we know is but a
Privation of Light; and accordingly Blackness seems to proceed from the
Paucity of Beams Reflected from the Black Body to the Eye, I say the
Paucity of Beams, because those Bodies that we call Black, as Marble, Jeat,
&c. are Short of being perfectly so, else we should not See them at all.
But though the Beams that fall on the Sides of those Erected Particles that
we have been mentioning, do Few of them return Outwards, yet those that
fall upon the Points of those Cylinders, Cones, or Pyramids, may thence
Rebound to the Eye, though they make there but a Faint Impression, because
they Arrive not there, but Mingl'd with a great Proportion of Little
Shades. This may be Confirm'd by my having procur'd a Large piece of Black
Marble well Polish'd, and brought to the Form of a Large Sphaerical and
Concave _Speculum_; For on the Inside this Marble being well Polish'd, was
a kind of Dark Looking-glass, wherein I could plainly see a Little Image of
the Sun, when that Shin'd upon it. But this Image was very far from
Offending and Dazling my Eyes, as it would have done from another
_Speculum_; Nor, though the _Speculum_ were Large, could I in a Long time,
or in a Hot Sun set a piece of Wood on Fire, though a far less _Speculum_
of the same Form, and of a more Reflecting Matter, would have made it Flame
in a Trice.

5. And on this Occasion we may as well in Reference to something formerly
deliver'd concerning Whiteness, as in Reference to what has been newly
said, Subjoyn what we further observ'd touching the Differing Reflections
of Light from White and Black Marble, namely, that having taking a pretty
Large Mortar of White Marble, New and Polish'd in the Inside, and Expos'd
it to the Sun, we found that it Reflected a great deal of Glaring Light,
but so Dispers'd, that we could not make the Reflected Beams concurr in any
such Conspicuous _Focus_, as that newly taken notice of in the Black
Marble, though perhaps there may enough of them be made to meet near the
Bottom, to make some Kind of _Focus_, especially since by holding in the
Night-time a Candle at a convenient Distance, we were able to procure a
Concourse of some, though not many of the Reflected Beams, at about two
Inches distant from the Bottom of the Mortar: But we found the Heat even of
the Sunbeams so Dispersedly Reflected to be very Languid, even in
Comparison of the Black Marbles _Focus_. And the Little Picture of the Sun,
that appear'd upon the White