TITLE BLOCK Map of a reconnaissance of the approaches to Philadelphia showing the positions and lines of defence on the north front of the city. Made under the direction of A.D. Bache, Supt. U.S. Coast Survey, Engineer in Charge of the Defences ; general field reconnaissance by George Davidson, Assistant U.S. Coast Survey ; details by George Davidson ; assisted by C.M. Bache … [et al.] ; map plotted and drawn by George Davidson ; assisted by A.R. FauntLeRoy and W.E. Weber.
DATE 1863
EXTENT Northern Philadelphia and small part of Montgomery County, Pennsylvania. Covering the watersheds of the Wissahickon Creek (and its tributaries the Cresheim and Monoshone), Frankford Creek (Tacony, Little Tacony, Wingohocking, and Rock Run), Wissinoming Creek, and Pennypack Creek (Sandy Run).
SOURCE Library of Congress
WHY DO I LIKE THIS MAP? A military history buff would like that this map shows Civil War batteries, both built or planned, that were part of the planned defenses of the city in case of a Confederate Army attack. For me, the attraction are the details of the streams, a number of which were later subsumed into the city sewer system. The delineation of elevation is also of interest, as I have long dreamed of creating a map of the city that shows historic elevations before the streams were buried, high ground was cut down, and valleys and low land filled in – actions that dramatically altered the lay of the land. Some earlier maps of the city use graphic markings to indicate hills and valleys – for examples, see Ellet (1843) and Hills (1796) – but this is the first wide-scale map that I have found that uses contour lines to indicate elevation.
MORE INFORMATION The Library of Congress has at least two versions of this map, both pieced together from ten sections of various sizes. I featured the best one here, where the sections are matched up more exactly. Its overall size is 153 x 265 cm, which, if you are metrically challenged (as I am), converts to 60 x 104 inches. The .jpeg files presented here are reduced in size and quality from the original uncompressed 1.8 gb tif version available for free download from the Library of Congress.
OTHER SIMILAR MAPS The Library of Congress has thousands of maps from the Civil War era. Among them is a map showing the western defenses of Philadelphia which has similar topographic details and is even larger in size than the one featured on this page.