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
Grit Chamber, Essen, Germany
Sludge Presses for Grease Recovery, Bradford, England
Drain water from sludges obtained from sedimentation, septic and Emscher tanks
A Day in the Ma’sh – Oil Refinery
Bridge Street Draw, July 26, 1897
“Philadelphia Underground,” Jan. 29, 1961
Color Diagram of Plan for the Collection, Purification and Disposal of the Sewage of the City of Philadelphia