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PROCEEDINGS OF THE AMERICAN ACADEMY 



possible by working at night. In order to indicate the character of 

 our results so far as the deflections of the ballistic galvanometer are 

 concerned, the following values (Table XIII.) are given, from which 

 the deflections in Table XII. are derived. 



TABLE XIII. 



It will be seen from inspection of any one of the various curves last 

 referred to, that as the strength of the field increases, the induced cur- 

 rent increases, and then gradually diminishes. This would of course 

 be anticipated, as the increased magnetization of both the core and the 

 diaphragm increases the strength of field in which the latter moves, 

 and at the same time diminishes the susceptibility of both masses of 

 metal to magnetization. The effect of the former predominates slightly 

 at first, but is overpowered by the latter cause when the magnetization 

 is increased. The Curves 2, 3, 4, 5, 6, show that the addition of the 

 diaphragm causes a greater increase of the induced current at low than 

 at high magnetizations of the core, as would naturally be anticipated. 



Curves 21 and 22 are so nearly alike that they have been placed in 

 separate figures to avoid confusion. It would seem from this coinci- 

 dence that above No. 22 an increased thickness of diaphragm causes 

 little effect. 



A comparison of the curves will show that, with the exception of 

 Curve 31, for which the diaphragm was of ferrotype iron, the value of 

 the maximum induced current is greater according as the diaphragm 

 is thinner ; and also that the strength of field corresponding to this 

 maximum current is likewise greater the thinner the diaphragm. 



