The cylinder, in which a well-fitting piston worked, was provided at its lower end with two valves.
In a particular case where the boiler pressure was maintained constant at 130 lb per square inch, and the cut-off was approximately 20% of the stroke, the values c =55 and b=o 031 were deduced, from which it will be found that the value of the piston speed corresponding to the maximum horsepower is 887 ft.
On again F J J raising the piston the valve E opens ?g G admitting more liquid whilst F re- mains closed.
The air inside is compressed in consequence and during an upstroke of the piston this air tends to regain its original volume and so expels the water, thus bringing about a continuous supply.
P. Joule with the perforated piston and with the friction of water and mercury.