Keywords: Heliotrope2.jpg en Heliotrope being used in western United States NOAA's http //www photolib noaa gov/cgs/index html Historic C GS Coast and Geodetic Survey Collection Image ID http //www photolib noaa gov/htmls/theb1634 htm theb1634 http //www noaa gov/ US National Oceanic and Atmospheric Administration ~ 1878 PD-USGov Triangulation Heliotrope |