No other of this type is recorded. For Hartman's manufacturing technique, see John P. Lamprey, loc. cit.
Georg Hartman (1489-1564)
The extent and significance of the South German instrument-making industry in the fifteenth and sixteenth Centuries is only now becoming fully appreciated. Astronomical instruments were certainly being produced in Central Europe during the second half of the fifteenth Century as a result of the mathematical studies of of such scholars as John of Gmunden (c. 1380-1442), Georg Peurbach (1423-1461), and Johannes Mller (1436-1476), known as regionmontanus, who settled in Nuremberg in 1471. That city, enjoying excellent communications with Italy, North Germany and the Low Countries, and with an established metal-working trade, was ideally suited to become a production centre for mathematical instruments. The leading workshop producing such instruments in the early sixteenth Century was directed by Georg Hartman (the modern spelling of the name is Hartmann; the instruments are signed 'Hartman').
Hartman was born at Eggolsheim in Germany in 1489, and studied mathematics and theology in Cologne. In 1518 he visited Italy, where he became friendly with Copernicus' brother, and began designing sundials. In that same year, he was appointed vicar of St. Sebaldus church in Nuremberg, and he remained there for the rest of his life. He was a distinguished example of the scholar-craftsman, taking a full part in the intellectual life of the city, where he was a contemporary and friend of Albrecht Drer.
The number of his instruments that has survived, as well as indications concerning their manufacture, make it clear that Hartman was a pioneer of quantity production. He made a wide range of instruments, including astrolabes, sundials, quadrants, nocturnals, globes and armillary spheres, and supplied not only the aristocratic market, but also at prices accessible to poor scholars. His correspondence with Archduke Albert of Prussia has survived, revealing that he made instruments for him, and also for King Ferdinand of Bohemia, and other patrons. One of these letters reports Hartman's studies on magnetic declination, which was finally resolved by Robert Norman, and published in 1580.