180 
Steam Engine. 
be no difficulty in distinguishing my said improvements 
from the improved engine, as to its other common and 
well known component parts. 
1st. If the engine be constructed originally with the 
intention of adopting my said improvements, it ought to 
have two steam vessels of different dimensions, according 
to the temperature or the expansive force determined to 
be communicated to the steam made use of in v^orking 
the engine ; for the smaller steam vessel, or cylinder, must 
be a measure for the larger. For example, if steam of 
forty pounds the square inch is fixed on, then the small- 
er steam vessel should be at least one-fortieth part the 
contents of the larger one. Each steam vessel should be 
furnished with a piston, and the smaller cylinder should 
have a communication both at its top and bottom (top 
and bottom being here employed merely as relative terms, 
for the cylinders may be worked in a horizontal, or any 
other required position, as well as vertical.) The small 
cylinder, I say, should have a communication both at its 
top and bottom with the boiler which supplies the steam ; 
which communications, by means of cocks or valves of 
any construction adapted to the use, are to be alternately 
opened and shut during the working of the engine. The 
top of the small cylinder should have a communication 
with the bottom of the larger cylinder, and the bottom of 
the smaller one with the top of the larger, with proper 
means to open and shut these alternately by cocks, valves^ 
or any other well known contrivance. And both the top 
and bottom of the larger cylinder or steam vessel should, 
while the engine is at work, communicate alternately 
with a condensing vessel, into which a jet of water is ad- 
mitted to hasten the condensation ; or the condensing ves- 
sel may be cooled by any other means calculated to pro- 
duce that effect. Things being thus arranged, when the 
engine is at work, steam of high temperature is admitted 
