1940s Pictures Atwater Kent Manufacturing Company, Philadelphia Pennsylvania Tweet Oblique Aerial View of North and South Plants, Looking East, with Powerhouse in Center Foreground (undated) Oblique Aerial View of North Plant, Looking Northwest (undated) Oblique Aerial View of North Plant, Looking North, Showing Powerhouse in Left Center and 1929 Bridge in Right Center (undated) North Plant, Southwest Elevation (November 1946) North Plant, Southeast and Partial Northeast Elevations (circa 1946) North Plant Roof, Looking Northeast (November 1946) North Plant Interior (circa 1940) North Plant Interior Showing Signal Corps Offices (undated) North Plant Interior, Basement Level, Showing Bays of Files (undated) North Plant Interior, North End of Basement Level, Showing Ductwork (1949)