24 ELECTRIC LIGHTING, 



times been proposed, and among others the use of fluorescent 

 globes, capable of absorbing these chemical rays ; but this 

 improvement was obtained at the expense of the illuminating 

 power, thus making the advantages of the electric light less 

 marked. 



In comparing different luminous sources with each other, 

 Foucault and Fizeau have found that the light of the ordinary 

 voltaic arc is one-half less than that of the sun, whilst the 

 Drummond light (oxy-hydrogen) is only the one hundred 

 and fiftieth part. Now the sun throws upon a given surface 

 as much light as 5,774 candles placed at 0-33 metre from 

 that surface. 



