“Philadelphia Underground,” Jan. 29, 1961
“Sewer Crawlers,” January 29, 1961
1779 Revolutionary War-era map of Philadelphia and environs
Centennial Exhibition situation plan, 1876
Color Diagram of Plan for the Collection, Purification and Disposal of the Sewage of the City of Philadelphia
30th Street Sewer
PWD water tech at the Philly Home Show, 1960 (detail)
Lab tech, water cleaning demo, Philly Home Show, 1960
Oak Lane Reservoir pipeline, 1904
Upper Roxborough filter beds under construction, July 1902
