Fowler´s Adding Machine

Number slider

ca. 1863

George B. Fowler from Chicago, manufacturer of the early number slider, was granted US Patent 39222 for this "adding machine" on July 14, 1863. However, it is only a calculating machine without a tens transfer, consisting merely of a wooden board with eight slots. In these slots run eight strips of sheet metal, which are moved back and forth on the front side by means of scales with an adjusting pin (adjusting mechanism). The metal strips find sufficient clearance underneath the two side plates. On the back of the metal strips are engraved numbers which can be read through a row of inspection holes on the back of the instrument (result mechanism). The device cost 5 dollars. On the back of the device, the inventor named the intended target groups to whom his "Adding Machine" would be useful. Advertisements appeared in the Scientific American, and it seems that Fowler hoped to find agents who would invest in his invention in order to market it - he probably did not succeed. However, Fowler's Adding Machine was successfully imitated at the turn of the century in the form of the Locke Adder (see Inv. No. FDM 9033), which C.E. Locke patented in 1901 (US Patent 689680) and also sold for $5 at first, and later for $10. In Germany, similar devices were manufactured and sold by Justin Bamberger, Munich (cf. Omega, Inv. No. FDM 8929). However, all these devices - including the present device by Fowler - are characterized much more by their aesthetic appearance than by their functionality. On Fowler's Adding Machine, the following is mentioned as the manufacturer: "The Fowler Adding Machine Co, Manufacturers and Wholesale and Retail Dealers in Fowler's Patent Adding Machines, No. 37 Park Row, New York". On the two side plates is written: "FOWLER'S ADDING MACHINE PATENTED JULY 14th 1863" (left and right). The patent model of the Fowler's Adding Machine is located at the Smithsonian, Washington (NMAH), there are at least two more copies in private collections, including a 6-digit model.