104 
Steam Engine. 
Savaiy, who procured a patent for it in 1705, iii which 
they were all three joined. 
Fig. 2, exhibits a section of Newcomen’s engine : a is 
the boiler, built in brick-work. In the top of the boiler 
is a steam-pipe, c, communicating with the cylinder, b, 
which is of metal, and is bored very truly. The lower 
aperture of this pipe is shut by the plate n, v/hich is 
ground very flat, so as to apply very accurately to the 
whole circumference of the orifice. This plate is called 
the regulator, or steam-cock, and it turns horizontally 
round an axis o, which passes through the top of the boi-» 
ler, and is fitted by grinding to the socket, so as to be 
steam-tight. It is opened and shut by a handle fixed to 
its axis. 
In the cylinder b is a solid piston, p, well fitted into it, 
and made air-tight by a packing of leather or soft rope, 
well filled with tallow ; and for greater security, a small 
quantity of water is kept above the piston. 
The piston-rod d is suspended by a chain, which is 
fixed to the upper extremity of the arched head e of the 
great lever, or working- beam, e f g, which turns on the 
gudgeon f. There is a similar arched head g, at the 
other end of the beam ; to the upper extremity of which 
is fixed a chain, carrying the pump-rod h, which raises 
the water from the mine. 
The load on this end of the beam is made to exceed 
considerably the weight of the piston at the other extre- 
mity. 
At a small height above the top of the cylinder, is a cis- 
tern called the injection-cistern, i. From this descends 
the injection-pipe, k, which enters the bottom of the cy- 
linder, and terminates in a nozzle pierced with holes. 
This pipe has a cock, 1, called the injection-cock. 
At the opposite side of the cylinder, a little above its 
bottom, there is a lateral pipe m, turning upwards at the 
