musical instrument that was popular for domestic music-making from the time of its invention in the mid-18th century (possibly by the Saxon organ-builder Ernst Christian Friderici) to about 1860 in Europe and to about 1880 in the United States. This type of piano was introduced in France by the instrument-builder Sebastien Erard (c. 1777) and was already popular in England after about 1760, thanks largely to the efforts of Johann Christoph Zumpe and other immigrant German builders, who concentrated on building square pianos with a simple, so-called single action (mechanism) that was adequate for the demands of most salon music.