Papers mainly concerning the construction and administration of bridges, roads, piers, railways, harbours, reservoirs and canals in Scotland, 1782-1841, including correspondence of Henry Dundas, 1st Viscount Melville (1742-1811), Robert Saunders Dundas, 2nd Viscount Melville (1771-1851), and Sir Thomas Dundas, 1st Baron Dundas (1741-1820). The collection comprises letters, petitions, memorials, plans, estimates, reports, financial accounts, legal papers, trustees minutes and circulars relating to bridges including the Dee, Don, Urie, Findhorn, Montrose, Nairn, Pease, and Spey; canals including the Borrowstone Canal Navigation, the Clarence Canal, the Forth and Clyde Navigation, and the Union Canal (Falkirk to Edinburgh); ferries such as the Dysart Ferry, Queensferry, and Tay Ferries; harbours and piers notably Burntisland Harbour and Pier, Kinghorn Harbour, Hartlepool Pier, and Newhaven Pier; the Gala Water Railroad; the North Esk Reservoirs; roads in Aberdeen, Inverness, Dalkeith, Edinburgh, Glenlaidnaig, Glenlichorn, Lanarkshire, Lauriston, Perth, and Stirling.

Papers and consultancy reports, 1961-1976, mainly relating to dams and disasters, including reports on the Tannur dam, Jordan, the Roxo dam, Portugal, and the proposed dam at Scammonden, Yorkshire; report on the Clarkston disaster, Glasgow, of 21 October 1971; numerous photographs of the Aberfan disaster, Glamorgan, 1966. Obituary of Nash in Quaker Work, 1985.

Papers, 1972-1981 (some undated), on the Philippines, including typescripts, correspondence, maps, legal documents, press cuttings and other published material, some of the material produced by the Catholic Church, dealing with affairs in the Philippines, including the work of the Panamin government agency, the Chico River Basin Project (Northern Luzon) to dam the Chico River and submerge tribal villages, attempts to 'modernise' and convert minority ethnic groups to Christianity, including alleged abuses of human rights, and the political situation, including the policies of Ferdinand Marcos.

Financial records of the Staines Reservoir Joint Committee, including half-yearly accounts; journal; cash book; ledgers; register of wills and papers relating to payments to solicitors.

Corporate records of the Staines Reservoir Joint Committee, including Committee meeting attendance books, proceedings books and minutes; legal papers relating to property, rating, water supply, stocks and shares, Parliamentary issues and contracts; correspondence and debenture stock volumes.

Records of the Staines Reservoir Joint Committee, comprising progress reports from the Engineer.

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.

Photographs relating to his service in the Middle East, 1941-1943, and North West Europe, 1945, including official photographs and diagrams of the flak control tower at Nansum, Netherlands, 1945, and official photographs and report on the Möhne Dam and its defences, Germany, [1943]. Notebook relating to his work as a gunnery instructor, ND, including photographs, [1939-1945].