464 



Mr. J* M. Kuehne on the Electrostatic 



moment in the opposite direction whose value is the same as 

 that due to the effect sought for. 



The only other published attempt is that of Whitehead* in 

 1905, following a suggestion by Kolacek. The method of 

 Whitehead's experiment is so crude as to make it entirely 

 incapable of detecting an effect as small as the one sought 

 for. It consists of suspending a block of dielectric (rock- 

 salt) by means of long silk fibres between two oppositely 

 charged plates in the magnetic field of a solenoid, and looking 

 for a ballistic throw when the direction of the magnetic field 

 is suddenly reversed. The motion, as calculated, should be 

 of the order of 10 ~ 6 or 10 -7 cm., and is of course too small 

 to be detected by even the most delicate optical means. 



Present Research. First Method. 



In my own attempt to solve the problem I have employed 

 two distinct methods. The first of these was considerably 

 simpler and more direct in principle, and although it just 

 fell short of yielding the desired solution, yet on account of 

 its bringing the problem more clearly to mind, and also 

 better exhibiting the experimental difficulties in the way 

 of an ultimate and unquestionable solution, I have taken th& 

 liberty to include a brief description. 



The apparatus was constructed as follows : — A charged 

 body in the form of a light hollow cylinder (C, fig. 1) of" 



Fig. 1. 



mica or paper, 6 cm. in diameter, and 6-9 cm. long, open at 

 both ends, was fastened to a long slender rod (R) as axis> 



* Phys. Zeit. vi. p. 474 (1905). 



