Vintage, multifunction slide rule. This unit, which measures 50 cm (20”) in length, came with a leather case and the original box. Kueffel & Esser, a premier manufacturer of measurement and calculation devices began to produce high precision slide rules around 1870 and they were used extensively in scientific calculations. They came in a wide variety of sizes – as short as 12.7 cm (5”) and as long as 127 cm (50”). This model could be used for a very wide range of arithmetic and geometric calculations. Most slide rules was rapidly replaced but digital scientific calculators in the mid-1970s.
