Heyde & Büttner (Prototype)

Four-species switching ratchet machine

ca. 1883

Prototype of the calculating machine never produced in series by Gustav Heyde and Karl Otto Büttner, Dresden, DRP 26640 of September 25, 1883. Only four examples of this machine are known. A very similar prototype with the capacity 8 x 9 x 16 is in a private collection in southern Germany. Two further specimens, which differ somewhat from the present type, are in the Mathematisch-Physikalischer Salon, Dresden (Inv. No. A II 14), and in the former Brunsviga Collection, Braunschweigisches Landesmuseum (Inv. No. Zru 1879-1).

The switching principle works (according to Schillinger [2000], p. 14) as follows: The numbers are entered in the setting mechanism by means of setting slides, whereby the slides move associated segments. Depending on the position of the segments and by engaging switching ratchets, a corresponding number of teeth of the ratchet wheels (which are significantly smaller in our example than in the examples in Dresden and Braunschweig) is moved by means of intermediate wheels during the arithmetic operations to be performed, thus causing a transfer to the result mechanism. A connecting rod drive ensures smooth operation of the machine. With the help of a lever, Add./Mult. and Subtr./Div. can be adjusted. The display of the result mechanism rotates a few degrees towards the viewer (Add.) or away from him (Subtr.). While the dating of the Dresden specimen ("around 1890") is based on the statement of the old Dr.-Ing. e.h. Gustav Heyde, it must be assumed that this prototype was made at the time of the patent application around 1883. The dating of the specimen in Braunschweig is even earlier, namely 1879. In Braunschweig, the assumption was made that this was a further development of the Dietzschold machine from 1876 (see functional model FDM 6120).