US NAVAL OBSERVATORY / SCIENCE PHOTO LIBRARY US NAVAL OBSERVATORY / SCIENCE PHOTO LIBRARY
Editorial use only.
Transit circle tracking device, 20th century. US astronomer Chester Burleigh Watts (1889-1971) with the experimental tracking device which later developed into the motor drive for the 6-inch transit circle. This instrument was mounted in the place of the old 5.3-inch transit instrument. Photographed at the US Naval Observatory, Washington DC, USA.
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