These and the
like Examples, _Pyrophilus_, have induc'd me to Suspect, that the
Superficial Particles of White bodies, may for the Most part be as well
Convex as Smooth; I content my self to say _Suspect_ and _for the most
part_, because it seems not Easie to prove, that when Diaphanous bodies, as
we shall see by and by, are reduc'd into White Powders, each Corpuscle must
needs be of a Convex Superficies, since perhaps it may Suffice that
Specular Surfaces look severally ways. For (as we have seen) when a
Diaphanous Body comes to be reduc'd to very Minute parts, it thereby
requires a Multitude of Little Surfaces within a Narrow compass. And though
each of these should not be of a Figure Convenient to Reflect a Round Image
of the Sun, yet even from such an Inconveniently Figur'd body, there may be
Reflected some (either Streight or Crooked) Physical Line of Light, which
Line I call Physical, because it has some Breadth in it, and in which Line
in many cases some Refraction of the Light falling upon the Body it depends
on, may contribute to the Brightness, as if a Slender Wire, or Solid
Cylinder of Glass be expos'd to the Light, you shall see in some part of it
a vivid Line of Light, and if we were able to draw out and lay together a
Multitude of these Little Wires or Thrids of Glass, so Slender, that the
Eye could not discern a Distance betwixt the Luminous Lines, there is
little doubt (as far as I can guess by a Tryal purposely made with very
Slender, but far less Slender Thrids of Glass, whose Aggregate was Look'd
upon one way White) but the whole Physical Superficies compos'd of them,
would to the Eye appear White, and if so, it will not be always necessary
that the Figure of those Corpuscles, that make a Body appear White, should
be _Globulous_.
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