VOLTAIC ARC 



LAMPS. 



pulleys over which 

 passed the cords 

 that moved the 

 carbons an un- 

 equal diameter 

 proportional to the 

 amount of the con- 

 sumption. Nor 

 does he describe 

 the way in which 

 the detent acted; 

 but it seems from 

 his description that 

 it was merely by a 

 simpte pressure 

 against a drum 

 fixed on the axle 

 of the two pulleys, 

 on which were 

 wound in opposite 

 directions the 

 cords attached to 

 the carbon -hold- 

 ers. 



Be that as it 

 may, this appara- 

 tus has been the 

 starting point for 

 all those we are 

 about to mention, 

 and which require 

 a definite place for 

 each pole of the 

 battery. 



Some years after 

 the apparatus just 



