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Historical C&GS | Geodesy

wooden tower triangulation banner

The Triangulation Collection contains over 150 photos depicting Coast and Geodetic Survey activities in determining distances, latitude and longitude, state plane coordinates, and directions between points by the method of triangulation. The Triangulation Collection shows observers and a variety of instruments used for observing angles of triangles and other polygons; heliotropes used to reflect sunlight or electric lamps for showing lights at night; the various apparatus used to measure distances prior to the development of electronic distance measuring devices; early electronic distance measuring instruments; and the great towers that were part of the American landscape for close to 150 years that allowed the geodetic surveyors to measure angles between points tens of miles apart.

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Historical C&GS ~ Geodesy Albums - Triangulation

men on survey tower
Observing the

man with signal lamp
Heliotropes &
Signal Lamps

man on horse pulling measuring instrument
Baseline &
How Far Can You See

wooden tower illustration
Wooden Towers &
Signal Poles

men at top of tower
Bilby Steel Towers

two men hanging on tower
Towers - Whoops!

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Last Updated:
September 30, 2009