PHYSICAL anp LITERARY 7 
rays will fall more diretly on each, the 
more they are inclined to one'another. Is 
not this the reafon of what has been re=_ 
marked by philofophers *+, That the 
heat of the fun’s light, colleéted into a 
cone, increafes in approaching the focus 
in a much higher proportion than accor- 
ding to its denfity ? That the. difference 
of the angle, in which the rays fallon any 
particle of a given magnitude placed at 
different diftances from the focus, is but 
fmall, is no proof that the phenomenon can= 
not be aferibed to it; fince we know not 
in what high.proportion one or both the 
eircumftances-now mentioned may ope- 
rate. However, that it proceeds not from 
any unknown a¢tion of the rays upon one 
-another, as has been infinuated t, is evi- 
dent from this, that each particular ray, 
after pafling through the focus, preferves 
its own colour and its own direction, in: 
the fame manner as if it were alone. 
QUER. 
_ * Boerhaave, Element. chemic. de igne, . 
t Mufichenbr, Elementa Phyfices, § 10402 
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