EATIO or ELECTROMAGNETIC TO ELECTROSTATIC UNIT 271 



-0002 



.Frrrz -0013 for first ball of condenser and -0008 for other, as investi- 



gated below. 



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

 e = constant of electrometer = 17-221. 

 Q = constant of ballistic galvanometer = 19087. 

 p = radius of large circle = 42-105 cm. 

 w = number of coils on circle = 1. 

 c = constant of electrodynamometer = -006454. 

 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 cm. 

 w = weight in pan of balance. 

 t = time of vibration of suspended coil. 

 7*= time of vibration of needle of ballistic galvanometer. 

 ,3 = deflection of needle on scale when constant current is passed. 

 a = reading of head of electrodynamometer when constant current 



is passed. 



o = swing caused by discharge of condenser. 

 A = distance of plates of electrometer. 

 IV = number of discharges from condenser. 

 X = logarithmic decrement of needle. 

 A = correction due to discharges not taking place in an instant. 



The principal correction, requiring investigation is A. Let the posi- 

 tion and velocity of the needle be represented by 



x = v sin U and v = f b cos bt, where b = / 1. 



At equal periods of time t t , 2/ r 3t t , etc., 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 time are, then, 



