Rare long out of print elegant reprint.  
Added a reprint of a tubing schematic recently found as well as a great copy of an original regulation card found in one of the pianos. 

The Melville Clark Apollo, Apollo-X and Art-Apollo player piano that use special QRS "RED X" rolls.
The Amphion produced version is called the DYNACHORD and is the same design/layout as the Art-Apollo.

New old stock. 
3 1/2"  x 6" 
18 pages with fold out diagrams & single sheet tubing diagram of expression system plus card stock printed regulation spec sheet.
Single sheet tubing schematic for the expression system.