168 



Mr. C. Barus on the Viscous Effect of 



has been drawn clown from a larger diameter and the same 

 state of hardness to an extreme of brittle resilience. The 

 wire of Table VI. finally was first softened by heating to 

 redness in air and then drawn down to brittle resilience. 



Fig. 1. — Apparatus for comparing Viscous Deformation. 



/ 



D 



/ 



7 



f/C(//J£f. *^ 



(i) 



a 



-C 



Ttt 



r¥ 



to 



-I 



D' 



f 



-V 



-B 



Dimensions are given in the tables, and the arrangement ol 

 data is that of the above. 6 and 6' are the temperatures of 

 the drawn and normal wires respectively. The former is 

 constant, the latter (^') at first 30°, and then 100^ ; so that 

 the examination is made at two temperatures, in order to 

 compare corresponding viscous effects of the drawn strain 

 and of temper. As above, § 5, t + 2((^ + 0') = 27r/L, and 

 (0 — 0'')/t is the viscous deformation indicated by the mirror. 



