BUCKTON TORSION MACHINE. 201 



of exerting a maximum twisting moment of 4,000 inch- 

 pounds. It is, therefore, suitable for testing specimens of 

 mild steel up to about f in. diameter. 



in. Buckton- Wicksteed Torsional Testing Machine. 



This machine, which is shown on Fig. 94, is similar in its 

 general arrangement to the one which has just been des- 

 cribed. One end of the specimen to be tested is held in the 

 boss of the worm wheel, which is rotated by hand ; the other 

 end is attached to the beam of the machine. This beam 

 rests upon a knife edge in the ordinary way, and carries a 

 poise-weight, which will be seen hanging from the beam. 

 The weight is moved along the beam by means of a screw, 

 rotated by the small hand wheel shown in the photograph. 

 In order that the movement of the beam may be 

 unrestricted, the shaft which is used to communicate the 

 motion to the jockey-weight screw, is connected with the 

 hand-wheel shaft through a Hooke's coupling. The large 

 weight, which is seen hanging from the short arm of the 

 beam at the end of a long rod, is simply an adjustable 

 weight used to balance the long end of the beam and the 

 poise-weight in its initial position. The poise-weight 

 consists of a number of loose discs hung on a vertical rod. 

 By this arrangement the weight can be made variable 

 Avithiu certain limits. 



To the poise-weight carriage is attached a vernier, 

 which slides along a scale fixed to the beam, and in this 

 way indicates the number of inches and the fraction of an 

 inch which the weight, whose magnitude is known, has 

 moved from its zero position. In order that specimens of 

 different lengths may be tested in this machine, and that a 

 specimen which is being tested may be free to vary its 

 length to a small extent, the boss of the worm wheel con- 

 sists of two parts, the boss itself and an inner sleeve, thus 

 making the boss telescopic. The sleeve is free to move 

 longitudinally in the boss, but is prevented from rotating 

 with respect to it by a pair of feather keys. Two smaller 

 sleeves are made use ot to form the connection between 

 the specimen and the larger sleeve, at one end, and the 

 beam at the other. 



An apparatus for taking an automatic record of the 

 test is attached to the front of the beam. The diagram is 

 drawn upon a sheet of paper attached to a brass disc. 

 When the poise-weight is in its zero position, that is, 

 when there is no moment on the specimen, the recording 



