232 



ELECTRIC LIGHTING. 



part of the current passing below it, that it will tend to move 

 towards the fixed conductor, and consequently will be kept 

 at the end of the carbons. Jamin thus describes his inven- 

 tion in a note laid before the Academic des Sciences on the 

 28th April, 1879: 



" I have the honour of present- 

 ing to the Academic a model of 

 an electric burner reduced to the 

 greatest possible simplicity. The 

 two carbons are kept parallel by 

 two insulated copper tubes, sepa- 

 rated by a space of 2 or 3 milli- 

 metres ; they slide with friction in 

 these tubes, which serve at once 

 to keep the carbons in their 

 places and to convey the current 

 to them. The carbons are sur- 

 rounded by a circuit of five or six 

 spires wound on a slender rec- 

 tangular frame 40 centimetres 

 long and 15 wide. I have ex- 

 plained how this circuit, traversed 

 by the same current as the car- 

 bons and in the same direction, 

 brings the arc to the end of the 

 carbon points and keeps it there. 

 " The lighting is done auto- 

 matically. For this purpose the 

 two ends of the carbons are sur- 

 rounded by a thin India-rubber 

 band, which presses them to- 

 gether ; then a little higher a small 



fragment of iron wire is placed between them, which puts them 

 into close communication at a single point. As soon as the cir- 

 cuit is closed, the current passes through this wire, heats it to 

 redness, and melts the India-rubber; the two carbons being 

 liberated now separate, and the arc is established with a kind of 

 explosion. Carbons of any thickness up to 8 millimetres may 

 be used. With this size the consumption scarcely exceeds 8 



FIG. 67. 



