COST OF ELECTRIC LIGHTING. 247 



burners, cocks, &c., for the 120 burners is ^60. Taking interest 

 at 5 per cent., to include wear and tear and renewals, there results 

 for i. ooo hours' consumption per annum 



J. d. 



Interest 900 



Cost of gas consumed .,. ... 135 o o 



,144 o o 



"At the utmost the 120 burners cannot give more than 2,400 

 candles' light, and naturally but a small percentage of this is 

 reached. Further, when steam or other vapour or fog arises the 

 gas-jets are obscured. The space being subdivided, it is neces- 

 sary to employ three machines. These three machines, with 

 lamps, conducting wires, mounting, &c., cost ^250.* 



" Thus the economy is 2 to i in favour of electric lighting. But 

 there is the further advantage that the lighting is perfect, and 

 that steam or vapour or fog does not cause inconvenience. If, 

 however, the ratio of light-intensities were adapted to the ratio 

 of efficiency, the advantage would be considerably higher (20 

 to i) in favour of electric lighting. It may be laid down, as 

 proved by experiment, that for lighting large spaces not too 

 much subdivided, the advantage is greatly in favour of the electric 

 light ; but that when numerous light-centres of sihall intensity are 

 required, or where the space is much subdivided, the advantage 

 is in favour of gas. This advantage will cease when a practical 

 method of subdividing the electric light has been obtained. In 

 places where opaque objects or screens occur that only throw- 

 shadow, but are not of sufficient size to completely block out the 

 light from the space they inclose, reflectors can be utilized to 

 overcome the difficulty of shadows. When the electric light is 

 capable of minute subdivision, it will undoubtedly compete with 

 gas on terms of the highest advantage, since the cost of establish- 

 ing a gasworks will be many times in excess of that necessary 

 to supply the electric light to a district. 



* Interest 15 per cent, upon ^'250 37 10 o 



Carbons, coals, attendance, oils, &c., per 1,000 hours 35 4 o 



72 14 o 



