J9 8 ELECTRIC LIGHTING. 



Petersburg, where three of these lamps are in operation, each 

 of them gives a light equal to 20 Carcel lamps, and they are 

 worked by the currents of one of the Alliance Company's 

 machines. 



Bouliguine's Lamp. This lamp accomplishes nearly 

 the same object as the preceding, but by using only one car- 

 bon. It is, like the former, composed of a copper base, two 

 vertical rods, two bars for conveying the current, and a valve 

 for exhausting. 



One of the rods is perforated by a small opening from top 

 to bottom, and nearly all its length there is a slit which 

 allows two small lateral projections to pass through. The 

 carbon is introduced into this rod as intoaporte-crayon, and 

 it tends to rise, by the action of counterpoises attached by 

 very small cords, to the lateral projectors on which the carbon 

 rests. The part of the carbon to be made incandescent is 

 held between the lips of two conical blocks of retort carbon. 

 A screw placed under the base enables the length of the rod 

 which carries the upper conical block to be increased or 

 diminished, and thus a greater or less length can be given to 

 the luminous part. The closing of the globe is accomplished, 

 as in the preceding apparatus, by the lateral pressure of 

 several caoutchouc discs. 



When the lamp is placed in a circuit, the carbon rod 

 glows and becomes luminous, until at length it breaks. At 

 this instant a little mechanism controlled by an electro- 

 magnet opens the lips of the carbon-holders : the counter- 

 poise of the upper one pushes out of the groove any frag- 

 ments which may remain, and the counterpoise of the lower 

 one raises the carbon rod, which goes into the upper block 

 and re-establishes the current. The mechanism controlled 

 by the electro-magnet again acts, but in the reverse direction 

 of its former movement, the porte-crayons are tightened, 

 and the light reappears. 



This system, according to Fontaine, does not always yield 



