From the book, "Piano", by David Crombie; there are two photographs
with this caption:

  "Dulcitone by Thomas Machell & Sons, Glasgow, c.1920."

  "The 'Dulcitone' was invented by Thomas Machell in 1860, although not
  perfected until 1880.  It is usually described as a 'tuning-fork'
  instrument.  This five-octave example uses a down-striking version of
  the English grand action.  The inverted action assembly can be seen
  on top of the casework in the picture below.  The jack (or hopper) is
  beneath the front of the key.  Each hammer strikes a U-shaped metal
  bar mounted in rubber.  The sound bears little relationship to that
  of a piano but the instrument feels similar to play.

  The lack of a real frame makes the Dulcitone relatively light and
  portable.  It was the most popular of the early 'tuning-fork'
  instruments.  Other examples included the 'Typophone', the 'Adiaphon'
  and the 'Euphonium'.  The most famous, however, was the electric
  piano designed by Harold Rhodes in the late 1950s."

Bob Fitterman