N_p_ which in the fourth Prism is more refracted, will become fuller and
stronger when the Light OP, which in the third Prism HJK is more
refracted, vanishes at P; and afterwards when the less refracted Light
OT vanishes at T, the less refracted Light N_t_ will become increased
whilst the more refracted Light at _p_ receives no farther increase. And
as the trajected beam MO in vanishing is always of such a Colour as
ought to result from the mixture of the Colours which fall upon the
Paper PT, so is the reflected beam MN always of such a Colour as ought
to result from the mixture of the Colours which fall upon the Paper
_pt_. For when the most refrangible Rays are by a total Reflexion taken
out of the beam MO, and leave that beam of an orange Colour, the Excess
of those Rays in the reflected Light, does not only make the violet,
indigo and blue at _p_ more full, but also makes the beam MN change from
the yellowish Colour of the Sun's Light, to a pale white inclining to
blue, and afterward recover its yellowish Colour again, so soon as all
the rest of the transmitted Light MOT is reflected.
Now seeing that in all this variety of Experiments, whether the Trial be
made in Light reflected, and that either from natural Bodies, as in the
first and second Experiment, or specular, as in the ninth; or in Light
refracted, and that either before the unequally refracted Rays are by
diverging separated from one another, and losing their whiteness which
they have altogether, appear severally of several Colours, as in the
fifth Experiment; or after they are separated from one another, and
appear colour'd as in the sixth, seventh, and eighth Experiments; or in
Light trajected through parallel Superficies, destroying each others
Effects, as in the tenth Experiment; there are always found Rays, which
at equal Incidences on the same Medium suffer unequal Refractions, and
that without any splitting or dilating of single Rays, or contingence in
the inequality of the Refractions, as is proved in the fifth and sixth
Experiments. And seeing the Rays which differ in Refrangibility may be
parted and sorted from one another, and that either by Refraction as in
the third Experiment, or by Reflexion as in the tenth, and then the
several sorts apart at equal Incidences suffer unequal Refractions, and
those sorts are more refracted than others after Separation, which were
more refracted before it, as in the sixth and following Experiments, and
if the Sun's Light be trajected through three or more cross Prisms
successively, those Rays which in the first Prism are refracted more
than others, are in all the following Prisms refracted more than others
in the same Rate and Proportion, as appears by the fifth Experiment;
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