M. A. F. Sundell on Galvanic Induction, 295 



As in comparison with the great distance between the inducing 

 coil and the magnetometer, b x can be neglected, for b we may- 

 assume 26 = -12-40 + 12-25= —0-15, or b- —0-08, a quantity 

 certainly within the limits of errors of observation. Thus these 

 experiments confirm that the second term in the formula of in- 

 duction is very small compared with the first term. 



5. When the aether in a circuit is put in motion, its repul- 

 sive force on the surrounding aether-molecules is changed ; and 

 these are moved to a new position of equilibrium. Also the 

 aether in a circuit placed in the neighbourhood of the former is 

 momentarily moved ; that is to say, a secondary current is excited 

 in it. When the inducing current ceases, the surrounding 

 aether and that in the secondary circuit return to the original 

 position of equilibrium ; and thus a secondary current of oppo- 

 site direction is produced. It is known that secondary cur- 

 rents of the same intensity as those which are excited by esta- 

 blishing or destroying the inducing current, the circuits being in 

 any one relative position, are also produced when the circuits 

 are brought into this position from another (in which no induc- 

 tion is performed by completing or breaking the primary circuit), 

 or vice versa, from the former into the latter position. The new 

 theory explains this in a very simple manner. Suppose the in- 

 ducing current is established ; then the aether in the secondary 

 circuit is displaced from its original position of equilibrium. We 

 can restore the original equilibrium in two ways. The cause of 

 perturbation is removed either by breaking the inducing cur- 

 rent or by changing, in a suitable manner, the relative posi- 

 tion of the circuits, for example, by making the distance be- 

 tween them very great. Further, by bringing the circuits 

 from this latter position into the former, the aether in the se- 

 condary circuit is disturbed in the same manner as by esta- 

 blishing the inducing current in the original position. The 

 velocity of the relative motion has no influence on the total 

 intensity of the induced currents. 



In connexion with the experiments related, the following 

 were made in order to ascertain the agreement in results of 

 the two methods of induction. The coils last used were placed 

 horizontally the one upon the other, so that their centres were 

 on the same vertical line. In this position the primary circuit 

 was (once) completed or broken, and the intensity of the excited 

 secondary currents was noted. Then, the primary circuit being- 

 closed, the secondary coil was vertically raised to a position in 

 which no inducing effect was observed on establishing or de- 

 stroying the inducing current. The last experiment consisted 

 in depressing the secondary coil to its original position \ the in- 

 tensity of the secondary currents produced by change of relative 



