218 Steam Mngihh. 
cooled by the injection water, as in Newcomen’^ or the 
atmospheric engine. 
2dly. Making an approach to a vacuum by pumping 
out the air, w^hich always, to a certain degree, accompa- 
nies the steam, and by its elasticity re- acts against the 
under side of the piston. 
3dly. Keeping the outside of the cylinder in which the 
piston works, hot, by the intervention of steam between 
it and a casing. 
4thly. The parallel motion of the beam, by which the 
stiff up^vright rod attached to the beam and the piston 
presents its perpendicularity during the stroke. 
5thly. Depressing the piston by steam instead of the 
atmosphere. 
6thly. Keeping the top of the piston hot by the casing 
between the piston and the outward air, so that the steam 
let on above, is of the same temperature always as that 
below. 
7thly. Consuming the smoke of the fuel, by making: 
it pass through and over the red-hot coals. 
8thly. Supplying the boiler with the hot injection 
water. 
9thly. The application of the steam pipe above the 
water in the boiler, to asc ertain when the water is too high : 
and the mode of opening the valve of the feeder, when 
the water sinks too low in the boiler ; by the floating 
stone instead of the ball-cock. 
lOthly. The circular motion communicated to the fly 
wheel by means of the sun and planet wheels. 
Mr. Caitwright’s improvements consist in 
1st. The method of giving the necessary perpendicu- 
lar motion to the piston rod. 
2dly. The condensing the steam by expanding it in a 
tliin surface between metal balls cooled with water inside 
and outside, so that a great surface of steam is exposed 
