Documents relating to the design of William Congreve's hydro-pneumatic locks on the Regents Canal, 1812-1814. [17 items. Relating to the unsuccessful design of a canal lift by William Congreve and including a letter from Congreve to Henry Maudslay, descriptions by Congreve of the working of the lock, draft letters from Maudslay & Co. to the Canal company, estimates etc.]