8. And Fourthly, whereas among the Dispositions we attributed to White
Bodies, we also intimated this, That such Bodies are apt, like _Speculums_,
though but Imperfect ones, to Reflect the Light that falls on them
Untroubled or Unstain'd, we shall besides other particulars to be met with
in these Papers, offer you this in favour of the Conjecture; That in the
Darkned Room several times mention'd in this Treatse, we try'd that the
Sun-beams being cast from a Coloured Body upon a neighbouring White Wall,
the Determinate Colour of the Body was from the Wall reflected to the Eye;
whereas we could in divers cases manifestly Alter the Colour arriving at
the Eye, by Substituting at a convenient Distance, a (conveniently)
Colour'd (and Glossy) Body instead of the White Wall. As by throwing the
Beams from a Yellow Body upon a Blew, there would be Exhibited a kind of
Green, as in the Experiments about Colours is more fully Declar'd.
9. I know not whether I should on this Occasion take notice, that when, as
when looking upon the Calm and Smooth Surface of a River betwixt my Eye and
the Sun, it appear'd to be a natural _Speculum_, wherein that Part which
Reflected to my Eye the Entire and defin'd Image of the Sun, and the Beams
less remote from those which exhibited That Image, appear'd indeed of a
great and Whitish Brightness, but the rest Comparatively Dark enough: if
afterwards the Superficies chanc'd to be a little, but not much troubled,
by a gentle Breath of Wind, and thereby reduc'd into a Multitude of Small
and Smooth _Speculums_, the Surface of the River would suitably to the
Doctrine lately deliver'd, at a Distance appear very much of Kin to White,
though it would lose that Brightness or Whiteness upon the Return of the
Surface to Calmness and an Uniform Level.
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