VOLTAIC ARC LAMPS. I7 



and thence a continuous light by their superposition on the 

 organ of sight. In order to avoid a continuance of the action 

 on the carbon-holders when the carbons are consumed, the 

 upper carbon-holder has a head, which by meeting a circuit- 

 breaker stops the current through the apparatus. Under 

 these conditions, the spark of the extra current of the electro- 

 magnetic system is joined to that of the generator, and 

 increases its brilliancy. 



Houston and Thomson do not, of course, announce this 

 regulator as suitable for feeble currents and lights. Maiche 

 sought the same object, and Lemolt also used this means to 

 produce a voltaic arc with powerful generators, only it was a 

 clockwork mechanism which gave the vibrating movements 

 to the carbons. 



Hlolera and Cebriaii's Lamp. This system of lamp 

 was invented for distributing the light in several directions 

 by optical means. The apparatus consists, therefore, of a 

 regulator, with the luminous point enclosed in a polyhedric 

 cage, with faces provided with Fresnel's lenses. With this 

 object, the two carbons are supported by two systems of 

 regulating carbon-holders entering at a certain angle within 

 the cage, and directed towards its centre. These carbon- 

 holders are fitted to the two ends of a tube filled with a 

 liquid, in which they form a kind of pistons which may be 

 pushed to a greater or less distance according to the pres- 

 sure exercised by the liquid in the tube. At one part of this 

 tube there is a kind of bellows, the movable part of which is 

 provided with a plate of iron, which serves as the armature 

 of an electro-magnet placed in the arc circuit. This arma- 

 ture being more or less energetically attracted, according to 

 the greater or less intensity of the light current, exercises a 

 greater or less pressure which causes the carbons to advance 

 proportionally to their consumption, and therefore maintains 

 them in the centre of the cage. This pressure may, how- 

 ever, be regulated by means of an antagonistic screw. When 



