THE ELECTRIC TELEGEAPH. 



36. ONE of the most simple forms of voltaic battery is that 

 represented in fig. 6, which consists of a glazed earthen- 



ware trough, divided by 



partitions into a series of 



/ + 4- *> 'g"~^_ * x- * ^fr parallel cells, and a series of 



of shape and magnitude cor- 

 responding with the cells, 

 attached to a wooden rod, 



each c PP er P late bein s 



connected at the top, under 

 the wood, by a band of 

 metal, with the zinc plate 

 which immediately succeeds 

 it in the series. For brevity, let us designate the first copper plate, 

 C 1} the second C 2 , the third, C 3 , and so on, proceeding from A' 

 towards B', and let the first zinc plate, which is connected with c x 

 by a metal band, be called z 2 , the next, which is similarly connected 

 with C 2 , be called z 3 , and so on from A' towards B'. Now, the 

 intervals between the plates being so arranged as to correspond 

 with the width of the cells, the series of plates may be let down 

 into the cells so that a partition shall separate every pair of plates 

 which are connected by a metal band. Thus, the first partition 

 will pass between c x and z 2 , the second between C 2 and z 3 ,|the third 

 between C 3 and Z 4 , and so on. It appears, therefore, that the first 

 cell proceeding from A towards B will contain only the copper plate 

 c x , the second will contain c 2 and Z 2 , the third, C 3 and z 3 , and so 

 on, the last cell at the extremity B of the series containing only 

 the last zinc plate, which we shall call z n . 



Now, it is evident that as the arrangement thus stands, the first 

 and last cells of the series would differ from the intermediate ones, 

 inasmuch as, while each of the latter contains a pair of plates, 

 each of the former contains only a single plate, the first copper 

 c t and the last zinc z n . To complete the arrangement, therefore, 

 it will be necessary to place a zinc plate, which we shall call z x , in 

 the first cell to the left of C 1? and so as not to be in contact with it, 

 and in like manner a copper plate, which we shall call c n , in the 

 last cell B to the right of z n , and so as not to be in contact with it. 

 Let wires be soldered to the upper edges of these terminal plates 

 Zj and c n , and let them be carried to any desired distances, but 

 finally connected with plates, or any other masses of metal, buried 

 in the ground at n' and j 1 /, fig. 7. 



These dispositions being made, let us suppose the cells to be 

 filled with a weak acid solution, such as has been already described, 

 but so that the liquid in one cell may not overflow into the next. 

 130 



