144 
QL (a - Ni 
CSS \ 
~ = 
MY, 
Vig 
Y, 
a 
Us, yh 
Ly, 
Fig. 34 
G gauge; A, piston of tool steel, hardened and tempered blue and ground to size, with sharp edges 
removed, length 3 inches, diemeter .498 inch; this piston works in a central 1/2-inch hole must 
both be cleaned quite free from oil before use; B, screw and two steel washers (No. 3 BA) project- 
ing 1/3Z inch over piston hole to support piston; C, annealed copper cylinder, .5 inch long, .32 
inch diameter; D, corrugated jacket made from sheet brass .004 inch thick, length 5/16 inch, in- 
ternal diameter 5/16 inch, external diemeter 7/16 inch; in addition to centering the coppers, 
these jackets serve to attech paper slips printed with identification numbers; when expanded by 
use these jackets are restored to size by passing through a cone; E, eyebolt, which acts as an 
anvil; when this is screwed home its face is 5 192 inches from the bottom of the gauge; F, eir- 
tunnels 1/4-inch diemeter, communicating with G, four holes, 5 inches long, 1/2 inch diameter, 
closed at the bottr by H, screw stoppers, each pierced by an aperture, 1716 inch diameter, 
which water enters until the internal and external pressures are equal. The body of the 
gauge is of mild steel, the eyebolt of tool steel. 
