1903.] On a Charged Condenser moving through Space. 



133 



packed with cotton wool ; these were earthed together with the ball 

 containing the condenser. A plane mirror was attached to the con- 

 denser, this was viewed by means of a telescope and scale, through 

 small mica windows in the zinc coverings. The potential was main- 

 tained by a Wimshurst machine, to the terminals of which was attached 

 a Kelvin- White voltmeter. 



The best conditions under which to make the experiment are cal- 

 culated. These include considerations as k to the time of day and time 

 of year, and azimuth of the plane of the condenser. This calculation 

 is made for both the orbital motion and the proper motion of the solar 

 system. 



The following table gives the final results obtained. These were 

 observations taken after many months of experience with the apparatus 

 and were considered by us as conclusive against there being any such 

 effect as we were seeking : 



The largest observed deflection 0'36 cm. barely exceeds 5 per cent, of 

 the calculated deflection 6*8 cm. 



There are also other observations on the electrostatic effects to show 

 that the deflection observed was a purely capricious action and could in 

 no way be attributed to the relative motion of the earth and the aether. 



There is no doubt that the result is a purely negative one, as in 

 other cases of possible interaction between aether and matter that have 

 been examined. As the energy of the magnetic field, if it exists (and 

 from our point of view we must suppose it does) must come from some- 

 where, we are driven to the conclusion that the electrostatic energy of 

 a charged condenser must diminish by the compensating amount 

 N (u/v) 2 , where N is the electrostatic energy, when moving with a 

 velocity u at right angles to its electrostatic lines of force. 



