14. And perhaps, (_Pyrophilus_) it may prove some _Illustration of what I
mean_, and help you to conceive how _this may_ be, if I Represent, that
where the Particles are so exceeding Slender, we may allow the Parts
expos'd to the Sight and Touch to be a little Convex in comparison of the
Erected Particle of Black Bodies, as if there were Wyres I know not how
many times Slenderer than a Hair: whether you suppose them to be Figur'd
like Needles, or Cylindrically, like the Hairs of a Brush, with
Hemisphærical (or at least Convex) Tops, they will be so very Slender, and
consequently the Points both of the one sort and the other so very Sharp,
that even an exquisite Touch will be able to distinguish no greater
Difference between them, than that which our Blind man allow'd, when
comparing Black and White Bodies, he said, that the latter was the less
Rough of the two. Nor is every Kind of Roughness, though Sensible enough,
Inconsistent with Whiteness, there being Cases, wherein the Physical
Superficies of a Body is made by the same Operation both _Rough_ and
_white_, as when the Level Surface of clear Water being by agitation
Asperated with a multitude of Unequal Bubbles, do's thereby acquire a
Whiteness; and as a Smooth piece of Glass, by being Scratch'd with a
Diamond, do's in the Asperated part of its Surface disclose the same
Colour. But more (perchance) of this elsewhere.

15. And therefore, we shall here pass by the Question, whether any thing
might be consider'd about the Opacity of the Corpuscles of Black Pigments,
and the _Comparative_ Diaphaneity of those of many White Bodies, apply'd to
our present Case; and proceed, to represent, That the newly mention'd
Exiguity and Shape of the extant Particles being suppos'd, it will then be
considerable what we lately but Hinted, (and therefore must now somewhat
Explane) That the Depth of the little Cavities, intercepted between the
extant Particles, without being so much greater in Black Bodies than in
White ones, as to be perceptibly so to the Gross Organs of Touch, may be