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An for iAoaßcur N. his Expression, Thut I mnintnin my DoElrine vrith ferne<:oncem, 1 confess it was a littlc Ungrateh.il to me, to meet with Objectionswhich had been anlwered besore, without liaving the least reason given me whyVid. fup. f. thole Anfwers were insufficient. Thole Anfwers were to shew, that therei4p. &i«q. are ot ] ier (imple Colours belides Bine and Yellow; 1 instanced in a Simple orHomogeneal Grecn,- such as cannot be made by mixing Blue and Yellow orany other Colours. And I allö fhew’d why, liippoimg that all Coloursmight be produeed out of two, yet ic would not follow that thole two arethe only Original Colours. The Reaföns I delire you would compare withwhat bath been now lind of White. And so the necelsity of all Colours toproduce White, might have appeared by that Experiment, where I lay, Thatif any Colour at the Lcns be interceptcd, the Whitenels (which is Com-pounded of thein all/ will be changed into (the resolt of/ the other Colours.

Howcver, since there leems to have happen’d sorne misonderstanding be-tween us, I (hall endeuvour to expla-in my lelf a little further in thele tliings,according to the following Method.

Desinit ions!] i. I call that Light Homogeneal, Similar, or Uniform, whofeRays are equaliy Refrangible.

a. And that Heterogeneal, whofe Rays are unequally Refrangible.

Note. There are but thrte Aftections of Light, in which I have oblcrvedits Rays to difier, vhp licfrnngibiiity , Ifeflexibility, and Colour ; andthole Rays which agree in Refrangibiiity agree also in the other two,and therefore may well be delined Homogeneal dpccially since Älen uso-ally call thofe things Homogeneal, which are so in all Qualities .thatcome under their Knowledge, tho’ in other Qualities, that their Know-ledge extends not to, there may polsibly be sorne Heterogeneity.

Z •" Thole Colours I call Simple, or Homogeneal, which are exhibited byHomogeneal Light.

4. And thole Compound or Heterogeneal, which are exhibited by Heteroge-neal Light.

5. Difterent Colours I call not only the more eminent Species, Red, Yel-low, Green, Blue, Purple, but all other the minutest Gradations; much as-ter the läme mariner that not only the more Eminent Degrees in Mustek,but all the leaff Gradations are esteetned different Sounds.

Propositione .(] 1. The Sun’s Light consists of Rays differing by indefinite de-grees of Refrangibiiity.

2. Rays which diiler in Refrangibiiity when parted From one another, doproportionally difier in the Colours which they exhibit. These two Propositi-oris are matter of fast.

z There areas many Simple or Homogeneal Colours asdegrees of Refran-gibiiity. For to every degree of Refrangibiiity belongs a different Colour,;hy P'rop. 1. and that Colour is Simple, by Des .1, and z.

4. Whitenels