240 



Mr. A. Mallock. The Physical [June 6, 



AB = r, 



1 = natural length of india-rubber, 



Z 1 = DC = length of do. when attached to pendulum, 

 s = natural sectional area of do., 

 W = weight of pendulum. 



Then q as before being Young's modulus, 



_ Wl^Tpg-T^) 



2 - r*T x V 



Fig. 3. 



The following are examples of the measures thus made : — 

 X = 65-2 in. r = 13'5 in. l Q = 11-2 in. W = 10*2 lb. T = 2-581 sec. 



Soft grey. 

 s = 0*2690. 



Eed. 

 s = 0-2307. 



Hard grey. 

 * = 0-2625. 



Tj. 



h- 



1- 







<?. 



Ti. 





%• 



1 -725 



1-75 



1-72 



|ll-35 



193-1 



1 -788 

 1-784 

 1-791 



J 12 '25 



217-75 



1-315 



1-33 



1-30 



jll-S 



500-7 



