Hughes
The twelve keys meeting by fifths, one series modulating through seven octaves, keys not mingled
—The twelve veering round, the intermediate notes not coloured
—The keys of A and E meeting the intermediate notes coloured in musical clef, . . . . . 39 [Harmonies of Tones and Colours, Table of Contents3 - Harmonies]

The second circle is a continuation of the first; the seven previously developed key-notes become, as before, the roots of seven higher. The uncoloured intermediate notes are in the same way complementary pairs. [Harmonies of Tones and Colours, Diagram X - Minor Keynotes Developing by Sevens, page 35a]