Pers idl 
fteam, and & is the pipe which leads to the condenfer and 
drains the machine, both which muft be open, but in all other 
parts the cafe is fteam tight. a, fig. 3, is a rod which {huts 
the valves as they approach it; and delivers them clofed into 
the fteam vefiel. , 
Wuen the wheel is put into this cafe, and fufpended on its 
axis, fig. 3, the valves within the cafe will open and fill up 
the femicircular vacancy: When the fteam paffes up from the 
‘boiler through the tube it cannot efcape unlefs through this fe- 
micircular vacancy, and as this is filled up by the extended 
valves it muft force them forward in its pafflage to the con- 
denfer, and confequently turn the wheel round. The condenfer 
is worked by a crank in the axis, and a rod 6 ¢ extending 
from it; this caufes a conftant vacuum in that part of the 
femicircular vacancy which lies between the cap d@ and the 
valve e f, on which the fteam preffes; by thefe means a power 
is added to the elafticity of the fteami equal to the preffure of 
the atmofphere, fo that when the force of the fteam is only 
equal to the preffure of the atmofphere, and the valves are fix 
inches fquare, the wheel will be forced round by a power equal 
to 53141b. fufpended at its circumference. 
Arter each valve has performed this operation, another fuc- 
- ceeds it in the like circumftances, and thus the wheel is turned 
round uninterruptedly by a cheap and fimple contrivance. 
A workiNe model of this engine, without the condenfer, was 
exhibited to feyeral members-of the Royal Irifh Academy. 
R 2 
