﻿218 M. W. von Bezold's Investigations on the Electrophorus, 



or glass), and if the latter be sprinkled, a yellow or a red spot 

 will be obtained which will have approximately the same extent as 

 the positive or negative figure formed upon the lower plate. If 

 the cover be raised before the sprinkling, no trace of such a spot 

 will appear upon it. The first case, then, is only the result of 

 an action at a distance. 



Besides the means hitherto mentioned, there is another which 

 in many cases yields very beautiful results. We may investigate 

 the magnitude and direction of the action at a distance in the 

 vicinity of the body to be investigated. We may then draw a 

 conclusion as to the arrangement of the masses in action, as is 

 done in the case of terrestrial magnetism. For this purpose I 

 constructed a small shellac needle 4 centims. in length, at each 

 end of which was a pith ball, and which, like a torsion-balance, 

 was suspended by a cocoon-thread. One ball was negatively 

 and the other positively charged ; and it behaved in respect of 

 electricity like a magnetic needle in reference to magnetism. 

 From the centre of the needle a very light plumb was hung (a 

 cocoon-thread loaded with a minute weight), nearly reaching the 

 plate, which was provided with a network of squares 5 centims. 

 in the side. While now the plumb was brought as accurately as 

 possible over a corner of this net, the direction of the needle 

 could be determined with tolerable accuracy by sighting, and^ 

 thereby the direction of the horizontal components. Observa- 

 tions of the vibrations now gave their magnitude. 

 ' A comparatively small number of such observations places one 

 in a position to construct a series of level- surfaces which give the 

 most interesting conclusions. 



In this investigation I have used this means also, but, for want 

 of space, must defer the communication of the interesting results 

 for more complete publication in another place. For the pre- 

 sent, it maybe sufficient to remark that these results are incom- 

 plete accordance with the theory here developed. 



§ 2. This being premised, I will turn to the chief point of 

 this investigation — to the question of the three layers of electri- 

 city in the cake of an electrophorus. 



Against the assumption of these three layers, objections to 

 the same effect have been urged in another quarter since I com- 

 menced the present investigation. Poggendorff, in a paper 

 " On the manner in which Non-conducting Substances are acted 

 on inductively/'' expresses the view that we must conceive the 

 influencing of non-conductors transferred to the surface — a view 

 which seems to me perfectly correct in the case of the influencing 

 of such bodies. If in the sequel I do not adopt this view, it is only 

 because the facts may all be explained as a simple case of action 

 at a distance, and it is unnecessary to assume that the insulator 



