Description of a Carbon Voltaic Battery. 183 



zinc of the next pair, where it is soldered to the ear e, (fig. 1.) The 

 other ear of the same zinc is cut off below the surface of the bar, 

 and serves only to support the zinc firmly in its place. This ar- 

 rangement, it will be seen by inspecting the figure, brings out 

 the poles at the diagonally opposite corners, where a gallows 

 screw is fixed for attaching the series to the next group of 

 twelve. The twelve cups are confined in one position, by the 

 mahogany tray in, in which they are easily moved from place to 

 place. 



In the present battery there are eight groups of twelve pairs 

 each, or ninety-six pairs in all, exposing about one thousand two 

 hundred square inches of plumbago to three thousand of zinc. 

 The series may be connected with each other consecutively, and 

 used with the intensity of ninety-six pairs, and the quantity of 

 one member ; or they may, by the ingenious suggestion of Dr. 

 Hare in similar cases, be made to work with the intensity of 

 twelve pairs, and the accumulated quantity of eight groups, each 

 of twelve series. This beautiful mode of modifying the power 

 and action of a battery of a given number of plates, has been 

 described by Dr. Hare 3 in the Proceedings of the American Phi- 

 losophical Society for 1840.* 



The effects of this battery have given me much satisfaction. 

 In some respects I feel a good degree of assurance that it is supe- 

 rior to any other form of voltaic battery with which I am ac- 

 quainted. I regret that it is not in my power to compare it 

 more accurately with other batteries, and especially with Mr. 

 Grove's, as I have not now at my disposal a series on his construc- 

 tion. 



It is not supposed that the plumbago is quite equal to platina 

 for the negative element. Yet its surface is well calculated for 

 an electrode, and its conducting power is remarkable, when we 

 remember that it is not a metal, and indeed it seems to be but little 

 behind platina in this respect, especially as, from the size of the 

 mass employed, it may offer less resistance to the passage of an 

 electric current, than may be the case with a thin strip of platina. 



This is well worthy the name of a " constant battery," as its 

 action is continued for many hours, with apparently little decline. 

 The longest period in which I have employed one was eight 



* The same account may be found in Vol. xl, p, 49, of this Journal. 



