But insteed of meeting with what I look'd for, I met with somewhat more
admirable; and that was, that I found my self utterly unable to see through
them when placed both together, though they were transparent enough when
asunder; and though I could see through twice the thickness, when both of
them were fill'd with the same colour'd liquors, whether both with the
Yellow, or both with the Blue, yet when one was fill'd with the Yellow, the
other with the Blue, and both looked through, they both appear'd dark,
onely when the parts near the tops were look'd through, they exhibited
Greens, and those of very great variety, as I expected, but the Purples and
other colours, I could not by any means make, whether I endeavour'd to look
through them both against the Sun, or whether I plac'd them against the
hole of a darkned room.
But notwithstanding this mis-ghessing, I proceeded on with my trial in a
dark room, and having two holes near one another, I was able, by placing my
Wedges against them, to mix the ting'd Rays that past through them, and
fell on a sheet of white Paper held at a convenient distance from them as I
pleas'd; so that I could make the Paper appear of what colour I would, by
varying the thicknesses of the Wedges, and consequently the tincture of the
Rays that past through the two holes, and sometimes also by varying the
Paper, that is, insteed of a white Paper, holding a gray, or a black piece
of Paper.
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