1 62 ELECTRIC LIGHTING. 



mechanisms, in direct communication with the electro-rnag- 

 netic system, forms an oscillating system, composed of a kind 

 of double jointed parallelogram, to which are attached the 

 tube and accessories belonging to the lower carbon. It is 

 formed of four parallel horizontal arms, turning on the tube 

 of the upper carbon-holder and connected together by two 

 vertical cross pieces. 



The other mechanism, which we shall call the advancing 

 mechanism, is connected with the carbon -holders, and is 

 formed of wheelwork, together with a rack and draw chain. 

 The first mechanism, while acting, as we shall see, directly 

 on the lower carbon-holder, controls the action of the second 

 mechanism ; and this last, by rendering regular the ap- 

 proach of the carbons towards each other, carries out the 

 mechanical effect begun by the first. With this object, the 

 tube belonging to the lower carbon and forming part of the 

 oscillating system, carries a stop of triangular shape which 

 acts on the wings of a fly, forming the last moving piece of the 

 advancing mechanism. The oscillating system connected 

 by the two vertical cross pieces carries a cylindrical arma- 

 ture, which being placed within the influence of an electro- 

 magnet acting tangentially on it, can more or less lower it 

 according to the intensity of the current traversing the 

 system. There are two opposing springs fixed to the lower 

 arms of the oscillating system, and these springs are attached 

 to the supports of the wheels, and raise the system when the 

 current does not act with energy sufficient to counteract their 

 effect. It follows therefore from this arrangement that, with 

 an adequate electrical intensity, the oscillating system is suffi- 

 ciently lowered to arrest the advancing system, and with an 

 inadequate intensity this last system, being set at liberty, 

 allows the carbons to approach each other merely by the 

 effect of gravity on the upper carbon-holder, which is heavy 

 enough to produce the movement of the system. Let us now 

 see how the advancing system is arranged. 



In the first place, it is formed of a set of four wheels, the 



