needful to preferve the material Syfient . 213 
the blue cloud ?. And would not this appearance indicate, that 
the blye-rays of their light were tran{mitted, and the other 
coloured rays, for the moft part, refleéted from the atmofphere ? ? 
Would not that tranfiniffion of the blue rays occafion all bodies 
around us to appear blue, fo long as the atmofphere, continuing 
clear, íhould exhibit the blue cloud ? And would not the co- 
lours of thofe bodies vary as other coloured clouds fhould fuc- 
ceed and predominate ? - 
Would not this reflection of the other coloured rays occafion, - 
not only a decreafe of light, but, with refpe& to the fun, a 
great diminution of its heat ?: If the feveral different coloured 
rays do each, in refpe& to heat, produce an equal effe& ; and ` 
all but the blue.rays are reflected, fhould we not, in a clear day, - 
-be deprived of fix fevenths, or'a proportionable part, of the 
fun’ s heat, BRES the feven forts of rays, had they been all tranf- - 
carances and effects might have been expected. if the © 
aligned ut -Droduced the phenomenon : for the fun's light 
and other light; and alfo bodies in general, whatever be their 
colour, being viewed through.a medium of any original ‘colour, » 
will appear-of that. colour, or ftrongly tinged with it. - But it 
is apprehended, that no fuch appearances and effects have ever 
been obíerved ; and, therefore, that there is reafon to doubt 
the reality of the caufe afügned : the infufficiency of which 
may further appear in the courfe of thefe obfervations. 
But how is the exiftence of the orb deduced from the phe- 
nomenon ?—In the fame manner as the exiftence of the other 
heavenly bodies, and the exiftence of the bodies around us are 
deduced.: namely, from the uniformity and permanency of their ` 
vifible qualities, or phenomena. A 
