404 Prof. W. Cassie on the 



in figs. 2 and 3, their positions can easily be adjusted in 

 Fig. 2. Fig. 3. 



^ c ^ 



M 5C 



any way that may be required. The centre o£ the bar is 

 fixed with a set screw into a short flanged tube, fig. 4, and 



Fig. 4. 



C fig. 2, with two pairs of parallel knife-edges projecting 

 from the sides. These knife-edges rest on double hooks 



fig. 5, which hang from the suspending wires. 



This flanged 



tube with the knife-edges carries also a vertical screw with 

 a nu t — a gravity bob — for adjusting the position of its centre 

 of gravity. 



