82 ESSAYS anp OBSERVATIONS 
through the atmofphere whofe parts are 
not big enough to give them the appear- 
ance of vifible opaque clouds? Do not . 
thofe who fay *, that the ethereal blue 
proceeds from the mixture of the fun’s 
white light reflected faintly by the atmo- 
{phere with the perfeét blacknefs of the’: 
celeftial fpace behind, revive, without a- 
ny neceflity, the antient confufed notion, 
that all colours may be formed by cer- 
tain compofitions of light and fhade? Als 
though the atmofphere reflects more blue — 
rays than what go to the formation of 
perfect white, it is eafy to conceive how 
coloured bodies, illuminated by it, may 
not be fenfibly tin@ured with blue. Let 
us fuppofe, that the atmofphere reflects 
+ more of blue rays than of the other co- 
lours, and that vermilion refle@s +2 of 
the red rays incident upon it, and 3; of 
every other colour; then, it is clear, that 
the 1ed rays, reflected by. the vermilion, 
will {till exceed the blue reflected by it, 
as 19 exceeds 1 +7:So that the purity of 
its’ 
* Nature difplayed, vol, 4. And Mufchen, Phyf. §. 1403-: 
