Screwpiles: The Forgotten Lighthouses

Maps, Charts, and Mapping Technology On February 10, 1807, President Thomas Jefferson signed an act that authorized him “to cause a survey to be taken of the coasts of the United States, in which shall be designated the islands and shoals, with the roads or places of anchorage, within twenty leagues of any part of the shores of the United States.”

At that point in our history, our coastline extended from New Hampshire to Georgia. 13

Survey work was started, but it did not progress very well. In 1832, the Coast Survey was established and reorganized under the Treasury Department. By then, our coastline had extended to Maine through Louisiana. The methods of triangulation and soundings were reestablished, and Ferdinand Hassler was appointed superintendent. He immediately set about systematically surveying the coast from New England to the Chesapeake Bay. He was succeeded in 1843 by Alexander Bache, who expanded the survey effort.

Diagram of Hassler’s original triangulation from 1817 and 1833 to 1834

The resulting maps, charts, and surveys were reliable and widely available. The Coast Survey added important discoveries, such as a previously unknown channel into New York Harbor.

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