Dr. A. Schuster's Experiments on Electrical Vibrations. 343 



than it had been before. The electrical vibrations were, of 

 course, much stronger now ; but each of them taken separately 

 would have produced about the same deflection of the galvano- 

 meter. The galvanometer had no damping-arrangement. The 

 needle, therefore, never was entirely at rest ; and, accordingly, 

 the first deflection could not be measured. Five successive elon- 

 gations were taken, and the position of rest calculated from these 

 elongations. As the observations necessarily extended over a 

 much greater length of time, they were less accurate. The result 

 is given in the following Table. The first column gives the first 

 deflection observed when the magnet was not rotating; the 

 second column gives the ratio n of the difference in the first de- 

 flections to the first deflection observed when the magnet was not 

 rotating. 



First deflection 





observed when 



n. 



magnet was quiet. 





248 



0-076 



205 



0069 



164 



0053 



124 



0-070 



99 



0046 



With the exception of the last observation but one, therefore, 

 the effect decreases more rapidly than the current. 



III. Discussion of Experiments. 



We shall have to discuss now whether these experiments can 

 be explained in any simple way or by any known causes. At 

 first sight three possible explanations suggest themselves ; and 

 we have to see whether one of them, or several of them taken 

 together account satisfactorily for the different experiments, 

 before we assume that we have to do with a new set of pheno- 

 mena. We might assume : — 



1. That the electrical vibrations affect the electromotive force 

 of the battery ; 



2. That the electrical vibrations affect the magnetism of the 

 galvanometer-needle so as to increase the deflection of the per- 

 manent current; 



3. That the permanent current affects the magnetism of the 

 rotating magnet in such a way as to increase its momentum 

 while the current in one direction is passing, and to decrease it 

 while the current in the opposite direction is passing. The two 

 opposite currents induced by the magnet would therefore not 

 counterbalance each other, but one would be stronger than the 

 other. 



