Robbie commented in 000126 MMDigest about the Welte-Mignon "mercury
trough" dynamic recording device:

>[ I think that the story was invented by Richard Simonton, simply
>[ to satisfy folks who asked the question, "How did they do it?"

Rijn Gross of the Dutch Pianola Society (Nederlandse Pianola Veren-
iging) recently died at the age of 77.  I was told he owned a working
upright Duca, a Grotrian-Steinweg.  According to him, the story told by
old Philipps employees was that dynamics were recorded for Duca rolls
using a piano-width-long wax cylinder turning on a fine spiral so that
it could record 11 to 12 minutes of playing.  This was positioned
across the piano an inch above the strings slightly to the rear of
(towards the keyboard from) the hammers.  Normal means were used to
record actual key depression times.

The hammer shanks had a wire extension projecting ahead of the hammer,
up to one side of the strings being struck.  On the end was a conical
head like a small pencil point.  The wire was shaped so as to be sprung
to fly further up beyond the strings the harder the hammer struck them,
so that the conical head struck the wax cylinder with a force
proportional to the hammer blow.

After recording, the cylinder was removed and then slowly played back
on a pen recorder showing clearly the depth of all the cone depressions
in it, which were then related to the appropriate notes on the master
roll.

For reasons of my own, I credit this with rather more truth than the
Welte story.  Paul Morris in England makes his own wax cylinders so
people can hear themselves on a cylinder phonograph, and once you know
what you're doing, it's remarkably easy.  I would guess the device
wasn't too helpful with very soft playing, though.

Dan Wilson, London