US NAVAL OBSERVATORY / SCIENCE PHOTO LIBRARY US NAVAL OBSERVATORY / SCIENCE PHOTO LIBRARY
US Naval Observatory time signaller. Employee working in the Arlington Wireless receiving room. The antennas used here were dismantled in 1941, but had been used to send regular time signals from July 1913 onwards. This helped to establish official time signals used in astronomical and navigational calculations. The US Naval Observatory is based in Washington DC, USA. Photographed in July 1913.
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