Square piano

The square piano is a piano that has horizontal strings arranged diagonally across the rectangular case above the hammers and with the keyboard set in the long side, with the sounding board above a cavity in the short side. It is variously attributed to Silbermann and Frederici and was improved by Petzold and Babcock. The English and Viennese square pianos were built in many different designs, including within the action as well as general appearance, from roughly 1760. Because of the competitive industry and relative youth of the instrument design itself, experimentation ensued in the early years, creating a range of moderators (sound-altering effects) and other technical devices (knee levers; hand stops) not seen today. In London, the explosion of the trade is generally attributed to the maker Zumpe. The overwhelming popularity of his instruments was due to inexpensive construction and price. In the 1860s metal frames were developed for square pianos, meaning that higher string tensions and therefore greater volumes were possible; however the size increases meant that the upright piano design was more economical, and so the upright replaced the square as the most common home instrument. Built in quantity through the 1890s in the United States, Steinway's celebrated iron framed over strung squares were more than two and a half times the size of Zumpe's wood framed instruments that were successful a century before. Whilst many view square pianos as a 'proto-piano', because they do not have the range, volume or delicacy of touch available on modern instruments, they have a sound and playability all their own, and should be treated as a different instrument to the modern piano altogether.

Square piano (though this example is not exactly rectangular)

Square piano with open lid

Swedish painting of woman playing a square piano.

English double action with check, c. 1830 (developed from Geib, 1786

American single action with overdamper, c. 1870 (developed from Petzold, 1809)

Zumpe single action, 1766

Erard double pilot action, 1790 "Zumpe's second action" c. 1788

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Wikipedia