184 ELECTRIC LIGHTING. . 



and adjusting screws enable the luminous beam to be turned 

 in any required direction. 



With carbons 20 inches long and 5 millimetres in diameter, 

 the light supplied by the lamp lasts, according to Rapieff, 

 for seven or eight hours ; but with a diameter of 6 millimetres 

 these carbons may last two hours longer. This light may be 

 reckoned at IOD or 120 gas-jets, or at 1,000 candles; but 

 with Rapieff's smaller patterns one may be obtained not ex- 

 ceeding 5 gas-jets. The inventor has also constructed 

 patterns in which the preceding arrangement is reversed, in 

 order that they may be hung from the ceiling. According 

 to him, the resistance of the arc does not exceed 3 ohms, or 

 300 metres. 



In another arrangement Rapieff combines the action of 

 the voltaic arc with the luminous effect of a piece of kaolin 

 placed above the arc. The four carbons are then arranged 

 so as to form the four edges of a pyramid broken off at its 

 summit, where a kind of bell of kaolin is placed, like the 

 extinguisher of a lamp, and this when glowing increases the 

 illuminating power, according to Rapieff, by 40 per cent. 

 The carbons are Carre's, and a Gramme machine is the 

 generator. With this machine 10 lamps of the first described 

 pattern may be lighted by placing them in the same circuit, 

 but only 6 are used in the Times office at London, where 

 this mode of lighting has been in use for some time. 



According to the Telegraphic Journal of the ist Novem- 

 ber, 1878, Rapieff's system of electric lighting, introduced 

 into England by E. J. Reed, under the direction of Apple- 

 garth, has given excellent results in the trials which have 

 been made at Smithfield and at the establishment of the 

 London Times. The compositors' room is now lighted by 

 1 8 Rapieff lamps, and 6 are appropriated to lighting the 

 offices. "The great advantage of this lamp," he says, "is 

 that it will go a whole night without a renewal of the car- 

 bons ; its intensity is always constant, even when the carbons 

 are burned very low, and in this respect the lamp is prefer- 



