>> By Albert “Skip” Theberge

n 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 twenty-three 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 Hundreds of arbitrary local datums (sometimes multiple datums in large metropolitan areas) were superseded as engineers and surveyors adopted the vertical datum established by the Coast and Geodetic Survey known as the Sea Level Datum of 1929.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.

Leveling a Nation

Leveling over the Tennessee River Bridge. Level party of William GibsonImage ID: theb1808, NOAA’s Historic Coast & Geodetic Survey (C&GS) CollectionLocation: Alabama, DecaturPhoto Date: 1935Credit: C&GS Season’s Report Gibson 1935

Displayed with permission • The American Surveyor • Vol. 10 No. 11 • Copyright 2013 Cheves Media • www.Amerisurv.com

Leveling a Nation

Leveling up Mount Whitney. Level party of John BrittainImage ID: theb1788, NOAA’s Historic Coast & Geodetic Survey (C&GS) CollectionLocation: Mount Whitney, CaliforniaPhoto Date: June, 1928Credit: C&GS Season’s Report Brittain 1928

Leveling a Nation. Leveling operations at Point Loma Lighthouse, the southwestern corner of the contiguous United States.Image ID: cgs01660, NOAA’s Historic Coast & Geodetic Survey (C&GS) CollectionLocation: California, San Diego, Point LomaPhoto Date: 1920Photographer: Harry Siple, USC&GSCredit: Mary Wood, Daughter of Harry Siple

Working along the Southern Pacific Railroad. Rodman at benchmark. Observing crew even with engine on right. Velocipede removed from tracks. Level party of C. A. EgnerImage ID: cgs01676, NOAA’s Historic Coast & Geodetic Survey (C&GS) CollectionLocation: CaliforniaPhoto Date: 1920Photographer: Harry Siple, USC&GSCredit: Mary Wood, Daughter of Harry Siple; C&GS Season’s Report Egner 1920

Level party trying to stay warm in Washington. Level party of Charles PierceImage ID: theb1790, NOAA’s Historic Coast & Geodetic Survey (C&GS) CollectionLocation: Washington statePhoto Date: 1931Credit: C&GS Season’s Report Pierce 1931

Checking the computations at the end of the day.Image ID: theb1794, NOAA’s Historic Coast & Geodetic Survey (C&GS) CollectionLocation: Palm Beach, FloridaCredit: NOAA National Geodetic Survey

Displayed with permission • The American Surveyor • Vol. 10 No. 11 • Copyright 2013 Cheves Media • www.Amerisurv.com