36 Experiments on the Relative Intensities 



light, I proceeded in the following manner. Having 

 provided an end of a wax candle of the best quality, 

 .68 of an inch in diameter, and about 4 inches in 

 length, and a lamp with five small wicks, which I had 

 found upon trial to give the same quantity of light as 

 the candle, I weighed very exactly the candle and the 

 lamp filled with oil, and then placing them at equal 

 distances (40 inches) before the field of the photom- 

 eter I lighted them both at the same time ; and after 

 having caused them to burn with precisely the same 

 degree of brightness just one complete hour, I extin- 

 guished them both, and weighing them a second time 

 I found that 100 parts of wax and 129 parts of oil had 

 been consumed. 



Hence it appears that the consumption of beeswax 

 is to the consumption of olive oil in the production of 

 the same given quantity of light as 100 is to 129. 



In this experiment no circumstance was neglected 

 that could tend to render the result of it conclusive. 

 Care was taken to snuff the candle very often with a 

 pair of sharp scissors, in order to make it burn con- 

 stantly with the same degree of brilliancy; and the 

 light of the lamp was, during the whole time, kept in 

 the most exact equilibrium with the light of the candle, 

 which was easily done by occasionally drawing out a 

 little more or less one or more of its five equal wicks. 

 These wicks, which were placed in a right line perpen- 

 dicular to a line drawn from the middle wick to the 

 middle of the field of the photometer, were about tV of 

 an inch in diameter each, and \ of an inch from each 

 other, and when they were lighted their flames united 

 into one broad, thin, and very clear white flame, with- 

 out the least appearance of smoke. 



