Records of the South London Waterworks Company (later the Southwark and Vauxhall Water Company) including papers relating to shares; minutes of Director's meetings; stock certificates; papers relating to works and papers relating to a lawsuit.

Records, 1872, of Rosario and Cordova Water Works Company, comprising prospectus, memorandum of association, and contract for acquisition of concession and construction of works, with plans attached.

Record books, 1902-1905 and 1921-1922, relating to the examination of water and water supplies.

Papers of Professor William Cawthorne Unwin, 1856-1952, comprising correspondence, principally concerning engineering matters, 1856-1931, 1950,1952, notably with Edward Dean Adams, including the Niagra Falls Scheme, 1890-1929, Sir Benjamin Baker, including the Forth Bridge, dam schemes, 1882-1898, Sir William Fairbairn, including experiments, appointments, 1856-1874, Thomas Hardy, concerning astronomy, 1881, Imperial College, 1910-1926 (as representative of the Institution of Civil Engineers);
research papers, 1859-1924, notably Fay and Newall brakes, 1859, observations on the Thames, 1882-1883, Nile Project Committee, 1919, dam schemes, 1899-1905;
speeches and addresses to various institutions, including presidential addresses to the Institution of Civil Engineers, 1912, and Institution of Mechanical Engineers, 1916; engineering drawings, 1875-1906, of apparatus, machinery, sections of the Thames, Telok Ayer key wall, Singapore; two portraits of Unwin, undated;
additional material, comprising papers relating to Windsor Water Works arbitration, 1884; reports on compression gauges, 1886-1887; Birmingham dams, 1895; notes on dam theory, 1905; papers relating to Stockport water supply and Kinder Dam, 1905; notes relating to schemes for Niagra and central London.

Papers, 1881-1891, of Donald James Mackay, 11th Baron Reay, as Governor of Bombay, comprising correspondence, memoranda, petitions and other papers, 1884-1889 and undated, on A'bkari administration (a system of licences for the distillation and sale of spirits in Bombay); correspondence, memoranda, minutes, reports and other papers, 1881-1891 and undated, relating to military and naval subjects; correspondence, memoranda, minutes and reports, 1885-1890 and undated, on education; correspondence and other papers, 1881-1891 and undated, on agriculture; correspondence and other papers, 1884-1889 and undated, on sanitation and water works; correspondence and papers, 1884-1891 and undated, on various other subjects including administration, hospitals, irrigation, railways and finance; addresses of welcome to Lord Reay, 1886-1890 and undated; a drawing of Bombay harbour and accompanying manuscript plan, undated; manuscript map of Karachi Harbour Board, 1887.