> Rubber became useful after the invention of the vulcanisation
> process by Mr. Goodyear in 1939.  Before that all bellows were
> made from leather.

Note that the correct year for Mr. Goodyear's discovery of
vulcanization was 1839, and there must have been plenty of bellows
cloth in use by 1900.  I have organettes operating well on their
original bellows cloth since pre-1900.  But there were also significant
improvements in the process in the early 1900s.  For those who are
interested in vulcanization, see http://www.bouncing-balls.com, or
there's a decent article at http://en.wikipedia.org/wiki/Vulcanization

Todd Augsburger - Roller Organs
http://www.rollerorgans.com