Faber Castell 63/87 R addiator pen slide rule 1940 Germany

This is a rather early, 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. 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 63/87 R system Rietz. 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 black marked AW Faber Castell sleeve (some tears). Early set in very nice condition with signs of normal use and aging darkening of the white layer. Addiator works well. 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!