Dana on Electrical Battery. 293 



comparatively small, the instrument occupies a large space, 

 and it cannot be readily removed from place to place without 

 much trouble and risk ; the apparatus is, moreover, very ex- 

 pensive, and when one of the jars is broken, another of the 

 same dimensions cannot readily be found to supply its place. 



It occurred to me, that a Battery might be constructed of 

 plates of glass and sheets of tinfoil, in which the same extent 

 of coated surface should occupy a much smaller space, and 

 consequently that the apparatus would be more convenient 

 and more portable. I selected several panes of glass, the 

 surfaces of which coincided closely with each other, and then 

 arranged them with sheets of tinfoil in this order, viz. pane 

 of glass, sheet of tinfoil, then another pane of glass, then a 

 second sheet of tinfoil, and so on ; the sheets of foil being 

 smaller than the plates of glass by two inches all around ; the 

 glass being 10 by 12, and the foil 6 by 8. This apparatus 

 contained six plates of tinfoil, and the lowest plate being num- 

 bered one, was connected with the ground, and by slips of tin- 

 foil passing over the edges, with the third plate, and this, in 

 like manner with the Jifth. The second plate was connected 

 with the fourth, and this with the sixth, which communicated 

 with the conductor of the machine ; in this manner each plate 

 positively electritied will be opposed by one negatively electri- 

 fied, and vice versa ; the 6th, 4th, and 2d plates positive, and 

 the 5th, 3d, and 1st, negative. Into this apparatus I could in- 

 troduce a powerful charge, but not possessing a battery of the 

 common form, could not make comparative experiments. The 

 annexed figures will explain the construction of this apparatus. 



(See Plate.) 



Fig. 1. a 1, a 2, &c. the tinfoil. Fig. 2. a, the intermediate slips pass- 



b b b, plates of glass. ing over the edges of the 



c, the intermediate slips con- glass and connecting plates, 

 necting the plates 6, 4, 1,3, and 5. 



and 2. b, the slip which connects the 



d, the slips connecting 5, 3, 1, upper sheet offoil with the 4th, 

 and the ground. &c. 



In a battery of the ordinary form, it is evident that a much 

 less surface is coated than ia one of the above constructioD ; 



