VOLTAIC GENERATORS. 



at the expense of the tension effects, and for incandescence 

 calorific effects are especially necessary. 



Finally, if by reason of the resistance of the external circuit 

 or the condition of the ex- 

 periment, the electric cur- 

 rent must have both tension 

 and quantity, the cells are 

 arranged in series, that is 

 to say, in groups composed 

 of a greater or less number 

 of elements joined for quan- 

 tity, and these groups are 

 themselves joined for ten- 

 sion. 



By means, therefore, of 

 a battery of several cells or 

 elements, we may obtain 

 those various effects that 

 are peculiar to batteries of 

 a greater or less electro- 

 motive force ; but we must 

 remember that when several 

 cells are joined for quantity, 

 that is to say, by their like 

 poles, we do not thereby in- 

 crease the electro-motive fora 

 of the generator; this electro- 

 motive force always remains 

 the same as that of a single 

 cell, but the resistance is 

 diminished in proportion to 



the number of cells joined together, or, which comes to the 

 same thing, a cell of larger surface is formed. It must also 

 be borne in mind that the electro-motive force of a battery 

 does not depend on the size of its elements, but on the nature of 

 the physical and chemical actions that arise within it, and an 



