Dom Bédos Short Octave?

[Benjamin Waterhouse]

Some of the engravings of small organs in Dom Bédos show keyboards with an intriguing bass layout: visually, starting on "D" and continuing up chromatically. Other keyboards miss out the first C#, which is pretty standard for the period, so maybe this mystery keyboard misses out both low C# and low D#, and to avoid starting with four white notes applies some kind of short octave layout. What would this be? Low C on the D# key? I can't find any details in the text. Does anyone have any ideas?

 

Benjamin Waterhouse