INCANDESCENT LAMPS. 



207 



carbon has been advantageously replaced by a disc of 

 copper. 



Experiments made in 

 England with a Gramme 

 machine arranged for 

 electroplating and work- 

 ed by a steam engine of 

 (it is stated) two horse- 

 power, * gave, according 

 to Werdermann, the fol- 

 lowing results : 



" i. When the current 

 of the machine was distri- 

 buted between two lamps, 

 the brightness of the light 

 was equal to that of 360 

 candles. This light was 

 white, and apparently free 

 from the blue and red ray 

 so often perceived in the 

 light of the voltaic arc. 

 It was, besides, perfectly 

 steady. 



"2. By placing in the 

 circuit 10 derivations, each 

 corresponding with one 

 lamp, as shown in Fig. 

 57, 10 luminous centres 

 could be obtained, each 

 representing about 40 can- 

 dles. In order to render 

 the action steady, coils 

 a a a of small resistance 

 are interposed in each de- 

 rivation. Under these conditions the resistance of each lamp 

 was 0-392 ohm, and therefore the total resistance of the circuit 

 was only 0x337 ohm. 



* According to the particulars sent to me, this power should be greater. 



