Current with a Magneto-Telephone Transmitter. 397 



magnet, so far as it alone is concerned, will tend to diminish 

 the induced current, on account of the smaller variation in 

 the strength of the pole due to a given motion of the dia- 

 phragm ; and, third, the nearer approach toward saturation 

 of the diaphragm will have the same tendency. 



The rapid rise in the induced current at the beginning is of 

 course due to the predominating influence of the increasing 

 strength of the field in which the diaphragm moves, as both 

 core and diaphragm are then but slightly magnetized. The 

 subsequent changes in the current must be explained by a 

 consideration of the increasing magnetization of either the 

 core or the diaphragm, or both. 



It will be seen by comparing Tables 1., IE., and III., that 

 the value of the maximum induced current for a given ex- 

 cursion of the diaphragm is approximately the same with all 

 the three cores used, and that the same is true as to the 

 strength of field corresponding to this maximum current. 

 Moreover, saturation curves constructed for the several cores 

 showed that in all cases the magnet wasstill very far removed 

 even from half-saturation when the maxinmm induced current 

 was obtained. From these facts it appears that the degree of 

 saturation of the magnet is practically unimportant, so far as 

 the general results shown in fig. 1 are concerned. 



It remains to obsei've the part played by the increasing 

 magnetization of the diaphragm. Other things remaining the 

 same, as this approaches more and more closely towards satu- 

 ration the increase in the number of lines of force passing 

 between it and the magnet on the approach of the diaphragm 

 to the magnet must become smaller and smaller; and this 

 change w'ill tend to oppose the effect of the increased abso- 

 lute strength of the magnetizing force. The small mass of 

 the diaphragm will evidently cause it to show the effect of an 

 approach to saturation while the core is far below that con- 

 dition. And such an action will clearly explain the observed 

 chanoes in the current strength. 



In order to test this matter still further, the experiment 

 was tried of varying the mass and material of the diaphragm. 



The results are shown by the curves in figs. \, 2, and 3, 

 which are constructed from the data given in Tables I. to X, ; 

 further results oi the same character are given in Tables XI. 

 and XII. 



