e colours of the
Rain-bow, that is, there will be generated the two principal colours,
_Scarlet_ and _Blue_, and all the _intermediate_ ones which arise from the
composition and dilutings of these two, that is, cd shall exhibit a
_Scarlet_, which toward d is diluted into a _Yellow_; this is the
refraction of the Ray, ik, which comes from the underside of the Sun; and
the Ray ef shall appear of a deep _Blue_, which is gradually towards e
diluted into a pale _Watchet-blue_. Between d and e the two _diluted_
colours. _Blue_ and _Yellow_ are mixt and compounded into a _Green_; and
this I imagine to be the reason why _Green_ is so acceptable a colour to
the eye, and that either of the two extremes are, if intense, rather a
little offensive, namely, the being plac'd in the middle between the two
extremes, and compounded out of both those, _diluted_ also, or somewhat
qualifi'd, for the _composition_, arising from the mixture of the two
extremes _undiluted_, makes a _Purple_, which though it be a lovely colour,
and pretty acceptable to the eye, yet is it nothing comparable to the
ravishing pleasure with which a curious and well tempered _Green_ affects
the eye. If removing the Paper, the eye be plac'd against cd, it will
perceive the lower side of the Sun (or a Candle at night which is much
better, because it offends not the eye, and is more easily manageable) to
be of a deep _Red_, and if against ef it will perceive the upper part of
the luminous body to be of a deep _Blue_; and these colours will appear
deeper and deeper, according as the Rays from the luminous body fall more
_obliquely_ on the surface of the Water, and thereby suffer a greater
refraction, and the more distinct, the further cdef is removed from the
trajecting hole.

So that upon the whole, we shall find that the reason of the _Phaenomena_
seems to depend upon the _obliquity_ of the _orbicular pulse_, to the Lines
of Radiation, and in particular, that the Ray cd which constitutes the
_Scarlet_ has its inner parts, namely those which are next to the middle of
the luminous body, precedent to the outermost which are contiguous to the
dark and _unradiating_ skie. And that the Ray ef which gives a _Blue_, has
its outward part, namely, that which is contiguous to the dark side
precedent to the pulse from the innermost, which borders on the bright
_area_ of the luminous body.

We may observe further, that the cause of the _diluting_ of the colours
towards the middle