y or length of the wave, and certain combinations
of wave lengths will be harmonious (beautiful), and others will not
be. This is a matter of scientific fact; it is not a notion. The
mathematical relations of color waves have been calculated as
accurately as the relations of sound waves have been. It is possible
to make combinations of mathematical figures which shall represent a
series of harmonious color waves. And it is possible to measure the
waves radiated from a piece of bad coloring and prove them,
_mathematically_, to be bad color.

It is a satisfaction to the artist to know that this is so; because
although he will never compose color-schemes by the aid of
mathematics, it gives him solid ground to stand on, and it diminishes
the assurance of the man who claims the right to assert his opinion on
color because "one man's taste is as good as another's." It is also
encouraging to the student to know it, because he then knows that
there is a definite knowledge, and not a personal idiosyncrasy, on
which he can found his attempts to cultivate this side of his artistic
life.

=Color Composition.=--The artist's problem in color composition is
analogous to that of line and mass, but is of course governed by
conditions peculiar to it. The qualities which derive from line and
mass are emphasized or modified by the management of color in relation
to them. The painter in this direction uses the three elements
together. Contrast and accent are attributes of color. Dignity and
weight, as well as certain emotional qualities, such as vivacity and
sombreness, may give the key to the picture in accordance with the
arrangement of its color-scheme.

The mass may be simplified and strengthened, or broken up and
lightened, by the color of the forms in it. By massing groups of
objects in the same color, or by introducing different colors in the
different forms in the same group, the mass is emphasized or weakened.
So in line, the same color in repetition will carry the line through a
series of otherwise isolated forms, and effect the emphasis of line.
Masses can be strung into line, like beads, on a thread of color. In
the great compositions of the old Venetian painters this marshalling
of color groups constituted a principal element. The decorative unity
of these great canvases could have been possible in no other way.

As I have said, the key of the color-scheme has a direct emotional
effect, so adding to the power and dignity o