40 . Experiments on the Relative hitensities 



that the light of the flame affects the eye in such a 

 manner as to render it insensible to the weaker light 

 emitted by or reflected from the objects placed behind 

 it, I conceived that a very strong light would not only be 

 visible through a weak flame, but also (as all transpar- 

 ent bodies are invisible) that it might perhaps cause 

 the flame totally to disappear. To determine that fact, 

 I took a lighted candle, at mid-day, the sun shining 

 moderately bright, and holding it up between my eye 

 and the sun I found the flame of the candle to disap- 

 pear entirely. It was not even necessary, in order to 

 cause the flame to become invisible, to bring it to be 

 directly between the eye and the body of the sun : it 

 was sufficient for that purpose to bring it into the 

 neighbourhood of the sun where the light was very 

 strong ; even in a situation in which the light was not 

 so strong as to dazzle the eye so much as to prevent 

 its seeing very distinctly the body of the candle and 

 the wick, not the least appearance of flame was discern- 

 ible, though the candle actually burned the whole time 

 very vigorously. 



