# Dictionary of National Biography, 1885-1900/Rennie, John (1794-1874)

​RENNIE, Sir JOHN (1794–1874), civil engineer, second son of John Rennie [q. v.], and brother of George Rennie (1791–1866) [q. v.], was born at 27 Stamford Street, Blackfriars Road, London, on 30 Aug. 1794. He was educated by Dr. Greenlaw at Isleworth, and afterwards by Dr. Charles Burney at Greenwich. He subsequently entered his father's manufactory in Holland Street, Blackfriars Road, where he acquired a practical knowledge of his profession, and in 1813 he was placed under Mr. Hollingsworth, resident engineer of Waterloo Bridge, the foundations of which he personally superintended. In 1815 he assisted his father in the erection of Southwark Bridge, and in 1819 he went abroad for the purpose of studying the great engineering works on the continent. On the death of his father in 1821 he remained in partnership with his brother George, the civil engineering portion of the business being carried on by him. The most important of his undertakings was the construction of London Bridge, the designs for which had been prepared by his father. The bridge was opened in 1831, when Rennie was knighted, being the first of the profession since Sir Hugh Myddleton to be thus distinguished. As engineer to the admiralty, ​a post in which he succeeded his father, he completed various works at Sheerness, Woolwich, Plymouth, Ramsgate, and the great breakwater at Plymouth, of which he published an ‘Account’ in 1848. Many years of his life were spent in making additions and alterations to various harbours on different parts of the coast, both in England and in Ireland. He completed the drainage works in the Lincolnshire fens commenced by his father, and, in conjunction with Telford, constructed the Nene outfall near Wisbech (1826–1831). He also restored the harbour of Boston in 1827–8, and made various improvements on the Welland.
Although he was early in the field as a railway engineer, he and his brother having designed a line from Liverpool to Manchester in 1825–6, his practice in this department was not very large. In 1852 he laid out a system of railways for Sweden, for which he received the order of Gustavus Vasa, and in 1855 he designed a series of railways and harbours for Portugal, none of which were, however, carried out.
Rennie was elected a member of the Institution of Civil Engineers on 25 June 1844, and he became president on 21 Jan. 1845, retaining the office for three years. His presidential address in 1846 was a complete history of the profession of civil engineering (Proc. Inst. Civ. Eng. v. 19). He also contributed papers on the drainage of the level of Ancholme, Lincolnshire (ib. iv. 186), and on the improvement of the navigation of the river Newry (ib. x. 277). He published, besides his ‘Account of Plymouth Breakwater,’ 1848, ‘Theory, Formation, and Construction of British and Foreign Harbours,’ 1851–4.
Rennie was the last of his race, and formed a connecting link between the Brindleys, the Smeatons, the Rennies, and the Telfords of the old system with the Stephensons and the Brunels of the new. He retired from the active duties of his profession about 1862, and died at Bengeo, near Hertford, on 3 Sept. 1874, just after completing his eightieth year. There is a portrait by James Andrews at the Institution of Civil Engineers, Great George Street, and an engraving appears in his ‘Autobiography.’
R. B. P.