310 University Geological Survey of Kaisas. 
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Fig. 82. Improved form of working valve for Cornish pump, showing by-passes for 
the entrance of water, by which the rings of packing are forced against the work- 
ing band, and so make a tight connection. 
working barrel, A, is shown in longitudinal section with the 
valve, B. The pump rod, C, is keyed to the valve casting at 
D,and therefore rises and falls with it. The top of the valve, 
HE, fits upon a turned portion of the rod and is free to move 
independent of the rod. The lower surface of the top, #, is 
turned with a convex spherical surface, and the top of the 
valve body, B, is turned with a concave spherical surface, so 
that the contact of the two surfaces so finished will be practi- 
cally water tight. 
The grooves, F and G, which are shown here in section, 
pass around the upper part of the valve body. Two or four 
channels, as H, are drilled connecting the inside of the grooves 
with the space above the valve. The grooves are fitted with 
square rubber building. 
The operation of the valve is as follows: When the rod 
