Wooden Water Pipe, removed from Market Street, December 6, 1901
Centre Square Engine House, ca. 1807
“Town street scavengers from life,” Kollner, 1844
Southeast Corner of Third and Market, Philadelphia
View from front of 322 S. 44th, April 18, 1914
Volume of Sludge from 1,000,000 Gallons of Sewage
Diagram Showing Rate Between Bulk of Wet Sludge and Its Percentage Moisture
Sludge Drying Beds, Essen Nord, Germany
Grit Chamber, Essen, Germany
Effects of Expansion of Gas Bubbles in Enscher Sludge Shown in Right-Hand Cylinder