There is an _excellent_ 8-page article by Ron Bopp on the Testophone
in the Spring 1997 issue of the MBSI publication "Mechanical Music".
It includes patent diagrams, many photos of the mechanisms and
different models, and a very good illustrated description of how they
operate.  They came in 3, 4, 6, and 8-horn models, and were played by
either disc or cylinder!

I've had good luck obtaining back issues from MBSI -- contact Ted &
Irene Leverett, 3621 Curtland Pl. NW, Concord, NC 28027.  They're
a bargain!

And I suppose I should also put in a plug for MBSI (and MBSGB)
membership -- their excellent publications are well worth the annual
dues!

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