If you stroke the edge of a drinking glass with the fingertips you will hear a faint musical note. Concerts on sets of wine glasses, played in this way, and filled with water to tune them to different notes, featured in musical life in Britain in the mid-18th century. The armonica is a mechanised version of these 'musical glasses'. It was invented in 1761 by Benjamin Franklin, an important figure in the history of the United States. He was inspired to create the armonica after hearing a concert for the musical glasses while on a visit to Britain earlier that year. The armonica's glass bowls of graduated sizes are tuned to the notes of a chromatic scale, and are mounted on an axle turned by a treadle mechanism. Later on, the row of glasses was suspended over a trough of water, which wetted them as they were turned, so that they produced the optimum sound of crystalline clarity when they were stroked. Although there was some interest in the armonica in North America, the instrument had more enthusiastic audiences in northern Europe, including writers of the era such as Goethe, and it remained in use until after 1825. Both Mozart and Beethoven composed music for the armonica.