The instrument commonly known
as the harmonica (or French harp) was invented in
1829 by Sir Charles Wheatstone, who called it an
The simplest of the musical
instruments employing free reeds, the mouth
organ's reeds are set in a small narrow case of
wood or metal. For each reed there is a hole,
through which the player draws or blows with the
mouth, thereby causing the reed to vibrate and
produce a note.
The most common type of
harmonica is diatonic, having a range of about
two octaves, but harmonicas capable of playing
the full chromatic scale are not uncommon.