1150 The Galvanic Battery. [No. 108. 



Having long been impressed with a sense of the great economical 

 importance of the Battery in all the varied operations in which the 

 explosive force of gunpowder is employed, and having had an ex- 

 cellent opportunity of becoming acquainted with its details during 

 the progress of the demolition of the barque "Equitable," in which 

 I had the pleasure of being employed under Capt. Fitzgerald, I was 

 led to prepare this paper, in the hope of rendering the experience 

 then attained, available to the fullest extent for the benefit of 

 others under similar circumstances. After a considerable portion 

 of it had been written, I learned that a pamphlet by Col. Pasley 

 on the same subject was in course of publication, and I therefore im- 

 mediately laid my paper aside. On receiving Col. Pasley's pamphlet, 

 however, I found it was entirely confined to details of his own plans, 

 and as experience had proved that these admitted of most material im- 

 provements and modifications, I conceived my paper might still be 

 useful, and accordingly resumed and completed it. The original plan 

 has been extended by the addition of a section " on the Theory of 

 the Battery," in which the recently published views of Sir Michael 

 Faraday on this long disputed point, have been briefly developed ; and as 

 his researches have entirely removed it from the domain of " doubtful 

 knowledge," as he himself terms it, to that of inductive certainty, the 

 addition may prove interesting to those who desire to understand the 

 principles as well as the practical applications of the Galvanic Battery. 



Section I. — The Construction of the Galvanic Battery. 



The elementary form of the Galvanic Battery consists simply in the 

 interposition, between two plates of different metals, (usually copper 

 and zinc) of a fluid capable of exerting some action on one of these 

 plates, while it has none, or at least a different one, on the other. A 

 communication established between the plates, either by direct contact, 

 or by the interposition of some conducting substance, then admits of 

 the circulation of a current of Galvanic electricity. 



It would be foreign to the design of this paper, to dwell upon the 

 various combinations and modifications of the above elementary Battery, 

 by which different compound circles have been formed ; and information 

 concerning these is the less called for, since all have been recently 



