4 Bumstead — Heating Effects produced hy JRontgen Hays. 



approximately 0"002 grm. cm 3 . The two aluminium vanes "were 

 electrically connected by means of a bit of light phosphor- 

 bronze strip. The other details of the suspension are shown 



in figs. 1 and 2. The working quartzfiber, F, is 3 cm long, 

 and is suspended from a glass rod carrying a small magnetic 

 needle, N : as this, in turn, is suspended by a second fiber, F', it 

 may be caused to rotate by means of the bent magnet out- 



