ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY
Triangulation calculation, 19th century. This diagram and text refers to the triangulation calculation carried out to determine the distance between the Royal Observatory at Greenwich and the observatory in Blackheath, London, UK. The Blackheath observatory was operated by British astronomer Stephen Groombridge (1755-1832) who moved there in 1802. The distances are in feet.
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