Hughes
The first circle are 7 Minor Key-notes, their roots having been the last 7 Key-notes that have developed. [Harmonies of Tones and Colours, First Circle are 7 Minor Keynotes, page 35c]

The second circle is a continuation of the first, shewing the 7 previously developed Key-notes are the roots of the 7 higher Key-notes. [Harmonies of Tones and Colours, First Circle are 7 Minor Keynotes, page 35c]