Disk 



Disk 



Disk 



ositive. 



negative. 



positive 



19-6 



30'8 



22-8 



32 On 'Electrical Induction- and Disjunction-currents. 



Experiment 29, — 



Mean deflections ♦ 



Experiment 30. — 



Mean deflections . . 12*3 19*2 12*2 



We can hereby explain the peculiarity that, in that position 

 of the valve which gives the smallest deflection in a space filled 

 with air, the deflection remains unaltered towards the same side 

 when the air in the valve is rarefied. 



On a superficial consideration, it may seem absurd to sup- 

 pose that the disjunction-current can produce upon the magnetic 

 needle an action many times as powerful as the discharge by which 

 it is caused. It might be thought that the direct action of the 

 discharge upon the magnetic needle must be just as great as when 

 this current first produces a disjunction-current which subse- 

 quently exerts magnetic action. Yet it may easily be seen that 

 this discrepancy is only apparent. That electricity consists of 

 motion is indubitable ; but this presupposes something which 

 moves, whether it is the smallest particles of a body, the 

 aether, or any other body. Now, if the mass set in motion in 

 the electrical discharge be called M, and its velocity V, MV 2 

 is its vis viva in the discharge. If, in like manner, m denotes 

 the mass in motion in the disjunction-current, and v its velo- 

 city, mv 2 is the vis viva of the disjunction-current. This latter 

 quantity cannot be greater than the former, but smaller ; for the 

 entire vis viva of the discharge never passes to the disjunction- 

 current. If, now, the deflection of the magnetic needle were pro- 

 portional to the vis viva of the current which acts upon it, the de- 

 flection which the disjunction-current causes could not possibly 

 be greater than that which the discharge could directly produce ; 

 but the action upon the magnetic needle is not proportional to 

 the vis viva, but to the intensity ; that is, proportional to mv ; 

 and this quantity may readily be many times as great as MV, 

 although mv 2 must always be less than, or at most equal to MV 2 . 

 If, for instance, M=l and V = 100, MV 2 = 10000; if j» = 10000 

 and v=xl, MV 2 = mv 2 , but mv = 100MV. In the electrical dis- 

 charge the mass moved is inconsiderable, but its velocity is 

 large; in the disjunction-current the reverse is the case. By 

 the mechanical work which the discharge performs in the spark, 

 one of these forms of motion is changed into the other. 



I will remark, in conclusion, that in my opinion it would be 

 desirable to revise the electrical investigations which were insti- 

 tuted before the discovery of the electrical disjunction- current, 

 and in which electrical sparks and an enclosed circuit occurred. 

 However trustworthy the observations, the explanations could 

 scarcely be either correct or complete when this mode of de- 

 velopment of electricity was unknown. 



