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ROYAL SOCIETY OF CANADA 



angles to the test piece. The specimens are turned from material of 

 square section, and one end is passed through the squared hole in the 

 worm wheel, while the other end is secured in a similar way in the 

 weigh lever shown by figure 3. 



This lever consists of a casting L having a central axis M carrying the 

 grip for the specimen, and supported on friction rollers N, mounted in 



Fig. 3a. 



an encircling ring 0. The ring has pivots perpendicular to the central 

 axis, and thin steel plates P, supported from a spindle Q above encircle 

 these and allow the weigh lever to turn about an axis in the plane of 

 the paper, while motion about the central axis is permitted by the fric- 

 tion rollers. This method of suspension permits bending and torsion 

 moments to be applied simultaneously, and any correction for the 

 friction of the pivots can be readily made, although in practice it is 

 found to be so small as to be negligible in general. The weight of the 

 lever arm R and stirrup 8 carrying the weights, is balanced by an 

 adjustable weight T upon the arm U; if the specimen is to be twisted in 

 opposite directions alternately a second weigh lever is fitted on the right 

 hand side instead of the balance weight. The weights are suspended. 



