98 WRITINGS OF JOSEPH HENRY. [1835 



iment, a phenomenon was observed in reference to the action 

 of the battery itself, which I do not recollect to have seen 

 mentioned, although it is intimately connected with the facts 

 of Magneto-electricity, as well as with the subject of these 

 investigations, viz.: When the body is made to form a part 

 of a galvanic circuit composed of a number of elements, a 

 shock is of course felt at the moment of completing the cir- 

 cuit. If the battery be not very large, little or no effect will 

 be perceived during the uninterrupted circulation of the gal- 

 vanic current; but if the circuit be interrupted by breaking 

 the contact at any point, a shock will be felt at the moment, 

 nearly as intense as that given when the contact was first 

 formed. The secondary shock is rendered more evident, 

 when the batter,y is in feeble action, by placing in the mouth 

 the end of one of the wires connected with the poles; a shock 

 and flash of light will be perceived when the circuit is com- 

 pleted, and also the same when the contact is broken at any 

 point, but nothing of the kind will be perceived in the inter- 

 mediate time, although the circuit may continue uninter- 

 rupted for some minutes. This I consider an important fact 

 in reference to the action of the voltaic current. 



The phenomena described in this paper appear to be in- 

 timately connected with those of Magneto-electricity, and 

 this opinion I advanced with the announcement of the first 

 fact of these researches in the American Journal of Science. 

 They may I conceive be all referred to that species of dynam- 

 ical Induction discovered by Mr. Faraday, which produces 

 the following phenomenon, namely: when two wires, A and 

 B, are placed side by side, but not in contact, and a voltaic 

 current is passed through A, there is a current produced in 

 B, but in an opposite direction. The current in B exists 

 only for an instant, although the current in A may be in- 

 definitely continued; but if the current in A be stopped, 

 there is produced in B a second current, in an opposite direc- 

 tion however to the first current. 



The above fundamental fact in Magneto-electricity appears 

 to me to be a direct consequence of the statical principles of 

 ** Electrical Induction^^ as mathematically investigated by 



