hose of natural Bodies, the distance is two Inches and three quarters.
And were the Colours still more full, I question not but that the
distance would be considerably greater. For the coloured Light of the
Prism, by the interfering of the Circles described in the second Figure
of the fifth Experiment, and also by the Light of the very bright Clouds
next the Sun's Body intermixing with these Colours, and by the Light
scattered by the Inequalities in the Polish of the Prism, was so very
much compounded, that the Species which those faint and dark Colours,
the indigo and violet, cast upon the Paper were not distinct enough to
be well observed.

_Exper._ 9. A Prism, whose two Angles at its Base were equal to one
another, and half right ones, and the third a right one, I placed in a
Beam of the Sun's Light let into a dark Chamber through a Hole in the
Window-shut, as in the third Experiment. And turning the Prism slowly
about its Axis, until all the Light which went through one of its
Angles, and was refracted by it began to be reflected by its Base, at
which till then it went out of the Glass, I observed that those Rays
which had suffered the greatest Refraction were sooner reflected than
the rest. I conceived therefore, that those Rays of the reflected Light,
which were most refrangible, did first of all by a total Reflexion
become more copious in that Light than the rest, and that afterwards the
rest also, by a total Reflexion, became as copious as these. To try
this, I made the reflected Light pass through another Prism, and being
refracted by it to fall afterwards upon a Sheet of white Paper placed
at some distance behind it, and there by that Refraction to paint the
usual Colours of the Prism. And then causing the first Prism to be
turned about its Axis as above, I observed that when those Rays, which
in this Prism had suffered the greatest Refraction, and appeared of a
blue and violet Colour began to be totally reflected, the blue and
violet Light on the Paper, which was most refracted in the second Prism,
received a sensible Increase above that of the red and yellow, which was
least refracted; and afterwards, when the rest of the Light which was
green, yellow, and red, began to be totally reflected in the first
Prism, the Light of those Colours on the Paper received as great an
Increase as the violet and blue had done before. Whence 'tis manifest,
that the Beam of Light reflected by the Base of the Prism, being
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