For a detailed history and description of Melville Clark player and
expression pianos, including a picture of an Apollophone with its
original phonograph, and a registry of known instruments, see the
Mechanical Music Press Melville Clark Apollo page at

http://mechanicalmusicpress.com/registry/apollo/apollo.htm 

At the end of the page are several buttons that link to the registry
(currently including information on 83 Apollos), a form for reporting
additions or corrections to the registry, and Wurlitzer factory ledgers
showing certain years of production after that company acquired the
Melville Clark factory.

Art Reblitz
http://www.reblitzrestorations.com/