34 Experiments on the Relative Intensities 



Now as the quantity of light produced by the 

 Argand's lamp in this experiment is to the quantity 

 produced by the common lamp as 17956 to 9063, or 

 as 187 to 100, while the quantity of oil consumed by 

 the former is to that consumed by the latter only in 

 the ratio of 253 to 163, or as 155 to 100, it is evident 

 that the quantity of light produced by the combustion 

 of a given quantity of oil in an Argand's lamp is 

 greater than that produced by burning the same quan- 

 tity in a common lamp, in the ratio of 187 to 155, or 

 as 100 to 85. 



The saving, therefore, of oil which arises from 

 making use of an Argand's lamp, instead of a common 

 lamp, in the production of light, is evident; and it 

 appears from this experiment that that saving cannot 

 amount to less than 1 5 per cent. How far the advan- 

 tage of this saving may, under certain circumstances, 

 be counterbalanced by inconveniences that may attend 

 the making use of this improved lamp, I will not pre- 

 tend to determine. 



Of the relative Quantities of Light e^nitted by an 

 Argand's Lamp and by a common Wax Caridle. 



I have made a considerable number of experiments 

 to determine this point, and the general result of them 

 is that a common Argand's lamp, burning with its 

 usual brightness, gives about as much light as nine 

 good wax candles ; but the sizes and qualities of can- 

 dles are so various, and the light produced by the 

 same candle so fluctuating, that it is very difficult to 

 ascertain with any kind of precision what a common 

 wax candle is, or how much light it ought to give. I 



