40 ESSAYS anp OBSERVATIONS 
of the earth? For it-is well known, that 
a fluid heated by its conta& with a folid 
body decreafes in heat, in fome inver{e 
proportion to the diftance from the body. 
But, to have this queftion fully determi- 
ned, the temperature of the air in the val+ 
Jey and on the mountain top muft be ob- 
ferved every hour both night and day, 
and carefully compared together. | 
~ Quer. V. From what has been laid 
down in Se&, 2. concerning the manner 
of the action of light in heating bodies, 
is it not reafonable to fuppofe that the 
heat produced by a given number of rays, 
in an opaque body of a given magnitude, 
muft be greater when the rays are more 
inclined to one another, than when they 
are lefs fo? For the dire@tion of the vi- 
brations, raifed by the action of the light, 
whether in the colorific particles or thofe 
of an inferior order, will more interfere 
with one another; from whence the inte- 
ftine fhocks'and collifions muft increafe: 
Befides thisy'the colorific particles of o- 
paque bodies being difpofed in various 
fituations, perhaps, upon the whole, the 
Taya 
