Considerations of Mr. Hook upon Mr. Newton's Discourse of Light and Colours

```                                not insuperable. I have made many tryals, both for Telescopes and
Microscopes by Reflection, which I have mentioned in my Micrographia
but deserted it as to Telescopes, when I considered, that the focus of
the spherical concave is not a point but a Line, and that the Rayss are
lesse true reflected to a point by a concave, than refracted by
a Convex; which made me seek that by Refraction which J found
could not rationally be expected by Reflection; nor indeed could
I find any effect of it by one of six foot Radius, which about 7 or 8
years since M<sup>r</sup>. Reive made for M<sup>r</sup>. Gregory, whith which I made
several tryals; but it now appears it was for want of a good
Encheiria (from which cause many good Experiments have
been lost) both which considerations discouraged me from attempting
further that way; especially, since I found the Parabola much more
difficult to describe, than the Hyperbola or Elipses. And I was
wholly taken from the thoughts of it, by lighting on divers ways
which in Theory answered all I could wish for, though having
much more businesse I could not attend to bring them into use
for Telescopes; though for Microscopes I have for a good while
used it. Thus much as to the Preamble, I shall now consider the
Propositions themselves.

First then, M<sup>r</sup>. Newton alledgeth, that as the Rayss of Light differ
in Refrangibility, so they differ in their disposition to exhibit this
or that colour. With which I do in the main agree, that is, that
the Ray by refraction is, as twere split or rarified, and that the
one side, namely that which is most refracted, gives a <u>Blew</u>, and
that which is least, a <u>Red</u>; the intermediate are the dilutings
and intermixtures of those two, which I thus explain: The motion
of Light in an uniforme medium, in which it is generated, is pro=
pagated by simple and uniforme pulses or waves, which are at right
Angles with the line of direction; but falling obliquely on the
Refracting medium, it receives another impression or motion, which
disturbs the former motion, somewhat like the Vibration of a string and
```
images

Manuscript details

Author
Robert Hooke
Reference
RBO/4/45
Series
RBO
Date
1672
IIIF
(What's this?)
This is a link to the IIIF web URL for this item. You can drag and drop the IIIF image link into other compatible viewers

Cite as

Considerations of Mr. Hook upon Mr. Newton's Discourse of Light and Colours, 1672. From The Royal Society, RBO/4/45