Light and the volume of Gas consumed. 28 
can only be conjectured, but assuming that the observation 
made the uncorrected rendering 11:32 candles (a very probable 
quantity) we find that the law of the squares of consumption 
then makes the ratio as follows :— 
46" 2 1 YS2a05* 14, 
a result which in view of the facts before given cannot be 
regarded as accidental. The theorem applied to this case as it 
stands reported (including the correction) gives for the value 
of the fourth term of the ratio 14°7 candles. 
I have endeavored to apply this theorem to some of the re- 
sults recorded in the well known researches of Messrs. Audouin 
and Bérard, but I find these results stated in a manner 
which renders it difficult to fix clearly the terms of compari- 
son. I venture, however, to append a few comparisons drawn 
from two of the tabular records of experiments with butterfly 
or bat’s wing burners of the “fifth series” which so far as 
they go lend confirmation to the views here presented. 
Burner of the fifth series—slit J inch wide. 
,_|Consumption of the comparative |Intensities by 
Consumption ofthe} Bengel Argand P 
Burners under standard intensities. law of ee Pressures. 
trial. —_|_bumer without | yumner=f00. jeonsumption. | 
Cubic feet. Cubic feet. 
3°1079 3°6024 50 103 *23622 
2°4015 3°5318 40 90°9 *19685 
2°0131 3°6024 S 96° "11811 
Burners of same series—slit 353 inch wide. 
3°9555 3°6730 80 92°6 078474 
3°1786 3°6730 60 80°7 07480 
2°6487 3°6730 50 96°7 "07480 : 
2°3309 3°6730 40 97°5 03937 
15186 3°6730 20 115°6 01968 ) 
rd- 
ant, to be considered as otherwise than pointing clearly to its 
general truth. A rigorous demonstration cannot be expected, 
as there are too many variable functions of unknown value in- 
volved in the best methods at present known for photometric 
