FirzceraLp— Quantity of Energy Transferred to Ether by a Variable Current. 59 
Hence the sum of the squares of these integrals is 
=a. 4 (1+ PR), 
So that the average value of 7’ is 
T = (nai,? eee ih (Sf + eR) © dedyde. 
If this be integrated over the sphere of which # is a radius, it will give the 
average energy on that sphere. 
Now, p=Rksn¢d, dedydz= Ff’ sn ddd.db.dR. 
So that if we assume F& constant, the average superficial energy is 
Aer La, ja Ar 
(wa%,).g (1 + OR) aa, 
Halt (ees al 
(aa? ty) °—- (es z) 
Now, one part of this is independent of the size of the sphere, while the other 
part varies inversely as the square of the distance from the current. It is evidently 
only the first part of the energy that is really saa and if we assume that it 
ll 
moves with the same velocity as the waves, = Te we find that the energy 
radiated per second is 
ee Ae Qn / Kp . 1 
= (1a?%)’. —, oras /= if VY=—— 
6 / Kp dh V Kp 
yp Opa 
= (7a?) ‘a 
: ', this value can be got by considering the dimen- 
sions of the quantities involved, if we assume that the energy radiated is propor- 
tional to the square of the moment of magnetism of the radiating particle (za*7,), 
which is evidently the case from the value of the energy in the form Fu+ Gv+ Hu, 
as F, G, H and u, v, w are all proportional to this moment. 
If we calculate the amount of this energy we find that it is very small, except 
Except for the coefficient 
A 
for very rapid vibrations indeed. For = = 2604.p., while 
4 
V? 26 x 10"; therefore = =10-” g.p.; 
