• PHYSICAL AND LITERARY, si 



fpace a 'particle- of light defcribes m 

 - . L,^ " . ■ ^ th Qf a fecond. With fo 



I i500OOOX>O0O000 



rapid a motion therefore may the inter- 

 nal part of bodies be agitated by the influence 

 of light, as to perform 125,000,000,000,000 

 vibrations or more in a fecond of time ! The 

 arrival of different particles of light at the 

 furface of the fame colorific particle in the 

 fame or different rays, may diflurb the regu- 

 larity of their vibrations, but will evidently 

 increafe their frequency, orraife ftili mi^ 

 nuter vibrations among the parts which "com- 

 pofe thefe particles ; by which means the 

 inteftine motion becomes more fubtile and 

 thoroughly diffufed. If the quantity of light 

 •admitted into the body be. increafed, the vi- 

 brations of the particles muff likeways in- 

 creafe in magnitude and velocity ; till, at laiR:, 

 they pay be fo violent as to make all the 

 component particles dafli one another to 

 pieces by their mutual collifions : in which 

 cafe, the colour and texture of the body muft 

 be deftroyed. Thus may we form, from 

 known principles, fome imperfed conce- 

 ption of the manner in which bodies are 

 heated and burned by the adion of light : 

 Mpre than an imperfedt notion of thefe fe- 



cret 



