Business Records of James Brown, partner, Boulton, Watt & Co. (GB 582 HWUA JB)
Birmingham City Archives: Letter books, ledgers, cash books, journals, order, pattern, casting, engine, fitting and wages books, inventories etc., 1762-1895 (Reference: Boulton & Watt Collection)
Birmingham City Archives: Correspondence, ledgers, letter books and cash books and mint books, 1783-1849 (Reference: Matthew Boulton Papers)
Birmingham City Archives: Correspondence with Boulton family, 1768-1821 (Reference: Matthew Boulton Papers)
Birmingham City Archives: Watt family papers, business corresp, legal papers etc, 18th cent-19th cent (Reference: James Watt Papers)
Birmingham City Archives: Notebooks of Samuel Vale and JS Vale relating to their employment with Boulton and Watt, 19th cent (Reference : MS 2088)
Birmingham City Archives: Correspondence with Count von Bulow (photocopies), 1822-27 (Reference: MS 1619)
Birmingham Museum of Science and Industry: Drawings, blueprints and tracings, 1780-1803 (Reference: NRA 9185 Birmingham Museum)
British Library, Manuscript Collections: Misc. letters and papers of him and his son, James, 1791-1832, nd (see Index of MSS, X, 1986)
Cornwall Record Office: Correspondence mainly with Cornish agent, Thomas Wilson, 1780-1803 (Reference: DDX 208, 318)
Edinburgh University Library, Special Collections: Misc. accounts and contracts (9 items), 1787-1798 (Reference: MSS La Add 2, 5-7)
Edinburgh University Library, Special Collections: Letters to Joseph Black, 1772-88 (Reference: Gen 873-75)
Hergest Trust Archives: letters from him, his wife and his son to Mr and Mrs James Crummer, James Davies and Richard Banks, 1811- 48 (see Transactions of Radnorshire Society 1992, pp51-65)
Institution of Mechanical Engineers Library: Engine costs and drawings, 1795, 1800-02, nd (Reference: NRA 9515 Mechanical Engineers)
National Library of Wales, Department of Manuscripts and Records: letters (74) to William and Robert Mylne, 1830-47 (Reference: NLW MSS 6998E, 21805C)
Sandwell Community History and Archives Service: Correspondence and drawings, 1779-1882 (Reference: Accs 2460-2511, 3887)
Victoria & Albert Museum, Department of Designs, Prints and Drawings: Pattern book for silver and Sheffield plate, ca.1785 (Reference: E 2060-1952)
Watt Library: letters (31), 1805-34 (NRA 14668 James Watt Library)