184 Scientific Proceedings, Royal Dublin Society. 



steadiness in its operation. So far as the present observations go, the degree 

 •of sensitiveness falls a little short of that obtained by Whiddington^ for his 

 ultra-micrometer. However, the advantages of using a deflection method 

 would in many cases compensate for a slight lack of sensitivity. I shall, 

 however, reserve for a future occasion a discussion of this point, and of some 

 •other considerations relative to the practical employment of the method. 



' Whiddington, Phil. Mag., vol. xl, Nov., 1920, pp. 634-639. 



