Thomas Mill Covered Bridge over Wissahickon Creek (Picturesque America)
Centre Square Water Works, Frederick Graff, Sr. Plans, 1799
Centre Square Water Works, Latrobe Plans, 1799
PWD Drinking Water Treatment diagram
Steam engine drawing, Frederick Graff Sr., 1815
Wood truss drawbridge, Orthodox Street over Frankford Creek, 1899 [Detail]
Bridge Street Draw, July 26, 1897
Color Diagram of Plan for the Collection, Purification and Disposal of the Sewage of the City of Philadelphia
State Street pipeline construction, 1904
Electric Pump Installations at Lardner’s Point Pumping Station