Anybody who has played Wurlitzer 165 rolls on a dual-tracker organ
has noticed that early rolls can't be teamed up with later rolls
because of their Tempo difference.

 [ Within this context, "Tempo" denotes the speed of the music
 [ medium (e.g., feet per minute), not the musical beats per minute
 [ (the "metronome setting").  -- Robbie

Obscuring this problem is the fact that the numbering of Wurlitzer
evergreen rolls 6501 to 6537 duplicate the numbering of its early rolls
issued from 1914 to April 1918, even though the evergreens appeared in
1923.

The reason for the Tempo problem is that early rolls were cut to a
basic roll tempo that is faster than later rolls, meaning that playing
those rolls requires that fewer inches of paper per minute travel over
the tracker bar.

Rich Olsen, who arranged many good Wurlitzer 165 rolls from 2007 to his
death in 2013, had studied this tempo change and had concluded that it
took place around 1923.  Terry Hathaway's huge, new APP rollography,
now posted on the Mechanical Music Press website

  http://www.mechanicalmusicpress.com/registry/wurlitzer/mr_wapp65.htm 

contains a photocopy of a 1923 document that confirms Rich Olsen's
theory.  It is a memorandum issued to the Wurlitzer Roll Department
by General Superintendent Walter H. Wendell ordering an immediate
change in roll production methods to address numerous complaints that
Wurlitzer had been receiving from its roll customers concerning Tempo
problems.

Why was this change in its roll-cutting practice not announced by
Wurlitzer to its customers?  Beyond the fact that the instructions
issued by Wendell are very technical, Wurlitzer probably saw no need
to announce a course correction of this kind because of the company's
philosophy advertised in its Monthly Roll Bulletins, "It pays to buy
new music."  Wurlitzer didn't want its customers to continue playing
old rolls, but to toss them out in favor of the latest new hits.

Matthew Caulfield
Irondequoit, New York