The Light which comes through drops of Rain by two Refractions without
any Reflexion, ought to appear strongest at the distance of about 26
Degrees from the Sun, and to decay gradually both ways as the distance
from him increases and decreases. And the same is to be understood of
Light transmitted through spherical Hail-stones. And if the Hail be a
little flatted, as it often is, the Light transmitted may grow so strong
at a little less distance than that of 26 Degrees, as to form a Halo
about the Sun or Moon; which Halo, as often as the Hail-stones are duly
figured may be colour'd, and then it must be red within by the least
refrangible Rays, and blue without by the most refrangible ones,
especially if the Hail-stones have opake Globules of Snow in their
center to intercept the Light within the Halo (as _Hugenius_ has
observ'd) and make the inside thereof more distinctly defined than it
would otherwise be. For such Hail-stones, though spherical, by
terminating the Light by the Snow, may make a Halo red within and
colourless without, and darker in the red than without, as Halos used to
be. For of those Rays which pass close by the Snow the Rubriform will be
least refracted, and so come to the Eye in the directest Lines.
The Light which passes through a drop of Rain after two Refractions, and
three or more Reflexions, is scarce strong enough to cause a sensible
Bow; but in those Cylinders of Ice by which _Hugenius_ explains the
_Parhelia_, it may perhaps be sensible.
_PROP._ X. PROB. V.
_By the discovered Properties of Light to explain the permanent Colours
of Natural Bodies._
These Colours arise from hence, that some natural Bodies reflect some
sorts of Rays, others other sorts more copiously than the rest. Minium
reflects the least refrangible or red-making Rays most copiously, and
thence appears red. Violets reflect the most refrangible most copiously,
and thence have their Colour, and so of other Bodies. Every Body
reflects the Rays of its own Colour more copiously than the rest, and
from their excess and predominance in the reflected Light has its
Colour.
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