Plate N". 19. 



( 830 ) 

 a =: 0,05867, 6 = 0,2501, 



V 



Observed. 



Calculated 

 I by R. 



Dili'. 



Calculated 

 bv L. 



Dilf. 



Calculated by 

 R. I L. 



lias been made by Tkouton ^) at the suggestion of Fitz Gekald, and 

 in wliieli it was tried to observe the existence of a sudden impulse 

 acting on a condenser at the moment of charging or discharging; 

 foi- this purpose tiie condenser was suspended by a torsion-balance, 

 with its plates parallel to the Earth's motion. For forming an 

 estimate of the etfect that may be expected, it will suffice to consider 

 a condenser with aether as dielectricum. Now, if the apparatus is 

 charged, there will be (§ 1) an electromagnetic momentum 



2 U 



@ 



\x\ 



(Terms of the third and higher orders are here neglected). This 

 momentum being produced at the moment of charging, and dis- 

 appearing at that of discharging, the condenser must experience in 

 the first case an impulse — & and in the second an impulse + @. 



However Tkouton has not been able to observe these jerks. 



I believe it may be shown (tlioiigh his calculations have led him 

 to a different conclusion) that the sensibility of the apparatus was 

 far from sufficient for the object Trolton had in view. 



Representing, as before, by (7 the energy of the charged condenser 



ij Trouton, Dublin lioy. Sue. Tian.s. (2) 7 (1902), p. 379 (Thi.s paper may also 

 be found in The scientific writing:^ of Frrz (ikr.\ld, edited by L.\rmoh, Dublin and 

 London 1902, p. 557). 



