The venerable Richard Dorf in his Audio Magazine Feb 1952 patent column walks through the Constant Martin patent technique, that apparently Miller Organs must have licenced. Dorf went on to be quite influential in electronic organs.
http://www.americanradiohistory.com/...o-1952-Feb.pdf
There is also some background in:
The Sound of Tomorrow: How Electronic Music Was Smuggled into the Mainstream by Mark Brend, and an article "Miller organ" by Hugh Davies.