A Double Bosanquet Keyboard or the 2/7 keyboard

I have to thank George Secor for posting this keyboard. It illustrates how one might introduce doubled rows [running bottom left to upper right] to accommodate such tunings as using the half fifth as a generator.
Later Erv would relabel this keyboard the 2/7 keyboard as seen on page 8 of http://anaphoria.com/gralspectrum.pdf . One can see how then the generator lies in the half of 3/2 range.