GALVANISM. 



made to succeed one another in the same 

 regular order throughout the series. 

 The efficacy of this combination realized 

 the most sanguine anticipations of the 

 discoverer : it far exceeded in power the 

 single circle already described. If the 

 uppermost disc of metal in the column 

 be touched with the finger of one hand, 

 previously wetted, while a finger of the 

 other hand is applied to the lowermost 

 disc, a distinct shock is felt in the arms, 

 similar to that from a Leyden phial, or 

 still more nearly resembling that from 

 an electrical battery weakly charged. 

 A repetition of shocks is obtained for an 

 indefinite period, whenever the circuit is 

 completed by touching the two ends of 

 the pile with the moistened fingers. The 

 strength of the shock is, as might be 

 expected, greater in proportion to the 

 number of plates of which the pile is 

 composed. 



If the pile were raised to any consi- 

 5 derable height, it would 



obviously be in danger 

 of oversetting : this 

 may be prevented by 

 placing the discs be- 

 tween three vertical 

 glass rods, properly var- 

 nished, and cemented 

 into two thick pieces of 

 wood, one of which 

 serves as a base, and 

 the other as a cover to 

 the pile. See fig. 5. 



(11.) Any number 

 of these piles may be 

 combined so as to form a battery, 

 by making a metallic communication 

 between the last plate of the one and 

 the first of the next, and so on ; taking 

 care that the order of succession of the 

 plates in the circuit be preserved invio- 

 late, as is shown in fig. 6, where the dark 



Fig. 6. 



may be arranged in a form somewhat 

 different from the preceding, and corre- 

 sponding more nearly to the elementary 

 galvanic circle in its simplest state al- 

 ready described ($ 4, 5). In this new ar- 

 rangement the metallic plates, instead of 

 being piled one above the other, are 

 placed side by side in a vertical position, 

 and combined together in pairs, consist- 

 ing each of one zinc and one copper (or 

 silver) plate, connected at their upper 

 edges by slips of metal, passing from 

 the one to the other. A sufficient num- 

 ber of glasses being provided, and filled 

 with water, or some acid or saline solu- 

 tion, they are to be placed side by side, 

 so as to form a circle. The two plates 

 belonging to each pair are then to be 

 immersed in the fluids contained in two 

 different, but adjoining, glasses ; the 

 zinc plate, for instance, in the first glass, 

 and the copper in the second. The 

 plates of the second pair must be im- 

 mersed, in a similar way, in the second 

 and third glasses ; and so on successively 

 throughout the series, taking care to 

 preserve the same order of alternation in 

 the metals. It is evident that by this 

 arrangement, (of which an horizontal 

 section is shown infg. 7, where the dark 



Fig. 7. 



lines represent the copper, and the light 

 lines the zinc plates. 

 (12.) The component parts of the pile 



lines indicate the copper, and the lighter 

 lines the zinc plates in each pair,) each 

 vessel will contain one plate of zinc and 

 one of copper, which, as they belong to 

 different pairs, are not connected toge- 

 ther, except through the medium of the 

 intervening fluid in that particular 

 vessel. 



(13.) The first apparatus of this kind 

 was constructed by Volta, who employed 

 for that purpose a circular series of 

 cups, and hence gave it the name of 



