Hamilton’s 1865 Telegraph Repeater: A Patent Model With Real Relays

Image from the Smithsonian National Museum of American History's page.

A telegraph message was a series of electrical pulses sent through a wire, short ones for dots and slightly longer ones for dashes. The pulses weakened as they traveled, which limited how far a message could go. A repeater fixed that: it detected a weak signal and used a local power source to re-energize it and send it on down the line.

The model

William Hamilton of Albany, New York, sent this model to the U.S. Patent Office with his patent application. On September 12, 1865 he received patent no. 49875 for an "Improvement in Telegraphic Repeaters."

His idea was to improve automatic repeaters, which could switch between lines without an operator. He lengthened the lever arms of the two sounders so they could work a new switch and circuit design. For the model he used real relays and sounders made by A. S. Chubbuck of Utica, New York. The cylinders stand for batteries, which may be of the Grove type.

Sources

• Smithsonian National Museum of American History, Hamilton telegraph repeater patent model, Smithsonian Open Access (CC0); rewritten in hubnx's own words.