1. Washington Sewer-Cleaning Company, owning and operating the Knowles patent sewer cleaner for the District of Columbia Author(s): Washington Sewer-Cleaning Company, author. Publication: [Washington, D.C.?] : [Washington Sewer-Cleaning Company?], [1892?] Subject(s): Sanitary Engineering -- instrumentationDrainage, SanitaryDistrict of Columbia
2. Mercury seal traps versus sewer gas and malaria: the most perfect trap and seal against sewer gas yet invented, secured by patents Author(s): Sewer Gas Mercury Seal Co. Publication: Philadelphia : Sewer Gas Mercury Seal Co., 1883 Subject(s): Sanitary Engineering -- instrumentationMercury
