1 70 ELECTRIC LIGHTING. 



may also be advantageously applied to all the regulators 

 which automatically separate the carbons, and it renders 

 their action more certain and regular, whatever may be the 

 variations in the intensity of the current. This system has 

 been successfully applied to the Serrin regulators, used at 

 the Chemin defer de r Quest (St. Lazare station). 



De Mersaime's Lamp. De Mersanne's regulator was 

 invented to enable straight carbons to supply an electric 

 light for at least sixteen hours consecutively. 



The system, represented in Fig. 42, is essentially formed of 

 two slide boxes B B', fixed on a strong upright stand of cast 

 iron. Through these slide the two cylindrical carbons c and 

 c', each 75 centimetres or more in length, moved by a re- 

 gulated action. In order that the carbons may be adjusted 

 to have their points in the same vertical line, the boxes are 

 capable of turning a little vertically, and the upper one can 

 also be turned horizontally. The sliding system of both 

 boxes consists of four grooved rollers, two of which are con- 

 nected with the two ends of a lever, and are pressed against 

 the carbons by a spiral spring v. These rollers serve as 

 guides, and the other two, of larger diameter and with a 

 roughened surface, act as the movers of the carbons. For 

 this purpose these are set in motion by wheels fixed on an 

 axle, connected by mitre wheels with a vertical shaft A A. 

 This shaft, being capable of turning in either direction, ac- 

 cording to the action of the regulating apparatus, can make 

 the carbons approach to, or recede from, each other. The 

 carbons are supported and protected outside of the boxes 

 by enclosing tubes. 



The regulating apparatus is placed in a case below the 

 slide box B' of the lower carbon. It consists in the first 

 place of clockwork driven by a spring barrel,* and by an. 

 electro-magnet E forming part of a derived circuit from the 



* This barrel, when wound up, will act for 36 hours without attention, 



