TRANSLA TOR'S APPENDICES. 3 T 7 



through them, but which may be safely carried as high as 20 

 candles. It is stated that i horse-power of force absorbed 

 suffices to maintain 10 of these lamps. At the Exhibition of 

 Electrical Apparatus at Paris in 1881, the Swan lamp re- 

 ceived the gold medal as being the best system in its class. 



Maxim's Lamp. The carbons for this lamp are prepared 

 from cartridge paper, and the vacuous bulbs contain a residual 

 atmosphere of a hydro-carbon instead of air. It is claimed 

 that by this the durability of the filament is increased, and 

 the irregularities of the resistance at various points become 

 equalized. This form of loop preferred by the inventor has 

 four parallel vertical portions, nearly like a capital M. The 

 resistance of this lamp is stated to be more than twice that 

 of Swan's lamp. The light given out maybe carried to 50 

 candles. 



Edison's Lamp and Fox-Lane's Lamp. Edison prepares 

 his carbon from a filament of bamboo, while Fox-Lane 

 makes use of a string of flax. Both make a single loop of 

 the carbon, which is bent into a horse-shoe form. The re- 

 sistance of Edison's lamp is about the same as that of Maxim's, 

 while the resistance of the Fox-Lane lamp is less than that 

 of the Swan. 



The Faure Secondary Battery. Plante's polarization 

 battery, which was invented about 1859, has been mentioned 

 in the text (page 15). This battery was formed by the action 

 of the current from a primary battery on plates of lead im- 

 mersed in diluted sulphuric acid. The nature of the polariz- 

 ing action itself is explained on page 9. Faure also uses 

 thin plates of lead for the elements of his cell, but instead of 

 forming lead oxide by electrolysis, he coats one of the plates 

 with a film of red oxide of lead, and this is separated from 

 the other plate by a layer of felt. The Faure cells, or 

 " accumulators," as they have been called, are made of a 

 large size, and according to Sir W. Thompson, one of these 

 cells, weighing 75 kilogrammes, "can store and give out 



