COST OF ELECTRIC LIGHTING. 245 



Gramme machine 1,500 fr. 



Serrin lamp 4 



Accessories of the above ... 5 



Conducting wires 5 



Transmission :> 



Carriage and packing .-. 5 



Various IOQ 



Total ... 2,300 

 and the working expenses per hour would be : 



Fr. c. 



Retort carbon ... ' 21 



Coke for motive power o' 1 5 



Working expenses and management ... o'io 

 Sinking of 2,300 fr., divided over 500 hours 



of lighting yearly 0-49 



Total 0-92 



If lighted throughout every night, that is to say, 4,000 

 hours in a year, the cost falls to 53 centimes. 



With an hydraulic motor the expenses are 77 centimes for 

 an illumination of 500 hour?, and 38 centimes for an illumi- 

 nation of 4,000 hours. 



A workshop of 60 metres by 20 will require two lamps, 

 which will entail a cost of i fr. 77 c. per hour instead of 

 3fr. 50 c., the expense of 100 gas-lights that would have to 

 l>e used in such a case, and which would give only one-fifth 

 or one-sixth of the total intensity of light. 



If the workshop is open all the night, the cost per hour 

 becomes o fr. 97 c. with the electric light, and 3fr. 07 c. for the 

 gas. 



It will be interesting to compare these indications with the 

 results that were published in England after the Trinity House 

 experiments, and we give an abstract of these from a paper 

 xead before the Society of Civil Engineers of London, by 

 Higgs and Brittle, entitled " On some recent Improvements in 

 Dynamo-electric Apparatus. " 



