Focus, and O the other Focus of the Metal, in which the Object is placed.
But to return from this digression, I told you, that Light is not similar, or homogeneal, but consists of difform Rays, some of which are more refrangible than others: So that of those, which are alike incident on the same Medium, some shall be more refracted than others, and that not by any virtue of the Glass, or other
external Cause, but from a predisposition, which every particular Ray hath to suffer a particular degree of Refraction.
I shall now proceed to acquaint you with another more notable deformity in its Rays, wherein the Origin of Colours is unfolded: Concerning which I shall lay down the Doctrine first, and then, for its Examination, give you an Instance or two of the Experiments, as a Specimen of the rest.
The Doctrine you will find comprehended and illustrated in the following Propositions.
- As the Rays of Light differ in degrees of Refrangibility, so they also