292 M. A. P. Sun dell on Galvanic Induction. 



Series 3. 



R = R 1= =7-1^ 



mn=2438, Z=86-l, 



and f= ta] 





Jx. 



J. 



,i — A 



Difference 



z. 



t " \ 

 Calculated. Observed. 



10 



. . 49-63 



153-7 154-5 



-0-8 



15 



. . 49-77 



68-2 68-8 



-0-6 



20 



. . 49*17 



34-8 34-7 



+ 0-1 



25 



. . 49-71 



19-8 19-9 



-0-1 



30 



. . 48-33 



12-2 11-9 



4-0-3 



40 



. . 49-66 



5-5 5-5 







Mean . 49*38 



The differences are not important; the theory is certainly 

 confirmed in a very remarkable manner. Also the accordance 

 of the mean value of J\ is very satisfactory ; for we have found 



in the series 1. 2. 3. 



Jj . . . . 49-95 52-45 49*38. 



The mean value is 50*59, with the probable error +0*636, a 

 small quantity considering the simple means used for the expe- 

 riments. 



4. We will now consider the case in which the integral of the 

 first term in expression (1) disappears. Let the induced circuit 

 turn, about the diameter parallel to the y-axis, 90° from its 

 position in the preceding experiments. Thus the two circuits come 

 into a relative position in which no induction exists. The inte- 

 gral of the first term disappears, because the plane of the secondary 

 circuit divides the primary circuit symmetrically ; and as the 

 #2-- plane divides both the circuits symmetrically, the second 

 term also is of no influence. But if we displace the secondary 

 circuit in the y^-plane so that neither the ?/-axis nor the s-axis 

 passes through its centre or intersects its circumference, the 

 integral of the second term obtains a finite value. In order to 

 show this, we draw through the inducing element ds, the coordi- 

 nates of which may be oc y y i 0, a plane (denoted by P) parallel to 

 the #-axis and containing the centre of the secondary circuit. Thus 

 the plane P divides this circuit symmetrically. We combine the 

 element ds with an element ds i oi the secondary circuit on one 

 side of P. Let the coordinates of ds i be 0, 97, f ; then we find 



and the electromotive force in the first moment 



= -f rikh— nvs cos 6 x ds ds-,. . ... (12) 

 4 r 4 ii 2 * 



To the element 0, rj, £* corresponds another element 0, tj 1} % v at 

 the same distance from the plane of symmetry P, but on the 



