97, 98.]
§19. The Simple Colours
117
urements, the values of the wave-lengths of light of different colours have
been ascertained, and, with the aid of these data, Drobisch has tried again
to find a connection between the colour scale and the musical scale. Like
Newton, he compared the width of the colours with the intervals of the so-
called Pythagorean scale : 1 : f : § : f : f : f : V6 : 2. But since the width
of the ordinary visible spectrum, as measured by Fraunhofer, is less than
an octave, he raised each of those ratios to a certain power, which had the
value f at first, afterwards f. In this way he got the following table, in
which the wave-lengths are given in millionths of a millimetre :
f688.1
Red \
Line 11 = 687.8
/ 622.0
(7 = 655.6
Orange 1
[588.6
Yellow j
)537.7
Green \
486.1
D = 588.8
F=526.5
Blue
446.2
F = 485.6
Indigo <
420.1
Violet I
i379.8
G = 429.6
H = 396.3
In this scheme the boundaries between the colours themselves agree
fairly well with the natural ones. Possibly, it might be better to use the
major third instead of the minor third, that is, to make the whole comparison
on the bas:s of the major scale, as Drobisch himself suggested. Then the
border between orange and yellow instead of being at D in the golden yellow,
as in the above arrangement, would fall nearer the pure yellow. Even so, it
must not be forgotten that any comparison between sound waves and light
waves ceases to have any sense at all as soon as the numerical values of the
musical intervals are modified entirely by the process of raising them all to a
certain fractional power. Moreover, the spectrum is broken off arbitrarily
at both ends, because, as a matter of fact, the faint terminal colours of the
spectrum extend much farther on both sides. And, finally Newton’s division
into seven principal colours was perfectly arbitrary from the beginning and
deliberately founded on the musical analogies. Golden yellow has just as
much right to a place between yellow and orange as indigo has between blue
and violet; and the same is true with respect to yellow-green and blue-green.
Indeed, there are no real boundaries between the colours of the spectrum.
These divisions are more or less capricious and largely the result of a mere love
of calling things by names. In the author’s opinion, therefore, this comparison
between music and colour must be abandoned.
Lastly, quite recently Unger has endeavoured to establish a theory of
aesthetic colour harmony by an analogy between the wave-length ratios and
the musical intervals. In his actual statements about harmony of colours there
seems to be a good deal of truth, in large measure borrowed correctly from
works of art; but the theory itself, the analogy with the musical ratios, is
rather far-fetched. On his chromo-harmonic disc he has assembled a lot of
hues intended to correspond to the 12 semi-tones of the octave, but for this
purpose he has inserted purple reds between violet and red, although the
purples do not exist as simple colours. He makes the Fraunhofer lines G,
H, A fall in these purple hues, whereas G and H are the borders of the violet,
and A belongs to pure red. The simple colours that lie beyond violet are, as