Autoharp

The autoharp is a musical stringed instrument having a series of chord bars attached to dampers which, when depressed, mute all the strings other than those that form the desired chord. Despite its name, the autoharp is not a harp at all, but a chorded zither.
A design for a musical instrument that included mechanisms for muting certain strings during play.

The shape

The shape of the instrument was symmetrical, and the felt-bearing bars moved horizontally against the strings instead of vertically.



http://en.wikipedia.org/wiki/Autoharp