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On October 22nd, 1877, the United States Coast Survey (named Coast and Geodetic Survey the following year) began "running with the utmost precision a line of levels from the Atlantic coast westward, to follow as nearly as practicable along the thirty-ninth parallel of latitude." The beginning bench mark was established on the foundation of the county courthouse at Hagerstown, Maryland. This line would extend to the Pacific Ocean. Before curtailing operations for the year, relative elevations of five bench marks were determined along a line extending twentythree miles to Williamsport, Maryland. From this modest start, over 700,000 bench mark elevations were determined over the next century. Coast Surveyors climbed mountains, forded rivers, slogged through swamps, braved desert heat, and fought off all manner of biting, stinging, and otherwise obnoxious insects during the course of this great endeavor. Hundreds of arbitrary local datums (sometimes multiple datums in large metropolitan areas) were superseded as engineers and surveyors adopted the vertical datum established by the Coast and Geodetic Survey known as the Sea Level Datum of 1929. Near universal adoption of this datum facilitated design and completion of many major engineering projects.
Albert "Skip" Theberge served as a NOAA Corps officer for 27 years prior to retirement in 1995. During that period he was primarily engaged in nautical charting and seafloor mapping but also served a stint in geodesy working on the Transcontinental Traverse project during the 1970s. For the past 15 years he has worked as a research librarian at the NOAA Central Library and has produced a number of historical works related to the Coast and Geodetic Survey (C&GS) and seafloor mapping. He also produced the NOAA History website (www. history.noaa.gov) and the NOAA Photo Library (www.photolib.noaa.gov) which includes thousands of historic photos related to the work of the C&GS.
A 3.613Mb PDF of this photoessay as it appeared in the magazine—complete with images—is available by clicking HERE