The Water and Drainage History of Philadelphia, Part 6
The Water and Drainage History of Philadelphia, Part 5
The Water and Drainage History of Philadelphia, Part 4
The Water and Drainage History of Philadelphia, Part 3
The Water and Drainage History of Philadelphia, Part 2
Typhoid bacteria diagram, 1905
Half a Century of Clean Water
Effects of Expansion of Gas Bubbles in Enscher Sludge Shown in Right-Hand Cylinder
‘Gillette, All By Himself, Gets Fine New Idea On Germ Slaying’
State Street pipeline construction, 1904
