Neither the sewers mentioned nor the distributing pipes of the public water supply were connected to individual residences. The contributions to the sewers came from the ground and the street surface. The streets were the receptacles of liquid and solid wastes and were often little more than open sewers. A promenade after dark in an ancient, medieval, or early modern city was accompanied not only by the underfoot dangers of an uneven pavement or an encounter with a footpad, but with the overhead danger from the emptying of slops into the streets from the upper windows. Sewers were used for the collection of surface water; the discharge of fecal matter into them was prohibited. The problem of the collection of sewage remained unsolved until the Nineteenth Century. TABLE 1 POPULATION TRIBUTARY TO SEWERAGE SYSTEMS ──────────────────────────────────────┬──────────┬──────────┬────────── │ 1905[2] │ 1915[3] │ 1920[4] ──────────────────────────────────────┼──────────┼──────────┼────────── Population discharging raw sewage into│ │ │ the sea or tidal estuaries │ 6,500,000│ 8,500,000│ Population discharging raw sewage into│ │ │ inland streams or lakes │20,400,000│26,400,000│ Population connected to systems where │ │ │ sewage is treated in some way │ 1,100,000│ 6,900,000│ Population connected with sewerage │ │ │ systems │28,000,000│41,800,000│46,300,000 ──────────────────────────────────────┴──────────┴──────────┴────────── The development of the London sewers was commenced early in the Nineteenth Century. The sewerage system of Hamburg, Germany, was laid out in 1842 by Lindley, an English engineer who with other English engineers performed similar work in other German cities because of their earlier experience in English communities. Berlin’s present system dates from 1860. The construction of storm-water drains in Paris dates from 1663.[5] They were intended only as street drains but are now included in the comprehensive system of the city. The first comprehensive sewerage system in the United States was designed by E. S. Chesbrough for the City of Chicago in 1855. Previous to this time sewers had been installed in an indifferent manner and without definite plan. The installation of a comprehensive sewerage system in Baltimore in 1915 marks the completion of installation of sewerage systems in all large American cities.