Robbie commented, "I think that the story was invented by Richard
Simonton, simply to satisfy folks who asked the question, 'How did
they do it?'"
There was an advertisement by Welte which had been reprinted some
time ago in, I think, the AMICA Bulletin, showing a picture of the
piano and giving an example of how it worked. They also claimed in
the advertisement that they were able, with this electrical system,
to play back the performance instantly, and the artist didn't have
to get cold on his music before he could hear it.
Somehow, the master used electrically conductive carbon ink, wicked on
with tiny soft rubber rollers with a taper to them. The deeper the
carbon rod plunged into the mercury (presumably on a spring or some-
thing?) the harder the roller pressed the note on the paper. That
created a wider line, which, after passing through an electrical
reader, interpreted width as less resistance, hence by amplification
of some sort, was able to play the note harder.
I wonder if perhaps the trick wasn't to use saturable reactor type
magnets or solenoids, whose second winding was able to weaken or
strengthen the strike. Thus they may have found that they could weaken
the magnet to the 1st intensity normally, and then drain the saturation
coil to whatever percentage they wished by the "note resistor" printed
on the paper. I don't know but that is one possibility. I do know
that Wilcox and White had a similar system, too.
The Wilcox and White literature said:
"Here in the recording laboratories, they have sat them down
before a concert grand piano -- differing from any other grand
piano only in the fact that a cable carrying hundreds of wires
wends it's way to the reproducing device where every note is
recorded for all time. There is not the slightest attachment
to that grand piano, that could in any way affect the playing
of the artist -- the keyboard -- the action of the instrument
is as untrammeled as though he were playing on a concert stage.
And just as though he were playing on the concert stage he plays
-- with the added inspiration of the knowledge that his audience
is not limited to the concert hall -- but is all posterity."
"And then the artist sits back and listens to the reproduction
of his playing -- listens as does the audience, without thought
to the production of the composition -- and in this regard a
remarkable result has been achieved. For each time the artist
plays a certain composition, he plays it with a slight
difference. His mood, the temperature of the hall, any one of
a thousand details may affect his playing. Listening to the
reproduction of his playing, he finds that in certain passages he
has not played it as he wished -- as he actually thought he was
playing it. Dissatisfied, he again seats himself at the piano --
again his playing is faithfully recorded. 'Ah!' he exclaims as he
hears the reproduction -- 'That is what I meant'-- and when he is
satisfied, and not until then -- does he attest that master
record with his signature."