1 66 ELECTRIC LIGHTING. 



lever L. Finally, a screw K, which passes through the case 

 of the lamp, allows the distance of the armature to be pro- 

 perly adjusted to the current employed, and a small addition 

 N, which also projects from the case, shows whether the 

 electro-magnetic system is properly vibrating. The wire of 

 the electro-magnet E is moreover connected with the mass of 

 the apparatus, in order that the current which passes through 

 and illuminates the carbons may be derived through the 

 circuit-breaker at each attractive movement of the armature, 

 and produce the vibration of the lever L by closing a short 

 circuit. 



The action of this apparatus is very simple. When a current 

 passes through the electro-magnet E, the catch Q is withdrawn 

 from the wheel i, and the upper carbon-holder, by weighing 

 on the wheels of the clockwork, sets them going until the 

 carbons guided by racks engaging these wheels are brought 

 into contact. But if under these conditions the generator is 

 put into communication with the lamp by the binding screws 

 z and c, the current traverses the electro-magnet E, the mass 

 of the apparatus, the upper carbon-holder, the lower carbon- 

 holder, and returns to the generator by the communication 

 connecting this with the binding screw z; the carbons then 

 glow at their point of contact, the electro-magnet becomes 

 active, and the catch Q, by acting on the ratchet wheel I, 

 causes it to advance one tooth, by which the carbons are 

 separated. But in this movement a contact is set up at x 

 between the lever and the screw c, and the current, finding 

 less resistance in passing by that path than through the 

 electro-magnet E, in a great measure leaves the latter ; then 

 the armature, being no longer sufficiently attracted, causes a 

 backward movement of the lever L, which again withdraws 

 the catch Q, destroys the contact at x, and brings about a 

 new attraction of the armature involving a new movement of 

 the wheel i; and as these alternating motions are more 

 rapidly effected than that which results from the setting in 

 motion of the wheels by the action of the upper carbon-holder's 



