Regarding Nicholas Simon' challenge, anyone with knowledge or
experience of steam locomotives will probably see a simple answer
immediately in the rocking link used to vary valve gear, including
reversing, on these engines.  The actual design would depend very
much on the configuration of the organette, but the principle is :-

The crank would connect to slotted link fixed at its other end.  A
slider, mounted in the slot of this link then connects to both the
feeder (with a single link) and to the reservoir (with one or more
links and/or levers depending on configuration), with the feeder link
at right angles to the slot, and the reservoir link in line with the
slot (approximately).

The arrangement of these links would be such that reservoir movement
slides the slider along the link so that when the reservoir is empty,
the slider is at the moving end of the slotted link, hence the crank
will be transmitting its full throw through to the feeder.  When the
reservoir is full, the slider would be at the fixed end of the slotted
link so that, even though the crank is still turning, no motion is
transmitted to the feeder.  Obviously, intermediate reservoir positions
will provide suitable throws of the feeder thus optimising the effort
put in and avoiding the need for a spill valve.

Each feeder in a multiple feeder machine would need a slotted link and
associated connections to the reservoir.  The mechanism is quite basic
and could easily be made of metal or wood, although the slotted link
and slider would be more reliable in metal (mild steel).

Does that meet your challenge, Nicholas ?

John Farmer, UK
(Archivist, MBSGB)

P.S. I suppose the next challenge is to find out whether any
enterprising and inventive organette manufacturer ever produced such
a device, if I find anything in the archives, I'll let you know.