Mifcellanea Cur topi. 105 



external Caufe, but from a predifpofition, which 

 every particular Ray hath to fuffer a particular 

 degree of Refraction. 



I mall now proceed to acquaint you with ano- 

 ther more notable deformity in its Rays, wherein 

 the Origin of Colours is unfolded : Concerning 

 which I {hall lay down the DoUrine firft, and 

 then, for its Examination, give you an Inftance or 

 two of the Experiments , as a Specimen of the reft. 



The Doctrine you will find comprehended and 

 illuftrated in the following Propositions. 



1. As the Rays of Light differ in degrees of 

 Refrangibility, fb they aifb differ in their difc 

 pofition to exhibit this or that particular Co- 

 lour. Colours are not Qualifications of Light, 

 derived from Refractions, or Reflections of na- 

 tural Bodies, (a? 'tis generally believed) but Ori- 

 ginal and connate Properties, which in divers Rays 

 are divers. Some Rays are difpoled to exhibit a 

 red Colour and no other ; fbme a yellow and no 

 other, feme a green and no other, and fb of the 

 reft. Nor are there only Rays proper and par- 

 ticular to the more eminent Colours, but even to 

 all their intermediate Gradations. 



i. To the fame degree of Refrangibility ever 

 belongs the fame Colour, and to the fame Co- 

 lour ever belongs the fame degree of Refrangi- 

 bility. The leaft Refrangible Rays are all difpo- 

 fed to exhibit a Red Colour, and contrarily 

 thole Rays, which are difpofed to exhibit a Red 

 Colour, are all the leaft Refrangible ; So the 

 mofl Refrangible Rays are all diipofed to exhibit 

 a deep Violet Colour, and contrarily thofe which 

 are apt to exhibit fuch a Violet Colour, are all 

 themoft Refrangible. And fb to air the inter- 

 mediate Colours in a continued Series belong 

 intermediate degrees of Refrangibility. And 



this 



