240 



PROCEEDINGS OE THE AMERICAN ACADEMY 



Line Current. 

 4.04 

 340 

 3.04 

 2.66 

 2.26 



Line Current. 



3.77 

 3.23 

 2.78 

 2.51 



Series XI. 



Magnetizing Current = 256 milliamperes. 



Excursion. Line Current. Excursion. 



113 2.00 41 



95 1.53 32 



76 1.25 24 



61 0.94 16 

 54 



Series XII. 



Magnetizing Current = 259 milliamperes. 



Excursion. Line Current. Excursion. 



98 2.29 47 



83 1.87 34 



71 1.53 23 



56 1.19 16 



Series XIII. 



Magnetizing Current = 275 milliamperes. 

 Line Current. Excursion. Line Current. 



3.33 54 2.35 



2.93 46 2.05 



2.63 37 



Series XIV. 

 Magnetizing Current = 310 milliamperes. 



Line Current. 

 3.12 

 2.87 

 2.30 



Excursion. 

 38 

 28 

 12 



Excursion. 

 29 

 23 



These figures show that the change in the amplitude of the vibrn- 

 tion of the diaphragm is approximately proportional to the change in 

 strength of the line current within the limits of line current and 

 magnetizing current used, and with the distance £% inch between the 

 core and diaphragm. Some irregularities in the figures are due to a 

 small variation in the strength of the magnetizing current, which was 

 furnished by a dynamo machine whose speed fluctuated a little. 



