204 ELECTRIC LIGHTING. 



the lateral contact has a less complicated arrangement, and 

 the weight P which acts on the movable carbon to produce 

 the end contact, is placed above the upper end of the carbon. 

 It may therefore be selected as required. The end contact 

 itself is fixed instead of turning round. The arrangement 

 given to the apparatus enables it to be suspended from a 

 ceiling. It can also be placed horizontally : in that case a 

 spring propels the movable carbon. 



Experiments made at Sautter and Lemonnier's, with ten 

 Reynier lamps and a Gramme machine with a speed of 930 

 turns, gave the following results in a circuit represented by 

 100 metres of copper wire of 3 millemetres, or 30 metres of 

 telegraph wire : 



Serrin's regulator gave under the same circumstances, with 

 a deviation of 21, a luminous intensity of 320 jets. 



As regards total luminous intensity, the use of incandescence 

 lamps is therefore less advantageous than that of arc lamps; but 

 with the former there is the advantage of the division of the 

 light, and the possibility of obtaining it with comparatively 

 small electrical power. They consume about 10 centimetres 

 of carbon per hour; but by taking larger carbons and arrang 

 ing the generators for quantity, this consumption may be 

 much reduced. In the experiments made at the Societc 

 d* encouragement, six lamps could be lighted with the current 

 from 25 double Bunsen cells. Their light through ground 

 glass globes was soft, and appeared about equal to that of 

 two or three gas-jets. They could be lighted and extin- 

 guished at will. 



In the year 1876, S. A. Varley had patented a lamp on a 

 similar plan which we show in Fig. 55, and which is de- 

 scribed as follows : 



