Nestler 20/3 Kiel Schwerdtfeger naval slide rule 1930 Germany

Nestler nr. 20/3 Kiel specially made for U-boat calculations to be used by student from the German Navy school in Kiel during 1920-1950. It is a simplified Rietz model with a special cursor and additional marks for easy naval calculations. The information on the back is also altered to fit specific needs. Only sold by a few select retailers in the school area like this one from Schwerdtfeger from the city of Westermünde. Both slide rule and cardboard holder are signed and in very good condition with normal signs of use and age only. Made ca 1930. The slide rule measures a standard 29,5 cm or 12 inches in length. Do check the video below on how to work your vintage man tool : slide rule operation instructions!