IV.VERY HIGH-PRESSURE COMPRESSORS.
A. Low-duty Apparatus.-M. Rouquayrol's pump (Fig. 155) is adapted to filling reservoirs of air for divers, of a capacity of something less than a cubic foot, with air under 40 atmospheres' pressure.
The apparatus is composed of two pump-bodies of unequal diameter.
The first has large diameter and long stroke; the second, a much
smaller diameter, and a stroke reduced, so that the volume delivered
by the piston of the large body may be five times greater than
that delivered by the small piston. The air compressed by the
large piston is forced into a small reservoir fortning the upper
portion of the pump-body; and it is in this reservoir that the
small piston carries the pressure from 6 atmospheres to 25. With
an apparatus of four such differential bodies, a pressure of 100
atmospheres may be obtained by man-power. The valves have water-joints,
and all the connections are made with rest accuracy.