Jacob Auch (1765-1842), who was taught by Hahn and later became the master mechanic at the Weimar Court, built several adding machines during the years 1789 and 1790, of which three have survived (today in the State Museum of Württemberg, Stuttgart, the Salon of Mathematics and Physics in Dresden, and the Mueseum Boerhaave, Leiden). It is probable that Auch had already assisted his teacher Hahn in his workshop in Echterdingen with building adding machines. In 1787 he started to work as an independent watchmaker in Vaihingen on the river Enz and soon presented his own adding machine. The decisive constructional element of his eight-place machine is the so-called tens-carry-rail, which guarantees reliable tens-carry operations. It also features a memory mechanism for storing digits. It was made for monetary calculations and thus has a non-decimal carry mechanism in the second place for converting “Kreuzer” to “Gulden” (60 Kreuzer = 1 Gulden). Subtraction can be performed using the red complementary digits. This replica is a copy of the original in Stuttgart, which Auch dedicated to the margrave of Baden. It bears the inscription “fecit: Jacob Auch Vayhingen“.