425 
clearly be proportional to the angular velocity directly. Un- 
fortunately the experiments were always made with the same 
angular velocity. 
From Thermodynamic considerations we can show that the 
rise of temperature due to compression is 
Cc Cod Ce; 
At = 2-1) sated Gos ane 
f (¢ pe Jdodm 
where c.¢ are specific heats at constant pressure and volume 
respectively, ¢ is the compression, « the coefficient of expansion 
for heat, and = the external work done per unit of mass. 
It can be shown that the displacement at any point is 
given by 
Aw’a'm m 
, E= 15 r=L. .1, sayy 
where d = coefficient of resistance to form, 
a =radius of disk, 
m= mass of unit of volume. 
Work done at any point per unit mass 
olen dé\? el dy 2m ,, 
= n= ae +f bm XW Ee 
Pl de Baer 
The compression ¢= ae + aay lhe 
C ot Wm 
whence ar={($-1) 2 - FS 
In the experiments 
w = 2500 rev. in 30” = = : 
a=7'5 in. ='1905 metres nearly, 
J = 424 gramme-metres. 
