ON A CHAKGED ELECTRIC CONDENSER 
MOVINC THROUCII SPACE. 
181 
All the above observations were taken clnring the middle of the day and tlie 
afternoon. 
There seems to be no change of deflection with change of sign, and l)y comparison 
with previous results there seems to be no bias one way or the other. 
From experience gained with the apparatus, the deflections observed would appear 
to be attributable to small sparks or discharges taking place inside or over the 
condenser, causing slight heating and consequent perturbation of the surrounding 
air. This is further suggested by the fact that when the condenser employed had 
become damaged by falls and other vicissitudes, so that audible sparkings occurred, 
the perturbatioDS became so great as to prevent all possibility of observation. 
There is no doubt that the result is a purely negative one. As the energy of tlie 
magnetic field, if it exists (and from our present point of view we must suppose it 
does), must come from .somewhere, we are driven to the conclusion that the electro¬ 
static energy of a charged condenser must diminish by the amount N {ujvf, when 
moving with a velocity u at right angles to its electrostatic lines of force, where N is 
the electrostatic energy. 
tsNOltlMB 
