ELECTRIC CANDLES. 



219 



The manufacture of these candles, which is conducted on 

 the large scale* at No. 61 Avenue de Villiers, is very in- 

 teresting, especially the way in which the insulators are 

 made. A thin layer of sculptors' plaster mixed with sulphate 

 of barium, and so tempered as not to set quickly, is spread 

 upon a marble table slightly oiled, by means of a mould 

 made of a notched plate of zinc fitted into a sliding handle. 

 By drawing this mould along,- the plaster in front of it is 

 spread on the mar- 

 ble in the form of 

 grooves and projec- 

 tions to the length 

 of about 2 metres. 

 When the mould 

 has been passed 

 along several times, 

 a fresh quantity of 

 plaster is placed in 

 front of it, which 

 increases the thick- 

 ness of the projec- 

 tions, and after five 

 or six operations of 

 this kind these pro- 

 jections have exactly the thickness of the teeth of the mould 

 which is that suitable for the insulators. The sides of the 

 insulators are, of course, made slightly concave to receive 

 the cylindrical carbons. Their thickness is generally 3 milli- 

 metres between the carbons, and only 2 millimetres in the 

 other direction. 



Fig. 63 shows the way in which the Jablochkoff candles 

 are held in the lamp. There are places for four in the 

 figure, but the number may be larger; the lamps in the 

 Place de P Opera can hold twelve. Each support consists of 



FIG. 63. 



" : - Six or eight thousand are made per day. 



