ELECTROMAGN'ETIC UNIT OF ELECTRICITY TO THE ELECTROSTATIC UNIT. 605 
Y and W the charges in the condenser and guard ring. Then integrating equations 
(3) and (4), over a time extending from just before the condenser began to charge 
until it is fully charged, remembering that at each of these times — 0, we get 
(6 + y + a) Z + (6 + y) Y + yW — yX = 0 
(a + y + ^) X — (y + /3) Y — yZ — (y + ^) W = 0, 
lence eliminating X 
Zi (h -\-y a— 
MY h 4 - 
r</ (r./ 4- R) 
In our experiments, the battery resistance is very small, being less than 1 ohm, 
while yS is 500,000 ohms, h 200,000 ohms, and y 3000 ohms, thus the third term is 
less than s.ooo. oowl'^^ of the second, and may be neglected, and we get, 
neglecting the battei-y resistance 
If [A] {B} [D] denote the potentials of A, B, D when the condenser is fully 
charged, C the capacity of the condenser, then 
But 
Y..C[(A}-{B}]. 
{A}-{B} _ {A}-{D} 
galvanometer, so that 
„ ^ + 7 ) 
7 
a 
of this equation is 
the steady 
current through the 
Y = -Cz, + 
« + 7)\ 
7 / 
. (5) 
7 - - ^hC ^ 
« + 7 )] 
7 J 
• . (G) 
h 1- 'V -f « - 
0 * 
y + /3 
If the condenser is charged n times per second, the quantity of electricity which 
passes in consequence through the galvanometer per second is nZ. If the galvanometer 
