c 



D = 



to the Electromagnetic Units of Electricity. 309 



X 



'0002 



E 



3UV * 



F = "0013 for first ball of condenser and '0008 for other, 

 as investigated below. 



I = correction for torsion of fibre = 0, as it is eliminated. 



e = constant of electrometer = 17221. 

 G = „ ballistic galvanometer = 19087. 



r = radius of large circle = 42*105 centim. 

 n = number of coils on circle = 1. 



c = constant of electrodynamometer = '0064:54. 

 K = moment of inertia of coil of electrodynamometer 

 = 826-6. 



b = distance of plane of large circle from needle = 1*27. 

 C = capacity of condenser = 50*069 or 29*556. 

 D = distance of mirror from scale = 170*18 centim. 

 w = weight in pan of balance. 



t = time of vibration of suspended coil. 



T = „ „ needle of ballistic galvanometer. 



/3 = deflexion of needle on scale when constant current is 

 passed. 



5 = swing caused by discharge of condenser. 



d = distance of plates of electrometer. 

 N = number of discharges from condenser. 



\ = logarithmic decrement of needle. 



A = correction due to discharges not taking place in an 

 instant. 



« = reading of head of electrodynamometer when constant 

 current is passed. 



The principal correction requiring investigation is A. 

 Let the position and velocity of the needle be represented 

 by 



7T 



x — a sin bt and v = a b cos bt, where b = ™. 



At equal periods of time, t lf 2^, 3^, &c. let new impulses 

 be given to the needle so that the velocity is increased by v 

 at each of these times. The equations which will represent 

 the position and velocity of the needle at any times are, then, 



