Harmonica is the name given to two simple musical instruments. The best known of these is the mouth organ. In this instrument, metal reeds are inside a case. The edge of the case has separate blowholes for each reed. The instrument is played either by blowing or sucking the air through these holes. The mouth organ is easy to play and is popular in the home.
   The second type of harmonica was invented by Benjamin Franklin. He is said to have used the idea of an Irishman named Pockrich. Franklin's instrument was a series of bowl-shaped glasses arranged on a spindle. The spindle was turned, and the rims of the glasses were moistened in a trough below. Music was made by rubbing the wet rims with the finger.
   Marianna Kirchgessner, a blind performer, made the harmonica popular in Europe in the late 1700's. Mozart composed a quintet for the glass harmonica, flute, oboe, viola and violoncello.