PHYSICS: S. J. BARNETT 
49 
quasi-stationary motion in a straight line. The general equation is here 
published for the first time: 
p e% Ajf. V/. 
* 6«*c 2 (l--/3 2 ) 3/2 2 xc 4 (l-/3 2 ) 3 6«; 3 (1 - /3 2 ) 2 
, e f x g _ g fxa 
+ 97r C 4 (l-/3 2 ) 5/2 18tt<; 5 (1-/3 2 ) 3 ' 
77 _ e 2 fy _ ft-fif, e 2 f y 
V 6^(1 -/3 2 ) 1/2 2tc*(1-(3 2 ) 2 6tt C 3 (1-/3 2 ) 
e 2 f y a e 2 'f y a 2 
2\2 
where the X axis is taken in the direction of motion, the Y axis is in any 
direction perpendicular to the velocity, a stands for the radius of the elec- 
tron, / is its acceleration, and $ = d/c where v is the velocity of the electron 
and c that of light. The charge e is expressed in Lorentz's unit. It may be 
remarked that the form of this equation, in so far as it involves fi, is in exact 
accord with the Principle of Relativity. 
The analytical reasoning involved in obtaining these results from the 
electrodynamic equations will be given in a paper which has been submitted 
for publication to the Physical Review. 
^Proc. Fifth Int. Cong. Math., 1, 1912, (207). 
2 Relativity and the Ether, Amer. J. Sci., New Haven, 38, 1914, (169). 
ON ELECTROMAGNETIC INDUCTION AND RELATIVE 
MOTION. II. 
By S. J. Barnett 
Department of Physics, Ohio State University 
Communicated by R. A. Millikan, January 19, 1918 
1. If a cylindrical condenser is placed in a uniform magnetic field with 
lines of induction parallel to its axis, and is short-circuited and rotated, to- 
gether with the short-circuiting wire, about this axis, it becomes charged to a 
potential difference equal to the motional electromotive force in the wire, or 
the rate at which the wire cuts magnetic flux. If, however, the condenser 
and wire are fixed and the agent producing the magnetic field rotates, the 
relative motion being the same as before, the condenser does not become 
charged, as was proved 1 by precise experiment in 1912. This is the first 
case in electromagnetic induction in which the observed effect does not depend 
entirely on the relativity of the motion. 
