OP ARTS AND SCIENCES. 243 



Series XXII. 

 Line Current = 3.55 milliamperes. 



It will be noticed from the data given in the tables and the curves 



© 



that with the core of the magnet at a distance of ,\ inch fr 



iiuGL at ci UKiiamc ui 7v; 



I-OIU 



the diaphragm, a first maximum of the excursion is reached with a 

 magnetizing current not far removed from 160 milliamperes. while 

 with a distance of 3 'o inch the maximum excursion occurred when the 

 magnetizing current had a value of about 225 milliamperes. 



With the diaphragm thus close to the magnet, it was observed, as 

 will be seen from the figures, that, after the amplitude of the vibration 

 of the diaphragm had begun to decrease owing to the approach of the 

 diaphragm toward saturation, there was a later increase of this ampli- 

 tude, which rose even to an amount greater than for any previous 

 value of the magnetizing current. This was "brought about by the 

 motion of the diaphragm towards the pole, the diaphragm assuming a 

 new position of equilibrium under the increased pull of the magnet. 

 The effect of increased proximity of the diaphragm to the core more 

 than makes up for the opposing effect of a closer approach of the dia- 

 phragm toward saturation. 



A separate study of the variation in the excursion after the second 

 rapid rise began was made by using the strongest possible magnetizing 

 current below that which pulled the diaphragm into contact with the 

 core, viz. 204 milliamperes, and varying the line current, the excur- 

 sions being measured as before. The results are given in Table \ '., 

 and shown graphically in Figure o. 



TABLE V. 



Series XXII a. 

 Magnetizing Current = 204 milliamperes. 



