Disjunction-currents between Poles of different shapes. 27 



of intensity of the spark undergoes a change in form, although 

 both induction-currents pass with equal facility. That this 

 cannot be the case can be easily seen from the following con- 

 siderations. 



We assume for a moment that both induction- currents tra- 

 verse the spark in exactly equal proportions; the electricities 

 which have passed are then exactly equal, whether the induction- 

 coil is in the circuit or not ; and therefore it is solely the change in 

 the curve of intensity of the spark when the induction-coil is in- 

 serted between e and g or between e and k which causes the 

 diminution in the deflection of the disjunction-current. But it 

 is to be remarked that the intensity of the spark increases when 

 the induction-coil is inserted between e and k, while it decreases 

 when the coil is between e and g ; two entirely opposite changes 

 in the intensity would thus both have the same effect — that is, a di- 

 minution in the deflection produced by the disjunction-current. 

 This would only be possible if the deflection which the disjunction- 

 current produces when there is no induction were really a maxi- 

 mum, so that a change in the shape of the spark in either direction 

 could not increase the deflection. But that this deflection is not a 

 maximum follows from the fact that the introduction of the in- 

 duction-coil in all cases diminishes the deflection, whether there 

 is a greater or a smaller distance between the knobs, or whether 

 there is or is not a bridge in front of the galvanometer, whether 

 the condensers have greater or smaller coatings, or whatever 

 be the other circumstances on which the form of the curve of 

 intensity of the spark depends. Hence it follows that the 

 two induction-currents cannot traverse the spark in equal pro- 

 portion. 



But, instead of this, we might say that it is not those induc- 

 tion-currents which traverse the spark in the same direction as 

 the charge which pass most easily and in greatest proportion, 

 but this is the case with the currents which go in the opposite 

 direction to the discharge, and therefore in the same direction as 

 the disjunction-currents. The latter, it is true, are added to 

 the disjunction-current and thereby increase the deflection ; but, 

 on the other hand, they produce so great a diminution in the dis- 

 integration of the poles, that, on the whole, the deflection is 

 thereby diminished. Many proofs may be adduced for the ab- 

 surdity of this opinion; but the question is most easily settled 

 by the following experiments. 



We assume for the moment that that induction-current which 

 is in the opposite direction to the discharge, or in the same direc- 

 tion as the disjunction-current, most readily penetrates the spark, 

 and, in the manner just described, effects the diminution observed 

 in the deflection. To acquire a better idea of this matter, we 



