John Phillips wonders what the connection between tempo 50 on Hupfeld
rolls and paper speed in centimetres is.

I don't have a pat answer, but suppose Hupfeld checked their machines
by measuring the revolutions of the take-up spool ? All the
Hupfeld-fitted Bluthner players I've seen have had black vulcanite
take-up spools of almost the same circumference as on Aeolian and other
players: 6 inches or 15.2 cm.

Then 15 turns of the spool in a minute would pull down 15 (turns) x 6
(in) x 2.54 (cm) = 228.6 cm = 7 ft 6 in = tempo 75.

To start with, around 1898, Hupfeld were making their 73-note
"vorsetzer" (push-up) that wouldn't need harmonising with other makers'
machines, so having tempo 50 = 15 turns would be easy to remember.
Things only got awkward when they necessarily had to produce
dual-standard instruments after 1909, which initially would need to
match a predominance of 73n rolls. It followed that their 88n rolls had
to have the same speed marked on them. SM and Choralion in Berlin were
branches of EMP (Paris) and Aeolian (NY-London) so their rolls used
standard tempi.

Incidentally, after looking at the drawings for Votey's first enormous
push-up and the contemporary Hupfeld vorsetzer, I am convinced without
further argument from counsel that Aeolian were guilty of wholesale
breach of patent, not to say direct poaching of the exact design. The
little round-top 65n Pianola that appeared in 1897, of which many
thousands were made, is a clone of the first Hupfeld Phonola. Look at
the cross-sections in the Dolge book. $500,000 damages and costs !

Dan Wilson