Photo of the german mechanical engineer Franz Otto Kopp (1937 - ) while demonstrating the Hanoverian Model 2005 of the "Leibnizsche Vier-Spezies-Rechenmaschine" in 2012

[Copyright: Bernd Schwabe in Hanover under Creative Commons-License Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)]