344 Dr. A. Schuster's Experiments on Electrical Vibrations. 



We shall discuss these explanations in their order. 



1. The explanation given under 1 does not at first sight seem 

 unlikely. We do not know how these electrical vibrations affect 

 the polarization of the battery. They might decrease it for all 

 we know, and thereby cause the phenomena which we have 

 observed. In order to settle this question experimentally, the 

 apparatus was disposed as indicated by the following diagram : *- 



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LLLIe 



The inductor I was taken out of the galvanometer circuit and 

 put into the circuit of the battery. The strength of the elec- 

 trical vibrations passing through the battery was therefore now 

 about 1700 times as great as before. We should expect the 

 effect to be much stronger now if it were caused by any effect 

 of the electrical vibrations on the battery. As, however, the 

 deflection was exactly the same now whether the magnet rotated 

 or not, we may safely conclude that this explanation is not the 

 correct one. I do not say it is proved by these experiments 

 that electrical vibrations do not affect the polarization of 

 the battery. On the contrary^ I think it would be important to 

 make more careful experiments on the subject ; but an inspection 

 of the diagram will show that a small alteration in the electromo- 

 tive force would not be apparent in these experiments. All we can 

 say, therefore, is, that the change in the electromotive force of 

 the battery, if it exists, is not sufficiently large to affect the de- 

 flection of the permanent current if the apparatus is disposed 

 as indicated in the above diagrams. This, of course, is sufficient 

 for our purpose. 



2. We have now to see whether the electrical vibrations can affect 

 the galvanometer- needle in such a way as to produce the effect 

 which was observed, No other cause than the bilateral deflec- 

 tion, discovered by Poggendorff, and mentioned in my paper on 

 unilateral conductivity, is known which could affect the experi- 

 ments. It can be shown that the bilateral deflection is no 

 stable phenomenon ; that is to say, either it does not influence 

 the position of rest of the needle, or it places the needle parallel 

 to the axis of the galvanometer-coil. Experiments were there- 

 fore made in which, instead of taking the first deflection as a 

 measure of the strength of the current, the permanent deflection 

 was measured. It was found that when the needle had come to 

 rest while the permanent current was passing, the position of 

 rest was altered by the rotation of the magnet. 



