Note 36 — DEVELOPMENT OF GRAVITY PENDULUMS IN THE 19th CENTURY

One was of case brass and the other of rolled iron, 68 in. long, 2 in. wide, and 1/2 in. thick. Triangular knife edges 2 in. long were inserted through triangular apertures 19.7 in. from the center towards each end. These pendulums seem not to have survived. There is, however, in the collection of the U.S. National Museum, a similar brass pendulum, 37-5/8 in. long (fig. 15) stamped with the name of Edward Kübel (1820-96), who maintained an instrument business in Washington, D.C., from about 1849. The history of this instrument is unknown.