mes from the red half, and by consequence is more refrangible.

_Illustration._ In the eleventh Figure, MN represents the Window, and DE
the Paper terminated with parallel Sides DJ and HE, and by the
transverse Line FG distinguished into two halfs, the one DG of an
intensely blue Colour, the other FE of an intensely red. And BAC_cab_
represents the Prism whose refracting Planes AB_ba_ and AC_ca_ meet in
the Edge of the refracting Angle A_a_. This Edge A_a_ being upward, is
parallel both to the Horizon, and to the Parallel-Edges of the Paper DJ
and HE, and the transverse Line FG is perpendicular to the Plane of the
Window. And _de_ represents the Image of the Paper seen by Refraction
upwards in such manner, that the blue half DG is carried higher to _dg_
than the red half FE is to _fe_, and therefore suffers a greater
Refraction. If the Edge of the refracting Angle be turned downward, the
Image of the Paper will be refracted downward; suppose to [Greek: de],
and the blue half will be refracted lower to [Greek: dg] than the red
half is to [Greek: pe].

[Illustration: FIG. 11.]

_Exper._ 2. About the aforesaid Paper, whose two halfs were painted over
with red and blue, and which was stiff like thin Pasteboard, I lapped
several times a slender Thred of very black Silk, in such manner that
the several parts of the Thred might appear upon the Colours like so
many black Lines drawn over them, or like long and slender dark Shadows
cast upon them. I might have drawn black Lines with a Pen, but the
Threds were smaller and better defined. This Paper thus coloured and
lined I set against a Wall perpendicularly to the Horizon, so that one
of the Colours might stand to the Right Hand, and the other to the Left.
Close before the Paper, at the Confine of the Colours below, I placed a
Candle to illuminate the Paper strongly: For the Experiment was tried in
the Night. The Flame of the Candle reached up to the lower edge of the
Paper, or a very little higher. Then at the distance of six Feet, and
one or two Inches from the Paper upon the Floor I erected a Glass Lens
four Inches and a quarter broad, which might collect the Rays coming
from the several Points of the Paper, and make them converge towards so
many other Points at the same distance of six Feet, and one or two
Inches on the other side of the Lens, and so form the Image of the
coloured Paper upon a white Paper placed there, after the same manner
that a Lens at a Hole in a Windo