PHOSPHORESCENCE. 53 



enable us to walk without hesitation in any open 

 country. 



Let the heavens be overcast, let the stars be 

 hidden by an unbroken mass of clouds, and still a 

 sufficiency of light will be diffused in the open 

 country to prevent the difficulty and inconve- 

 nience which would attend any attempt to walk 

 in a dark cave, or in an apartment the shutters 

 of which are closed. 



It appears to me that the atmosphere and the 

 clouds themselves act in these cases like the 

 phosplwri spoken of in a previous chapter. Being 

 exposed to the light of the sun the whole day 

 long, it is very probable that they emit a phos- 

 phorescent light like the Bologna stone, for in- 

 stance, when the Sun's rays are withdrawn from 

 them; and moreover, that this phosphorescence 

 may, in certain circumstances, assume an extra- 

 ordinary intensity, as we shall see by some of the 

 following examples. 



Here are the accounts by Eozier and Beccaria, 

 alluded to above : 



Eozier states that, being at Beziers, in France, 

 on the loth August, 1781, at a quarter before 

 eight in the evening, the sun having gone down 

 and the sky overcast, thunder was heard. At five 

 minutes past eight, the storm having attained its 

 height, Rozier observed a luminous point above 

 the brow of a hill fronting his house ; this point 



