36 BULLETIN 373, U. S. DEPAETMENT OF AGRICULTTJEE. 



hard machinery iron and shoukl contain not less than 1 per cent of combined 

 carbon. 



The staves shall be made of 6-iuch medium steel structural channels 27| 

 inches long and weighing 15.5 pounds per linear foot. The staves shall have 

 two holes it inch in diameter, drilled in each end, the center line of the holes 

 being 1 inch from the end and 1| inches either way from the longitudinal center 

 line. The spaces between the staves shall be as uniform as practicable, but 

 must not exceed ^s inch. 



The interior or flat side of each stave shall be protected by a liner f inch 

 thick by 5i inches wide by 19f inches long. The liner shall consist of medium 

 steel plate and shall be riveted to the channel by three ^-inch rivets, one of 

 which shall be on the center line both ways and the other two on the longitu- 

 dinal 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 ins^iected from time to time, and if found loose shall be at once re- 

 riveted. 



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 rattler in 

 which a complete set 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 Item 9, and shall then be run for 18,000 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 stave shall be used for more than 70 consecutive tests without renewing 

 its lining. Two of the 14 staves shall be removed and relined at a time, 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, 3 and 10, 5 and 12, 7 and 14, 2 and 9, 4 

 and 11, 6 and 13, etc., to the end that the interior of the barrel at all times 

 shall present the same relative condition of repair. The changes in the staves 

 should be made at the time when the shot charges are being corrected, and the 

 record must show the number of charges run since the last pair of newly lined 

 staves was placed in position. 



The staves when bolted to the heads shall form a barrel 20 inches long, inside 

 measurement, between head liners. The liners of the staves must be so placed 

 as to drop between the head liners. 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 countershaft upon which the driving pinion is mounted shall 

 not be less than 115 inches in diameter, with bearings not less than 6 inches in 

 length. If a belt drive is used, the pulley shall not be less than 18 inches in 

 diameter and 6^ inches in face. A belt at least 6 inches in width, properly 

 adjusted to avoid unnecessary slipping, should be used. 



