Approximately 20 years after Curt Dietzschold, Friedrich Weiss invented a four-species calculating machine with a switching latch mechanism, too. Apart from the specimen in the Arithmeum, only two other specimens of this machine are known, both in the Technisches Museum Wien (inventory numbers 15530, 1 and 15530, 2). The specimen in the Arithmeum is numbered 106 and seems to be the prototype, since every component has been manufactured individually.
Friedrich Weiss was a watchmaker in Vienna who was also active on behalf of sales of four-species calculating machines. The Burkhardt machine (inventory number FDM 7051) for example, bears the marking “Friedrich Weiss Uhrmacher Wien” underneath the Burkhardt logo. It can be suspected that Weiss did not only want to do the sales of the Burkhardt machines, but with this machine here also tried to launch his own construction. By using the switching latch mechanism, his attempt worked with the switching idea that Curt Dietzschold (cf. inventory number 7153) had tried to establish in Glashütte in Saxony before him. However, Weiss’s switching latch mechanism is designed in a way that saves even more space. The whole calculating mechanism is located on a horizontal shaft underneath the result mechanism. This genius idea would have made it possible to build a significantly smaller machine. Due to the success of Thomas’ arithmometer, though, Weiss stuck to the classical rectangular form.
Xenia Ewert, student of Computer Science, made a 3D animation of this unique calculating machine as a part of the lecture about the history of mechanical calculation by Professor Dr. Ina Prinz, and thus created a detailed documentation of the mechanics Friedrich Weiss invented for the first time.