Magnetic Declination Isogonic Lines for the year 1870 (Variations of the Compass)
1870 (dated) 14.5 x 20 in (36.83 x 50.8 cm)
A highly unusual U.S. Coast Survey chart of the United States showing magnetic declination in the year 1870. Magnetic Declination, or as it is more commonly known Magnetic Variance, refers to the difference between true north and compass north. Magnetic variance changes both over time and from place to place, consequently accounting for compass errors was a major obstacle for many early cartographers. Today the magnetic variance in Florida is 0 degrees, but when this chart was made in 1870, the 0 degree point was in South Carolina. A cartographer traveling north from South Carolina to Maine would find that his compass miscalculated north by nearly 18 degrees! In other places the variance is even more extreme. Compiled under the direction of A. D. Bache, Superintendent of the Survey of the Coast of the United States and one of the most influential American cartographers of the 19th century.
The Office of the Coast Survey, founded in 1807 by President Thomas Jefferson and Secretary of Commerce Albert Gallatin, is the oldest scientific organization in the U.S. Federal Government. Jefferson created the "Survey of the Coast," as it was then called, in response to a need for accurate navigational charts of the new nation's coasts and harbors. The spirit of the Coast Survey was defined by its first two superintendents. The first superintendent of the Coast Survey was Swiss immigrant and West Point mathematics professor Ferdinand Hassler. Under the direction of Hassler, from 1816 to 1843, the ideological and scientific foundations for the Coast Survey were established. These included using the most advanced techniques and most sophisticated equipment as well as an unstinting attention to detail. Hassler devised a labor intensive triangulation system whereby the entire coast was divided into a series of enormous triangles. These were in turn subdivided into smaller triangulation units that were then individually surveyed. Employing this exacting technique on such a massive scale had never before been attempted. Consequently, Hassler and the Coast Survey under him developed a reputation for uncompromising dedication to the principles of accuracy and excellence. Unfortunately, despite being a masterful surveyor, Hassler was abrasive and politically unpopular, twice losing congressional funding for the Coast Survey. Nonetheless, Hassler led the Coast Survey until his death in 1843, at which time Alexander Dallas Bache, a great-grandson of Benjamin Franklin, took the helm. Bache was fully dedicated to the principles established by Hassler, but proved more politically astute and successfully lobbied Congress to liberally fund the endeavor. Under the leadership of A. D. Bache, the Coast Survey completed its most important work. Moreover, during his long tenure with the Coast Survey, from 1843 to 1865, Bache was a steadfast advocate of American science and navigation and in fact founded the American Academy of Sciences. Bache was succeeded by Benjamin Pierce who ran the Survey from 1867 to 1874. Pierce was in turn succeeded by Carlile Pollock Patterson who was Superintendent from 1874 to 1881. In 1878, under Patterson's superintendence, the U.S. Coast Survey was reorganized as the U.S. Coast and Geodetic Survey (C & GS) to accommodate topographic as well as nautical surveys. Today the Coast Survey is part of the National Oceanic and Atmospheric Administration or NOAA as the National Geodetic Survey.
Report of the Superintendant of the United States Coast Survey, Washington, (1870 edition).
Very good. Minor wear, toning, and verso reinforcement on some of the original fold lines. Blank on verso.