Not much is known about the creation of this untitled, unattributed, and undated manuscript map other than it was obviously drawn to illustrate the properties of a map projection that was first developed and used in the early to mid-19th century. This type of projection was originally proposed by Ferdinand Rudolph Hassler (1770-1843), the first director of the agency that came to be known as the U.S. Coast and Geodetic Survey. The construction of this projection is based on the theoretical application of many (poly) cones to the Earth's surface (a sphere), each touching a single line of latitude (or parallel) along which there is true scale (measurement of distance). When applied to the entire globe, this projection produces a symmetrical pattern of lines where the central meridian (longitude) and the Equator are straight lines. There is no distortion along the central meridian, but distortion becomes much greater as you move further to the east and west. This projection is best adapted to large-scale mapping of small areas. Consequently, it was commonly used by the Coast and Geodetic Survey from the mid-19th century for the next 100 years as the base for its coastal charts of American waters and by the U.S. Geological Survey for its topographic quadrangles from the end of the 19th century up to the 1950s. Since the central meridian of this particular example of the polyconic projection runs through Washington, D.C., it was likely created in conjunction with the mapping activities of a federal government agency, such as the Coast and Geodetic Survey. Title supplied by cataloger. Circa 1850.