09-019. American, "PATd MARCH 10TH 1868, signed 'C.H. WEBB. N.Y., "THE ADDER"' and serial numbered A386 on the back. As the inventor put it, the Webb adder is a "two-wheeled velocipede of figures." The instrument measures 6 3/4" long x 5 1/4" x 7/8" thick. Its two brass wheels are set in a wooden frame and partly covered by a brass plate. The large wheel adds sums up to 99; when the large wheel makes one full revolution, the small wheel moves forward one hole. This example of Webb's first adder is in very good overall condition. See Peggy A. Kidwell's article "The Webb Adder" in "Rittenhouse," Vol. 1, No. 1 for a thorough discussion of C.H. Webb and his adders.
