VITEIFIED BRICK AS MATERIAL FOR COUNTRY ROADS. 31 
Any test at the expiration of which a stave-liner is found detached from the stave 
or seriously out of position shall be rejected. When a new set of liners has been placed 
in position, before being used for testing, the rattler shall be charged with 400 pounds 
of shot of the same sizes, and in the same proportions as provided in Item 9 and shall 
then be run for 1,800 revolutions at the usual prescribed rate of speed. The shot shall 
then be removed and a standard shot charge inserted, after which the rattler may be 
charged with brick for a test. 
No set of liners shall be used for more than one hundred tests. The record must show 
the date when each set of liners goes into service, and the number of tests made upon 
each set. 
The staves when bolted to the heads shall form a barrel 20 inches long, inside meas- 
urement, between headliners. The liners of the staves must be so placed as to drop 
between the headliners. The staves shall be bolted tightly to the heads by four 
f-inch bolts, and each bolt shall be provided with a lock nut, and shall be inspected 
at not less frequent intervals than every fifth test and all nuts shall be kept tight. 
A record shall be made after each inspection showing in what condition the bolts were 
found. 
Item 8. The frame and driving mechanism. — The barrel shall be mounted on a cast- 
iron frame of sufficient strength and rigidity to support it without undue vibration. 
It shall rest on a rigid foundation with or without the interposition of wooden plates 
and shall be fastened thereto by bolts at not less than four points. 
It shall be driven by gearing whose ratio of driver to driven is not less than one to 
four. The counter shaft upon which the driving pinion is mounted shall not be less 
than l^f inches in diameter, with bearings not less than 6 inches in length. It shall 
be belt-driven, and the pulley shall not be less than 18 inches in diameter and 6^ 
inches in face. A belt of 6-inch double-strength leather, properly adjusted, to avoid 
unnecessary slipping, should be used. 
Item 9. The abrasive charge. — The abrasive charge shall consist of cast-iron spheres 
of two sizes. When new, the larger spheres shall be 3.75 inches in diameter and shall 
weigh approximately 7.5 pounds (3.40 kilos) each. Ten spheres of this size shall 
be used. 
These shall be weighed separately after each ten tests, and if the weight of any 
large sphere falls to 7 pounds (3.175 kilos), it shall be discarded and a new one substi- 
tuted, provided, however, that all of the large spheres shall not be discarded and sub- 
stituted by new ones at any single time, and that so far as possible the large spheres 
shall compose a graduated series in various stages of wear. 
When new, the smaller sized spheres shall be 1.875 inches in diameter and shall weigh 
approximately 0.95 pound (0.43 kilo) each. In general the number of small spheres 
in a charge shall not fall below 245 nor exceed 260. The collective weight of the large 
and small spheres shall be as nearly as possible 300 pounds. No small sphere shall be 
retained in use after it has been worn down so that it will pass a circular hole 1.75 
inches in diameter, drilled in an iron plate \ inch in thickness, or weigh lsss than 0.75 
pound (0.34 kilo). Further, the small spheres shall be tested by passing them over 
the above plate, or shall be weighed after every ten tests, and any which pass through 
or fall below the specified weight shall be replaced by new spheres, and provided, 
further, that all of the small spheres shall not be rejected and replaced by new ones 
at any one time, and that so far as possible the small sphere shall compose a graduated 
series in various stages of wear. At any time that any sphere is found to be broken 
or defective it shall at once be replaced. 
The iron composing these spheres shall have a chemical composition within the 
following limits: 
Combined carbon Not less than 2.50 per cent. 
Graphitic carbon Not more than 0.25 per cent. 
Silicon Not more than 1.00 per cent. 
Manganese Not more than 0.50 per cent. 
Phosphorus Not more than 0.25 per cent. 
Sulphur Not more than 0.08 per cent. 
