Temperature on Modulus of Rigidity of Solid Metals* 401 



pipes. When the oscillation becomes purely torsional, the 

 holder is lowered to its original position ; then the torsional 

 oscillation goes on quite freely. F is an electrical resistance 



To Pyroreter. 



furnace 50 cm. long, consisting of a porcelain tube of 2*5 cm. 

 inner diameter wound round anti-inductively with a nichrome 

 wire. The temperature along the axis of the furnace was 

 so uniform that it did not vary more than 5 degrees over a 

 length of 25 cm. at 600° C, so that the test-wire was always 

 found in this uniform region of temperature. A lump of 

 caolin was smeared on the top of the furnace to prevent any 

 convection current of air. In the case of oxidizable metals. 

 such as iron, steel, and copper, the wire was heated in the 

 atmosphere of hydrogen led into the furnace through a 

 Phil. Mag. S. 6. Vol. 42. No. 249. Sept. 1 921. 2 E 



