Friday the 13th seems like as good a day as any to pick nits.  I trust
everybody can find his/her favorite delete button in a trice, so here
goes:
 
Why do some people say/write 'double-manual' instead of 'two-manual'?
There's certainly nothing double about either manual.  How's about
'sextuple-cylinder' motors?  I assume that the term is a conflation of
'double', the noun referring to a two-manual harpsichord, and
'two-manual', the adjective describing such a beast.
 
I've never heard this term used by organists;  this makes me suspect
it's a recent conflation, if that it is indeed.  [By recent I mean since
the beginning of the harpsichord revival.]  Seventeenth-century
organists wrote of 'double organs';  did they also use the term 'double
harpsichords'?  Anybody done any research on the etymology of
'double-manual'?  [Opinions are welcome too....]
 
Best,
Dale