VOLTAIC ARC LAMPS. 



17* 



two carbons, as in Lontin's system ; and in the second place, 

 of another electro-magnet M interposed in the same deriva- 

 tion, and acting on the box B' 

 of the lower carbon in such a 

 manner as to separate the car- 

 bons when they come into con- 

 tact. When the apparatus is 

 not in action, the carbons are 

 generally separated by a greater 

 or less interval; but as soon 

 as the circuit is closed through 

 the apparatus, the two electro- 

 magnets are excited, for the 

 current then wholly passes 

 through the derivation, and the 

 clockwork is liberated, while 

 the lower holder is so inclined 

 as exactly to bring the two 

 carbons one over the other. 

 The advance of the carbons 

 takes place slowly, and when 

 they 'come into contact, the 

 current, finding a more direct 

 path, abandons the derivation 

 and the electro-magnets, and 

 passes almost entirely through 

 the circuit of the carbons, 

 which then glow, and imme- 

 diately supply the voltaic arc. 

 The electro-magnet M having 

 become inactive, the box B' 

 of the lower carbon-holder is 

 slightly inclined forward, and 

 by this causes not only the 

 disjunction of the carbons, but also a sufficient separation of 

 their points in consequence of the action produced on the 



FIG. 42. 



