THE ELECTRIC LIGHT. 437 



through all the others, and add its electro-motive force 

 to that of all the others. We increase, it is true, at the 

 same time the resistance of the battery, diminishing 

 thereby the quantity of the current from each cell, but 

 we augment the power of the integrated current to 

 overcome external hindrances. The resistance of the 

 battery itself may, indeed, be rendered so great, that 

 the external resistance shall vanish in comparison. 

 What is here said regarding the voltaic battery is 

 equally true of magneto-electric machines. If we wish 

 our current to leap over five intervals, and produce five 

 lights in succession, we must invoke a sufficient electro- 

 motive force. This is done through multiplying, by 

 the use of thin wires, the convolutions of the rotating 

 armature as, a moment ago, we augmented the cells of 

 our voltaic battery. Each additional convolution, like 

 each additional cell, adds its electro-motive force to that 

 of all the others; and though it also adds its resistance, 

 thereby diminishing the quantity of current contrib- 

 uted by each convolution, the integrated current be- 

 comes endowed with the power of leaping across the 

 successive spaces necessary for the production of a series 

 of lights in its course. The current is, as it were, ren- 

 dered at once thinner and more piercing by the simul- 

 taneous addition of internal resistance and electro-mo- 

 tive power. The machines, on the other hand, which 

 produce only a single light have a small internal resist- 

 ance associated with a small electro-motive force. In 

 such machines the wire of the rotating armature is com- 

 paratively short and thick, copper riband instead of wire 

 being commonly employed. Such machines deliver a 

 large quantity of electricity of low tension in other 

 words, of low leaping power. Hence, though competent 

 when their power is converged upon a single interval, to 

 produce one splendid light, their currents are unable to 



