32 



ART. 4. — K. nOXDA AT^D T. TERADA. 



reading off the deflexion. Usually n' did not exceed 7 divisions 

 of the scale, wliile ^ was greater than 90 divisions. 



To prevent shocks by loading, the face of the initial weight 

 was covered with a mat of cotton wool. The wire to be tested 

 was surrounded by a tube of paper to prevent disturbance due to 

 air-current. 



Denoting the weight, by which the elongation dl—ol' is pro- 

 duced, by P, we have for the coefficient of elasticity 



F 



E= 



A 



dl-dV 



where A is the section of the wire. P in our experiments was 

 100 grams, which gave a deflection of more thnn 00 divisions of 

 tlie scale. To test the working of the present apparatus, 10, 50 

 and 100 grams were loaded Vv'ith the following results : — 



TABLE XXII. 



Thus the proportionality is nearly satisfied up to 100 grams ; 

 this also shows that the friction at different parts of the arrange- 

 ment is negligibly small. 



The coefficient of elasticity differed slightly for different 

 initial tensions, and moreover underwent more or less hysteresis 

 due to the previous load. In our experiments, the weights were 



