A twin-engine mechanical calculator
The 4 species, pinwheel-type BRUNSVIGA D13R is a twin engine calculator, made in 1962 by Grimme & Natalis in Braunschweig, Germany. Two individual 13R machines are joined together on a common platform, sharing the same main axis. Both machines can run in parallel or in opposite directions. The machine is handy for finding the point of intersection of 2 lines. These dual machines were in heavy use by the geometers. The exposed model is a German Bundeswehr item, probably used by the military corps of engineers. It was donated to the Computarium by the AALCD.