On April 23^rd, 1873, Ferdinand Hebentanz had a calculating machine patented in Budapest that he himself called a “keyboard adding machine with an engine”. In this original design, the drive is a spring that can be wound up like we know it from clocks. When a key is pressed down, the spring power is released and can have an effect on the shafts of the result mechanism – longer or shorter, depending on the digit that has been input. Operating the keyboard is very comfortable and smooth. Winding up the spring once makes calculating possible for an astonishingly long period of time, so that this additional step does hardly count, compared to the use of other single column key adding machines. The adding machine by Hebentanz is a beautiful invention and there is an original one in the Arithmeum.

As their group project during the lecture series about the history of mechanical calculating by Professor Dr. Ina Prinz, Lena Klöckner and Felix Nöhre, both of them students of Computer Science, have made a detailed animation of this calculating machine. The short animated video provides us with a nice insight into Ferdinand Hebentanz’ ideas. Enjoy watching it!