64 ESSAYS AND OBSERVATIONS 



when the rays are more inclined to one 

 another, than when they are lefs fo ? For 

 the direction of the vibrations, raifed by 

 the adion of the hght, whether in the 

 colorific particles or thofe of an inferior 

 order, will more interfere with one another ; 

 from whence the inteftine (hocks and colli- 

 fions muft increafe : befides this, the colori- 

 fic particles of opaque bodies being dif- 

 pofed in various fituations, perhaps, upon 

 the whole, the rays will fall more direftly 

 on each, the more they are inclined to one 

 another. Is not this the reafon of what has 

 been remarked by philofophers*-:!-, That 

 the heat of the fun's light, colleded into a 

 cone, increafes in approaching the focus in a 

 much higher proportion than according to 

 its denfity ? That the difference of the 

 angle, in which the rays fall on any particle 

 of a given magnitude placed at different 

 diflances from the focus, is but fmall, is no 

 proof that the fhcemmenon cannot be afcribed 

 to it ; fince we know not in what high 

 proportion one or both the circumflances 

 now mentioned may operate. Howevery 



that 



* Boerhaave, Element, chemic. de igne. 

 f Muffchenbr, Elementa Phyfices, § 1040, 



