Z; and from the Center of the Circle ADF, through Z to the
Circumference, drawing the Right Line OY, the Place of the Point Y in
the Circumference shall shew the Colour arising from the Composition of
all the Colours in the given Mixture, and the Line OZ shall be
proportional to the Fulness or Intenseness of the Colour, that is, to
its distance from Whiteness. As if Y fall in the middle between F and G,
the compounded Colour shall be the best yellow; if Y verge from the
middle towards F or G, the compound Colour shall accordingly be a
yellow, verging towards orange or green. If Z fall upon the
Circumference, the Colour shall be intense and florid in the highest
Degree; if it fall in the mid-way between the Circumference and Center,
it shall be but half so intense, that is, it shall be such a Colour as
would be made by diluting the intensest yellow with an equal quantity of
whiteness; and if it fall upon the center O, the Colour shall have lost
all its intenseness, and become a white. But it is to be noted, That if
the point Z fall in or near the line OD, the main ingredients being the
red and violet, the Colour compounded shall not be any of the prismatick
Colours, but a purple, inclining to red or violet, accordingly as the
point Z lieth on the side of the line DO towards E or towards C, and in
general the compounded violet is more bright and more fiery than the
uncompounded. Also if only two of the primary Colours which in the
circle are opposite to one another be mixed in an equal proportion, the
point Z shall fall upon the center O, and yet the Colour compounded of
those two shall not be perfectly white, but some faint anonymous Colour.
For I could never yet by mixing only two primary Colours produce a
perfect white. Whether it may be compounded of a mixture of three taken
at equal distances in the circumference I do not know, but of four or
five I do not much question but it may. But these are Curiosities of
little or no moment to the understanding the Ph nomena of Nature. For in
all whites produced by Nature, there uses to be a mixture of all sorts
of Rays, and by consequence a composition of all Colours.
To give an instance of this Rule; suppose a Colour is compounded of
these homogeneal Colours, of violet one part, of indigo one part, of
blue two parts, of green three parts, of yellow five parts, of orange
six parts, and of red ten parts. Proportional to these parts describe
the Circles _x_, _v_, _t_, _s_, _r_, _q_, _p_, respectively, that is, so
that if the Circle _x_ be one, the Circle _v_ may be one, the Circle _t_
two, the Circle _s_ three, and the Circles _r_, _q_ and _p_, five, six
and ten. Then I find Z the common center of gravity of these Circles,
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