Faber Castell 63/91 R SB addiator pen slide rule 1940 Germany

This is an earlier, ca. 1940’s Faber Castell slide rule that has a double function. It is a combination of slide rule on one side and an addiator on the other side. On top of that it was a special order for the Schäffner & Budenberg Company from Magdenburg Germany and signed as such. Also the original sleeve is signed with the company logo. The addiator is a predecessor of the basic handheld calculator (as is the abacus) with function that allows for quick addition and subtraction of amounts. The slide rule itself is more the predecessor of the scientific electronic calculator. This slide rule is a very basic early version with model name 63/91 R. It is made of bamboo with celluloid top and metal cursor with plastic glass. It comes complete with the full metal pen and the original green sleeve. Early set in very good condition with small signs of normal use and age (little darkening of the white layer). Addiator works well, hardly used. It measures ca. 15,5 cm or ca. 6 1/4 inches. Check the attached video on how to work your vintage man tool : slide rule operation instructions!