Water-supply 9 Bridges 4 Toll bridges 4 Canals 3 Power utilization 3 Description and travel 2 Navigation 2 more ... Pollution 2 Rates and tolls 2 Reservoirs 2 Schuylkill Permanent Bridge 2 Water 2 Water-power 2 Women in the book trades 2 Cemeteries 1 Commerce 1 Ferries 1 Inland navigation 1 Law and legislation 1 Mines and mineral resources 1 Parks 1 Ponts 1 Power unilization 1 Pumping machinery 1 Railroads 1 Tolls 1 Water rights 1 Water supply 1 less ...