Intelligence and Miscellaneous Articles. 



319 



merit they become the seat of induction, we explain effects which 

 are otherwise inexplicable, and show how dynamic electricity may 

 be changed into electricity of tension. — Comptes Rendus, June 22, 

 1868. 



THIRD NOTE ON THE LAWS OF INDUCTION. 

 BY MM. JAMIN AND ROGER. 



If n' batteries, of the force A and the resistance r, are united in 

 tension, they constitute a single one having the force n'A and the 

 resistance n'r ; and, finally, if n of these mixed batteries were joined 

 in parallel order, they would constitute a single one the constants of 



The heat reproduced in the external 



which would be n'A and 

 circuit x will be 



C = 



» f2 A a a? 



/n'r . \ 



We have connected our plates in couples of two, or in groups of 

 three, or we have joined them all in tension ; the results of ex- 

 periment have confirmed the formula, as is proved by the following 

 Table :— 



Plates grouped. 



Resist- 

 ances. 



One couple. 



Two couples. 



Three couples. 



Two groups of 

 three. 



Six plates in 

 tension. 



Thermal units. 



Thermal units. 



Thermal units. 



Thermal units. 



Thermal units. 



Obs. 



Calc. 



Obs. 



Calc. 



Obs. 



Calc. 



Obs. 



Calc. 



Obs. 



Calc. 



58 



225 



2-44 



6-80 



6-67 



10-52 



10-93 



7-27 



805 







92 



292 



3-06 



7-97 



7-32 



10-99 



10-93 



912 



9-51 







144 



3-35 



3-51 



7-43 



725 



9-80 



9-99 



11-05 



1098 







173 



3-98 



364 



7-05 



6-99 



9-22 



9-24 



1093 



11 08 







239 



3-86 



3-69 



627 



6-37 



7-90 



7-97 



10-35 



10-88 







303 



3-63 



3-60 



6-30 



5-76 



7-19 



6-96 



8-93 



9-51 







452 



3-38 



3-25 



4-59 



4-65 



5-26, 



5-33 



7-40 



8-63 







612 



2-86 



286 



3-87 



3-81 



4-25 



4-23 



7-02 



7-32 



11-32 



11 08 



Our experiments may be thus generalized : — 



Whenever bobbins in any number pass with a constant velocity at 

 the same distances in front of magnets, they act like the elements of 

 a constant battery. Notwithstanding interruptions or inversions of 

 the current, the quantity of electricity produced is governed by Ohm's 

 law, and the heat regenerated in the external circuit by that of Joule. 

 These laws apply to all modes of grouping bobbins. The electro- 

 motive force of each bobbin varies with the velocity, and with all 

 the circumstances of the construction. 



The same is the case with the resistance p of this couple ; it is 

 always greater than the resistance of the wires composing the bobbin. 



a and p had still to be measured — that is, compared with the con- 

 stants of a known element. For this purpose we measured with 

 twenty Bunsen's elements the heat produced in the external circuit r ; 



