Historian Ed Berlin sends this article that appeared
in the Kansas City Star, April 26, 1897, page 2.

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  The Piano of the Future
  A German Inventor Substitutes Electric Current
    for the Old Lever and Hammers.
  From the New York Journal.

   No more hammers in pianos.  The old-fashioned method of pounding
music out of wires by the aid of a wonderfully complicated system of
levers and keys, which all the world thought to be the ultimate
performer for the production of that sort of tone, has been branded
as a back number.

   Dr. Richard Elsemann of Berlin, for years a pupil of Prof. von
Helmholtz, has patented a system which does away with the levers
entirely.  He calls this new appliance the electro-phonic piano, its
distinctive principle consisting in the fact that the vibrations of
the chords are not produced by hammers, but by an electric current
and by means of microphones acting as interrupters of the current.

   All the delicate and complex mechanism of the old piano is done
away with.  The little electrical devices are arranged on the
crosspiece extending over the strings.  Upon this electric magnets
are placed so as to be only a hair's breadth from the strings.

   Pressing down the key sends the electric current into the
corresponding electromagnet.  This attracts the metallic string
below, but the microphone interrupts the current and therewith the
attraction.  The string returns to its former place, and this
continued attraction and interruption of the current is carried on,
the number of vibrations being regulated by the pitch of the string.

   The high sounds produced by the method have a decided harp tone,
and the lower and middle registers suggest the 'cello or the organ.
In reality, the installation of this new system creates a new
instrument, so different are the qualities of sound produced by
the new method and the old.  [end of article]

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I wonder if the microphone is, in reality, a tiny switch.  I believe
that in 1897 only the carbon-button microphone was available, as
employed in the telephone transmitter unit.

Yes, the instrument probably produced a sine-wave tone, like a
tuning fork.  Rather boring, I suppose!

Robbie Rhodes