This, I conceive, is enough for an Introduction to Experiments of this kind; which if any of the Royal Society shall be so curious as to prosecute, I should be very glad to be informed with what success: That, if any thing seem to be defective, or to thwart this Relation, I may have an opportunity of giving farther Direction about it, or of acknowledging my Errors, if I have committed any.
Since the Publication of this Theory, some Misunderstandings happening between a French Philosopher at Paris and Mr. Newton, he has endeavour'd to explain himself a little further in these Things, according to the following Method.
A farther Explanation of the same Theory.
DEFINITIONS.
1. I call that Light Homogeneal, Similar, or Uniform, whose Rays are equally refrangible.
2. And that Heterogeneal, whose Rays are unequally refrangible.
Note, There are but three Affections of Light in which I have observ'd its Rays to differ; viz. Refrangibility, Reflexibility, and Colour; and those Rays which agree in Refrangibility, agree also in the other two, and therefore may well be defined Homogeneal; especially since Men usually call those things Homogeneal, which are so in all Qualities that come under their Knowledge, tho' in other Qualities, that their Knowledge extends not to, there may possibly be some Heterogeneity.
3. Those Colours I call Simple or Homogeneal, which are exhibited by Homogeneal Light.
4. And those Compound or Heterogeneal, which are exhibited by Heterogeneal Light.
5. Different Colours, I call, not only the more eminent Species, Red, Yellow, Green, Blue, Purple, but all other the minutest Gradations; much after the same manner, that not only the more eminent Degrees in Musick, but all the lead Gradations, are esteem'd different Sounds.