This doesn't qualify as "undiscovered" but still might qualify as an
extinct instrument.  If I'm not mistaken its organ stop was called a
"V'olin".  It was a stop on a Robert Morton pipe organ and was meant
to simulate a real violin.

The instrument had 61 physical strings and a long tapered cylinder of
rosin that turned.  Pneumatic fingers pressed the string(s) against the
tapered roller.  Unlike organ actions, it was vacuum driven with a pump
that looked very similar to an Ampico box pump.  I had the good fortune
to see one of these Rube Goldberg instruments at a neighbor's house
about 40 years ago.  Dick Schroeder [Los Angeles organ technician] had
one and was going to install on his Robert Morton organ.

Has anyone else seen or know the whereabouts of any or if any still
exist at all?  As I understand they didn't fill the bill and most found
their way to the landfills, as unfortunately they were not loud enough
to compete with the rest of the organ.

Tim L'Amoureux

P.S.  I want one! :-)