suspected. Let us take as our standard of colours the series given by the disintegration of white light, the so-called spectrum: as our standard of musical notes, let us take the natural or diatonic scale. We may justly compare the two, for the former embraces all possible gradations of simple colours, and the latter a similar gradation of notes of varying pitch. Further, the succession of colours in the spectrum is perfectly harmonious to the eye. Their invariable order is— red, orange, yellow, green, blue, indigo, and violet; any other arrangement of the colours is less enjoyable. Likewise, the succession of notes in the scale is the most agreeable that can be found. The order is—C, D, E, F, G, A, B; any attempt to ascend or descend the entire scale by another order is disagreeable. The order of colours given in the spectrum is exactly the order of luminous wave-lengths, decreasing from red to violet. The order of notes in the scale is also exactly the order of sonorous wave-lengths, decreasing from C to B."
"Now comes the important question—Are the intermediate colours of the spectrum produced by vibrations that bear a definite ratio to the vibrations giving rise to the intermediate notes of the scale? According to our knowledge up to this time, apparently not."
"Comparing wave-lengths of light with wave-lengths of sound—not, of course, their actual lengths, but the ratio of one to the other—the following remarkable correspondence at once comes out:—Assuming the note C to correspond to the colour red, then we find that D exactly corresponds to orange, E to yellow, and F to green. Blue and indigo, being difficult to localise, or even distinguish in the spectrum, they are put together; their mean exactly corresponds to the note G: violet would then correspond to the ratio given by the note A. The colours having now ceased, the ideal position of B and the upper C are calculated from the musical ratio."
This quotation on vibrations will be seen to agree with the laws which I have gained. The fact that six of the notes of keyed instruments are obliged to act two parts, must prevent the intermediate notes bearing a definite ratio of vibrations with the intermediate colours of the spectrum. I name the note A as violet, and B ultra-violet, as it seemed to me clearer not to mention the seventh as a colour.
The fountain or life of musical harmonies and colours is E, or yellow; the root B, or ultra-violet: these being, in fact, tints and shades of white and black. Ascending, they partake more of white; descending, of black: the former drawing tones and colours higher, the latter lower.