Map of a reconnaissance of the approaches to Philadelphia showing the positions and lines of defence on the north front of the city /

Topographic map of the northern part of Philadelphia County and small adjacent part of Montgomery County showing proposed 1st-, 2nd-, and 3rd-order Civil War batteries.
Signed in handwriting: George Davidson, Asst. Engr. Fortifications.
Pen-and-ink, red ink (contours), and watercolors.
Former ownership rubber-stamping below title: U.S.C. & G. Survey, Library and Archives, no. 127.
"No. 2865X" and "854W 1863" (former Coast Survey numbers) handwritten in ink on adhesive labels at corner of each sheet.
Imperfect: brittle, water-stained along left and right sides.
Includes note added in Davidson's handwriting.
LC Civil War Maps (2nd ed.), 358.25
Available also through the Library of Congress web site as raster image.