244 ELECTRIC LIGHTING. 



"These figures are deduced from practice, and we have never 

 found that they are too favourable : on the contrary, it has ia 

 many cases been observed that the cost per Carcel lamp is less 

 than that we have named." 



According to the tables given in Fontaine's work, pages 

 200 and 201, it appears that for the same luminous intensity,, 

 the Gramme machine, under the most unfavourable circum- 

 stances, would produce a light 



75 times cheaper than that of wax candles. 

 55 stearine candles. 



16 colza oil. 



ii gas at 30 centimes per cu DIG metre. 



6| ., gas at 15 centimes per cubic metre. 



Under the most favourable conditions this light would be 



300 times cheaper than that of wax candles. 

 200 stearine candles. 



' 65 colza oil. 



40 gas at 30 centimes per cubic metre. 



22 gas at 1 5 centimes per cubic metre. 



The economy in the cost of lighting by fitting up a 

 spinning-mill of 800 looms with Gramme machines, instead 

 of fitting it up with gas, is found to be 33 percent, and this 

 with six times as much light supplied. 



From an interesting notice just published by R. V. Picon, 

 engineer of arts and manufactures, we extract the following 

 particulars, which appear free from all exaggeration in either 

 direction, and which indicate the price of a franc as repre- 

 senting the expense of an electric lamp per hour. 



According to Picon, an electric lamp supplied by an ordi- 

 nary Gramme machine would be able to illuminate from 

 250 to 500 square metres of a workshop in which minute 

 operations are carried on; 500 to 1,000 square metres of 

 machine-fitting shops, and 2,000 square metres of a work 

 yard. 



The expense of fitting-up would be 



