When somebody wants to built a roll scanner he will probably not use
a pneumatic solution.  On the other hand if he has a reproducing piano
and wants to get data of its roll playing into a computer, the pneu-
matic approach is probably best.  Use only short tee's without much
loss.

I did not think it over thoroughly, but probably I would make the
pistons of iron and draw each one to its active state (when a hole
lets the vacuum collapse) by a little electric coil around the glass
tube.  Maybe each one regulated by voltage.  Just an idea, don't take
it too serious.

Keep on, many solutions melted together may have a good result at last.

Horst Mohr
mohr@nemeter.dinoco.DE  D-51515 Kuerten 02268/1561