It is not known whether Henry Hartz was a piano maker or provided the financial…
Harpsichord and square piano maker, Active in London c1760 to 1783 and also active before 1760 in Saxony. He may have worked for Silbermann before coming to London. When he arrived in London he started to make English guitars but soon turned his attention to making small pianos. We associate the name of Zumpe with the first English square pianos and his design of instrument become the blueprint for a new competitive industry of square piano making in the latter part of the 18th century. The earliest extant English square pianos were made by Zumpe in 1766 and four of these instruments are known to have survived. The present owners of the four surviving Zumpe square pianos of 1766 are:
1. Cambridge University, Emmanuel College, Cambridge, England,
2. Württembergisches Landesgewerbemuseum, Stuttgart, Germany,
3. Colonial Williamsburg Foundation, Williamsburg, Virginia, United States, and
4. National Music Centre, Alberta, Canada.
It is not known when Zumpe first started to make square pianos but it is thought that it is unlikely to be much before 1766. He was unable to keep pace with the demand for these instruments and soon after 1766 other makers turned their attention to making these instruments. In 1769 Zumpe went into partnership with Gabriel Buntebart but this partnership was dissolved by mutual agreement in 1788. The successor to Zumpe from 1783 or 1784 was Schoene & Co. when Zumpe returned to his native land.