of the Light emitted by Luminous Bodies. 35 



once found that my Argand's lamp, when it was burn- 

 ing with its greatest brilliancy, gave twelve times as 

 much light as a good wax candle f of an inch in diam- 

 eter, but never more. 



Of the Fluctuations of the Light emitted by Candles. 



To determine to what the ordinary variations in the 

 quantity of light emitted by a common wax candle 

 might amount, I took such a candle, and lighting it 

 placed it before the photometer, and over against it an 

 Argand's lamp, which was burning with a very steady 

 flame ; and measuring the intensity of the light emitted 

 by the candle from time to time, during an hour, the 

 candle being occasionally snuffed when it appeared to 

 stand in need of it, its light was found to vary from 

 100 to about 60. The light of a wax candle of an 

 inferior quality was still more unequal, but even this 

 was but trifling compared to the inequalities of the 

 light of a tallow candle. 



An ordinary tallow candle, of rather an inferior 

 quality, having been just snuffed and burning with 

 its greatest brilliancy, its light was as 100; in eleven 

 minutes it was but 39 ; after eight 'minutes more had 

 elapsed, its light was reduced to 23; and in ten min- 

 utes more, or twenty-nine minutes after it had been 

 last snuffed, its light was reduced to 16. Upon being 

 again snuffed, it recovered its original brilliancy, 100. 



Of the relative Quantities of Beeswax, Tallow, Olive 

 Oil, Rape Oil, and Linseed Oil, consumed in the 

 Production of Light. 



In order to ascertain the relative quantities of bees- 

 wax and of olive oil consumed in the production of 



