Management of Light in Illumination. 195 



By the lamp No. I 137 parts. 



By the lamp No. 2 203 „ 



By the lamp No. 3 228 „ 



Wax consumed by the standard wax candle in 

 furnishing constantly the same quantity of 



light during the same time 100 „ 



When these lamps were made to furnish 200° of 

 light during one hour, the quantities of oil consumed 

 by them were as follows : — 



By the lamp No. I i6o parts. 



By the lamp No. 2 226 „ 



By the lamp No. 3 271 „ 



Quantity of wax necessary in order to furnish the 

 same quantity of light during the same time 



by means of two wax candles 200 „ 



When 300° of light were furnished by each of these 

 lamps during one hour, the quantities of oil consumed 

 were found to be as follows : — 



By the lamp No. i 2or parts. 



By the lamp No. 2 286 „ 



By the lamp No. 3 305 „ 



Quantity of wax necessary to produce the same 

 quantity of light during the same time by 



means of three wax candles 300 ,, 



From these results it is perfectly evident that, where 

 a small quantity of light is wanted, small lamps are 

 much more economical than large ones, when both are 

 constructed on the same principles. When Argand 

 burners are used, the cause of this difference may 

 easily be perceived and perfectly understood. A cir- 

 cular flame, which is at the same time low and wide, is 

 much more exposed to being rapidly cooled by the air 

 and by other surrounding cold bodies than a hollow 

 flame, which is narrower and higher. 



As the lamp No. i could not be made to furnish 

 constantly for any considerable time much more than 



