256 Intelligence and Miscellaneous Articles. 



If the duration of the communication, commencing with the 

 breaking of the current, exceeds a time which I have not tried to 

 estimate rigorously, but which is not much less than -001 of a 

 second, the condenser does not become charged, and the needle of 

 the electrometer remains at rest. 



If the duration of this communication is reduced to much less 

 than ?I ri"ffO" °^ a second, we find charges absolutely different ac- 

 cording to the instant at which this rapid contact is produced ; and 

 we can thus study, from less than -joihnF ^° ircnhrtf °^ a second, the 

 difference of potential presented by the extremities of the induced 

 ware. 



The following is then the succession of the phenomena which I 

 have observed : — 



Take the times for abscissas, the origin being at the metallic 

 rupture of the inducing current, and the differences of potential 

 (or, what comes to the same thing, the deflections of the needle) 

 for ordinates. 



At the time zero the difference of potential is nil ; it then in- 

 creases regularly, and at about yofony of a second reaches a maxi- 

 mum which can be kept to a remarkable degree constant ; it 

 afterwards decreases regularly, again becoming nil. But the phe- 

 nomenon does not end there. If the examination be continued, 

 the difference of potential changes sign, the positive extremity 

 becomes negative, and vice versa ; there is a new maximum reached 

 in the opposite direction, then a return to zero, then another 

 change of sign, &c. I have counted in this way as many as 30 

 oscillations. The first ocillations have always seemed to me longer 

 and more intense ; they appear to tend rapidly towards isochronism. 

 I beg, however, permission to reserve this question of the duration 

 of the oscillations, which a special commutator, I hope, will soon 

 enable me to determine. 



In regard to the intensities the results are very clear. I will 

 give an instance : — 



The inducing current being supplied by a single Daniell element 

 with water and sulphate of copper, the inducing bobbin having 

 only one thickness of wire, and the induced bobbin 10,000 turns of 

 wire J millim. in diameter, the first and second maxima reached a 

 difference of potential equivalent to 80 Daniell elements, betrayed 

 by a deflection of 350 divisions by the needle of the electrometer, 

 which I was obliged purposely to render less sensitive. The 20th 

 maximum reached 160 divisions. 



The oscillatory phenomenon was first described by M. Blaserna; 

 it was measured more carefully, but still only with respect to its 

 duration, by M. Bernstein, — both of these physicists sending the 

 induced current for only a very brief period into a galvanometer. 



I study the phenomenon in its entirety, from a purely static point 

 of view, without disturbing it ; and I get a constancy and intensity 

 of effect which permit me to trace, point by point, the curve which 

 represents it. — Comptes JRendus de VAcademie des Sciences, vol. 

 lxxxii. pp. 84-86. 



