i988 ESSAYS ann OBSERVATIONS 
mift by going up fome neigbouring hill; 
then he will fometimes fee the whole coun- 
try around, as it were, buried under a vaft 
deluge; and nothing but the tops of diftant 
hills, appearing here and there above the 
flood; and he will think of diving down a- 
gain into it, with a kind of horror. The 
air at that time, in thefe regions, is very 
pure, ferene, and agreeable to breathe in. 
In this, or a fimilar fituation, there is a 
phenomenon obfervable, which I have feen 
many aa ago; namely, a rainbow formed 
round one’s fhadow in the mift. The French 
Gentlemen who went to Peru, with a view 
to determine the figure of the earth; having, 
among many other difficulties, the emba- 
rafiment of tedious and very frequent fogs to 
ftruggle with; had often occafion to ob- 
ferve this phenomenon. It feemed alfo worth 
mentioning here, that any one who has the 
curiofity may fatisfy himfelf concerning it. 
I HAD occafion to fee it again on the 23d 
of Oober laft, in: travelling from Glafgow, 
northward. When I had afcended a very 
little out of the fog, fo that my fhadow was 
projected amongtt it; the fun being behind, 
and almoft ona level with me; there was 2 
double 
