p. LECOMTE DU NOUY 



523 



Fig. 1. 



The tension of the wire can be adjusted. The torsion is con- 

 trolled by a gear, which moves very slowly. The dial shown in 

 Fig. 1 is attached to the wire and turns with it. A fixed needle 

 indicates the angle of torsion. The apparatus described is home- 

 made, and would be greatly improved by using a large dial and a 

 worm-gear for controlling the torsion. 



