This instrument consists of a mahogany case, nailed shut, with two glass windows. Four openings in a brass plate are visible below one of the windows. These windows are marked on the brass 10, 100, 1000, and 10000. There are number dials below them. According to earlier cataloging, the instrument contains an electromagnet and clockwork which operates the counter. Powered by a battery, the device could count numbers of revolutions and similar phenomena. Measuring time with a stop watch, one could calculate velocities.
A mark at the front of the top of the instrument and on the bottom reads: 39. The U.S. Geological Survey transferred the instrument to the Smithsonian in 1908. It had been used in the Water Resources Branch of the Survey.
Reference:
Accession file 48341.
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