254 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Amperemeter 

 Reading. 



0.641 

 1.221 



Ballistic 

 Throw. 



13.94 

 6.65 



Test of Galvanometer. 



Amperemeter 

 Reading. 



13.77 

 13.77 



Ballistic 

 Throw. 



21.46 

 21.44 



10 



B 13,500: first 

 magnetization; O indicates 1-step reversals; 

 X 5-step reversals. 



REVERSALS 5 

 Figure 16. Set V: 



The ballistic galvanometer 

 showed a change of about 

 seven parts in 2150 during 

 the work. The average 1 -step 

 reversal calculated from the 

 two 2-step reversals is 20.85. 

 The current and so the field 

 is slightly greater than for 

 the 1-step reversals. How- 

 ever, it is doubtful if this would account for the difference between 

 20.76 and 20.85 with the flux B, at 13,000 as here. Probably the 

 leakage due to the higher potential produced by the 1-step reversal and 

 not taken into account for 

 this core would make up the 

 difference. At any rate one 

 can be sure that for this par- 

 ticular core at this particular 

 value of B the flux change 

 due to two steps is not less 

 than that due to one. 



Second Set of Data. 



The iron was demagnetized 

 by the transformer. 



Test of Ballistic Galvan- 



ometer. 



Amperemeter 

 Reading. 



13.85 

 13.85 



Ballistic 

 Throw. 



21.76 

 21.75 



Figure 17. Set V: B 13,500: second 

 magnetization; O indicates 1-step rever- 

 sals;- X 5-step reversals. 



The iron was demagnetized by the transformer and the field built up 

 in one step : 



