe 6, 6^ 6, it is drawn into the pump L, 
whence it is forced along the pipe 4, 4, 4, to the generator, thus 
performing a complete circuit. 
The forcing-pump acts with a pressure exceeding 35 atmo- 
spheres ; consequently, when the water received in it from the 
condenser is urged into the generator, it must expel a portion 
equal to itself in volume: this portion, as above described, flashes 
instantly into highly elastic steam. The forcing-pump, too, is 
so contrived as to act with a steady force, and, consequently, 
the expelled water must be driven from the generator in a steady 
current, and thus steam of a constant elasticity is supplied to pro- 
duce the power. 
Some philosophers are of opinion, that the heat of the por- 
tion of water which escapes, is of itself sufficient to maintain the 
steam at that high degree of heat and elasticity with which it 
* The parallel motion represented at PQ, is not the correct one used by Mr 
Perkins. The piston-rod is connected by a flexible joint, with a sort of carriage 
with four wheels at each end, and working in a strong horizontal box of steel. 
