Uf>i i 



PROCEEDINGS OF Mil: AMERIl \N ACADEMY. 



the rod surrounded by the other coils, to the induction at the centre. 

 Thus, suppose for a given constant // we had obtained throws corre- 

 sponding to the central coil alone, and also for this coil when connected 

 in opposition to every one of the other coils in turn. In an actual case 

 we had for Rod B: II' = 59.5, the induction for the central coil was 

 B= 16,56(», leakage between CD and MX was 630, and between 

 CD and X Y 7910, lines of induction per unit cross-section. From 

 these results we get for the actual magnetic induction through M N 



100 



CD 



50 



25 



Curves showing variations in the distribution of magnetic induction in rods 

 No. A and No. B. D = l.'J05 cms. and m = GO. 



15,920 lines, and through X V 8650 lines. Now, denoting tin* />' 

 through the central coil at any time by 100 per cent, we shall have 

 96.3 per cent of this induction passing also through the coil M X, 

 and 52.3 per cent through X V. These two numbers are therefore 

 plotted against li = 16,560. Figures 23, 24, and 25 exhibit all the 

 observations token. The slight zigzag arrangement of the points is 

 due to the fact that the current did not stay quite constant during the 

 time of observing the throws from all the coils on a rod. All the roils 

 have been referred to previously by the same designations, except 

 No. I), which is merely one of the end-pieces cut from the long rod 



