breaking a Circuit between the Poles of a Magnet. 463 



Primary broken 

 outside. 



Primary broken 

 inside. 



21 

 20-5 

 22 

 20 



27 



28 

 28 

 27 



Mean 20-0 



275 



When no condenser was used the deflections were as follows: — 



Primary broken 

 outside. 



Primary broken 

 inside. 



20 

 19 



20 

 20 



22-5 

 23-5 

 23-5 

 24 



19-75 



23-4 



The electromotive force in the circuit was very small, hardly- 

 enough to render the poles strongly magnetic. With a proper 

 electromotive force we might expect the effects to be more 

 striking. 



In order to measure the increase of quantity obtained by 

 breaking the primary circuit between the poles of the magnet, 

 the electromagnet and the primary of an induction-coil were 

 placed in the same circuit as at first. The poles of the induc- 

 tion-coil were connected (the one directly, the other by means 

 of the spark leaping between two points) with a condenser of -^ 

 farad capacity. The poles of the condenser were connected 

 with a Thomson's galvanometer of 5880 ohms resistance. 

 Each of the following results is the mean of two observations. 

 The length of spark was the same in both cases. 





Primary broken 

 outside. 



Primary broken 

 inside. 



6 cells. 

 4 „ 



17 5 



12 



2105 

 17 



The resistance of the six cells (Bunsen) was greater than the 

 resistance of the primary circuit. 



On another day the same arrangement gave the following 

 result, where each is a mean of two observations : — 



