27 inches; its
pitch on the scale is therefore 266/227; dividing both terms by 55, the
reduced fraction approximates to 5/4 with great accuracy, when we
consider the deviations from truth liable to occur in the delicate
measurements necessary to determine the length of a light vibration, or
the amount of quiver in a tense cord. A green wave is 0.0000211 inches
in length; its pitch is then 266/211, which reduced, becomes 4/3; in
like manner the subsequent intervals may be determined, which all prove
to be complete analogues, except, perhaps, violet, whose fraction is
266/167, which reduces nearer 16/9 than 15/8. But these small
discrepancies, which might be expected in the results of physical
measurements, do not cripple the analogy which appears now in the two
following scales:

DIATONIC OR NATURAL SCALE OF MUSIC.

C, D, E', F, G, A, B, C' D' E', &c.

1 9/8 5/4 4/3 3/2 5/3 15/8 2 18/8 10/4

DIATONIC OR NATURAL SCALE OF COLOR.

Red, Orange, Yellow, Green, Blue, Indigo, Violet.
1 9/8 5/4 4/3 3/2 5/3 16/9

Thus orange is to red what D is to C; and to resume the proportion we
used before, red is to eye as C is to ear; yellow: eye: Mi: ear; and so
on the proportion extends, till the analogy embraces chords, harmonies,
melodies, and compositions even.

We have already mentioned the chord of the tonic, and the corresponding
eye-music, red, yellow, and blue; let us consider the chord of the
dominant or 5th note, whose analogue is blue. This chord is constructed
on the 5th of the diatonic as a fundamental note, and consists of the
5th, 7th, and 9th, or returning the 9th an octave, the 5th, 7th, and 2d.
The parallel harmony among the spectral colors is blue, violet, and
orange. The name 'dominant' indicates the nature of this chord; its
often recurring importance in harmonic combinations of a certain key
make it easily recognized, and it is even more pleasing than the tonic
in its subdued character.

Out of doors this chord is preeminent in the sunset key, and the western
skies ever chant their evening hymn in the 5th, 7th, and 2d of the
ethereal music. The correspondence of the sub-dominant would be red,
green, and indigo; of the chord of the 6th, red, yellow, and indigo; and
so on, the curious mind may elicit the symmetrical to any notes, half
notes, or combinations of notes. It is evident that as a note may be
interpolated between any two of the scale