Original sentence: During his career Graf came to employ the techniques of mass production, and in 1826 he converted a former dance hall into a piano factory.Earlier, the building of pianos (just as with the earlier harpsichord) took place in small workshops.Graf played an important role in the evolution of piano making.His firm produced over 3000 instruments during Graf's lifetime
Edited sentence: (Earlier, the building of pianos, just as with the earlier harpsichord took place in small workshops.)     He purchased the "Mondscheinhaus," ("moonshine house") a formerly fashionable dance hall at 102 auf der Wieden, and converted it into a piano factory, removing the chandeliers and other accoutrements.By 1809, he was employing ten workers.By 1826, the increasing demand for his pianos had led Graf to adopt methods of mass production, an area in which he was a pioneer.His firm eventually produced over 3000 instruments during his lifetime.Katherina died in 1814, and Graf did not remarry.The Graf family had two children listed in census records:  Karalina Schelklin (born 1802), from Katherina's previous marriage, and Juliana Graf (born 1806)