36 BULLETIN 1216, V. & DEPARTMENT OF AGBICU1/TUBE. 
free from lost motion. The distance from the end of the shaft 
or trunnion to the inside face of the head shall he 151 inches in 
the head for the driving end of the rattler, and 11§ inches for the 
other head, and the distance from the face of the hubs to the in- 
side face of the heads shall he 5j inches. 
The heads shall be not less than three-fourths inch thick, nor 
more than seven-eighths inch thick. In outline, each head shall 
be a regular 14-sided polygon inscribed in a circle 28g inches in 
diameter. Bach head shall he provided with flanges not less 
three-fourths inch thick and extending outward 2\ inches from 
the inside face of the head to afford a means of fastening the 
staves. The surface of the flanges of the head shall be smooth 
and give a true and uniform hearing for the staves. To secure 
the desired true and uniform bearing, the surfaces of the flanges 
of the head shall he either ground or machined. The flanges 
shall be slotted on the outer edge, so as to provide for two three- 
fourth-inch holts at each end of each stave, the slots to be thirteen- 
sixteenths inch wide and 2f inches center to center. Each slot 
shall he provided with a recess for the bob head, which shall act 
to prevent the turning of the same. Between each two slots 
there shall be a brace three-eighths inch thick, extending down 
the outward side of the head not less than 2 inches. 
There shall be for each head a cast-iron head liner 1 inch 
in thickness and conforming to the outline of the bead, but in- 
scribed in a circle 28$ inches in diameter. Tins bead liner shall 
be fastened to the head by seven fivo-eighths-inch cap screws, 
through the head from the outside. Whenever these head liners 
become worn down one-half inch below their initial surface level 
at any point of their surface they shall be replaced with new 
ones. The metal of these head liners shall be hard machinery 
iron and should contain not less than 1 per 'cent of combined 
carbon. 
' The staves shall be made of 6-inch medium-steel structural 
channels, 27£ inches long and weighing*15.5 pounds per lineal 
foot. The staves shall have two holes thirteen-sixteenths inch 
in diameter, drilled in each end, the center line of the holes 
being 1 inch from the end and 1§ inches each way from the 
longitudinal center line. The spaces between the staves shall 
be as uniform as practicable, but shall not exceed five-sixteenths 
inch. 
The interior or flat side of each stave shall bo protected by 
a liner three-eighths inch thick by fU inches wide and 10| inches 
long. The liner shall consist of medium-steel plate, and shall 
be riveted to the channel by three one-half-inch rivets, one 
of which shall be on the center line both ways and the other 
two on the longitudinal center line and spaced 7 inches from 
the center each way. The rivet holes shall be countersunk on 
the face of the liner and the rivets shall be driven hot and 
chipped off flush with the surface of the liners. These liners 
shall be inspected from time to time, and if found loose shall be 
at once rorivefod. 
Any test at the expiration of winch a stave liner is found 
detached from the stave 4 or seriously out of position shall be 
rejected. When a new rattler, in which a complete sot of new 
staves is furnished, is first put into operation, it shall be charged 
with 400 pounds of shot of the same sizes, and in the same pro- 
portions as provided in section 4. and shall then be run for 18.000 
revolutions at the usual prescribed rate of speed. The shot 
shall then he removed and a standard shot charge inserted, after 
which the rattler may be charged with brick for a test. 
No Stave shall he used for more than 70 consecutive tests with- 
out renewing its lining. Two of the 14 staves shall be removed 
and rellned at a lime in such a way that of each pair, one falls 
upon one side of the barrel and the other upon the opposite side, 
and also so that the staves changed shall be consecutive but not 
contiguous; for example. 1 and 8. \\ and 10. 5 and 12. 7 and 14. 
