The Rennie family are mainly associated with bridges through the senior John Rennie, as Andrew Saint comments in his ODNB biography: "Rennie's crowning achievement was the trio of metropolitan bridges spanning the Thames: Waterloo Bridge, Southwark Bridge, and London Bridge, all constructed by Edward Banks (17701835) of the early contracting firm, Jolliffe and Banks, which had built many of his canals. Waterloo Bridge (181117) was his masterpiece. He was also associated with the breakwater at Plymouth and with the Kennet and Avon Canal. He performed no railway work: this was performed by his sons George and John..
John Rennie senior was born on 7 June 1761 at Phantassie, Haddingtonshire, the youngest of the nine children of James Rennie (died 1766), a farmer and owner of a brewery. A precocious interest in machinery was nurtured by the millwright Andrew Meikle (17191811), inventor of the threshing machine and improver of the windmill, who lived on the estate. Rennie worked for Meikle from when he was twelve, getting a grounding in practical mechanics. For two years (17757) he was then at Dunbar high school, where a visitor, David Loch, singled him out for his amazing powers of genius in mathematics and experimental and natural philosophy.
With Meikle's help and Rennie set himself up a millwright in 1779, but opted to combine practical work with study at Edinburgh University, where he matriculated in November 1780, continuing until 1783. Here he made friends with two eminent teachers, the chemist Joseph Black and the professor of natural philosophy, John Robison, and gained a breadth of scientific interest as well as some grasp of theoretical engineering concepts.
In 1783 Rennie took a study tour into England, making notes on canals, bridges, and machinery along his route. His destination was Birmingham, where a letter from Robison procured an introduction to James Watt, who was in need of a millwright to extend the mechanical scope of his steam engine. Watt was greatly taken with Rennie, and in the following. year Boulton and Watt offered him the job of looking after their London business and erecting the engines they supplied for the Albion Mills, the revolutionary flour mill at the south end of Blackfriars Bridge conceived and designed by Samuel Wyatt. To this end Rennie moved to London, setting up a workshop at a Thames wharf near the mill. The millwork for the twenty sets of grinding stones was supplied by Wyatt, but the substitution of much iron gearing for the customary timber was probably Rennie's
John Rennie died of liver disease on 4 October 1821 after a short illness at his home in Stamford Street, Southwark. He was buried in St Paul's Cathedral, where a plain granite slab in the crypt marks his grave. Based on Andrew Saint's ODNB entry. Jack Simmons in his Oxford Companion called the eldest Rennie "the great man among them".
Sir John Rennie was born at 27 Stamford Street, London, on 30 August 1794, the second son of John Rennie and his wife, Martha, née Mackintosh. His elder brother was George Rennie. He was educated at Dr Greenlaw's school in Isleworth, where the poet Shelley was a contemporary, and afterwards at Dr Charles Burney's school in Greenwich. In 1809 he entered his father's office and manufactory, where he acquired a practical knowledge of his profession. During the early stages of building Waterloo Bridge (181113) he was placed under the resident engineer, James Hollingsworth. He produced the working drawings for Southwark Bridge (181419) and personally selected the massive blocks of Peterhead granite for the bridge abutments. During his pupillage he also worked on the Kennet and Avon Canal and helped Francis Giles to survey ports on the Tyne and the Scottish coast. The most important of his works was the construction of London Bridge, the designs of which had been prepared by his father. After many controversies and difficulties the bridge was opened in 1831, when Rennie was knightedone of the first professional engineers to be so distinguished.
As engineer to the Admiralty, a post in which he succeeded his father up to 1831, Rennie implemented works at Sheerness, Woolwich, Plymouth, Portsmouth, and Ramsgate. At Plymouth he completed his father's great breakwater and, using convict labour, constructed the grandiose Royal William victualling yard (182735), a 16 acre complex of which 6 acres were reclaimed from the sea; the buildings and machinery alike were almost entirely supplied by Rennie Brothers. Rennie was primarily a hydraulics engineer, and much of his career was spent in adding to or altering commercial harbours and docks. In Britain these included important docks at Whitehaven and Cardiff; abroad, he built the Ponte Delgada breakwater for orange-trade boats in the Azores. He completed the drainage works in the Lincolnshire fens commenced by his father and, in conjunction with Telford, constructed the Nene outfall near Wisbech (182631). He also restored the harbour of Boston (Lincolnshire) in 18278 and made various improvements on the Welland.
A shipbuilding yard known as J. and G. Rennie was established in the 1830s at Norman Road, Greenwich, and here vessels of widely varying type were built, notably a series of early screw ships incorporating engines made at the brothers' ironworks near Blackfriars Bridge. Among Sir John's personal contributions to this side of the business was the design of fixed floats for paddle wheels.
The Rennies were also early in the field as railway engineers, designing a line from Liverpool to Manchester in 18256 on a medium gauge of 5 ft 6 in., but their plan was superseded by that of the more aggressive Stephensons. Generally, Rennie's practice in railways was not large. In 1852 he sketched out a system of railways for Sweden, and in 1855 a series of unexecuted railways and harbours for Portugal. He retired about 1863 and died at Bengeo, Hertford, on 3 September 1874. Based on Andrew Saint's ODNB entry. P.S.M. Cross-Rudkin contributed the biography in Skempton (pp. 554-69) and in Chrimes pp. 659-62.. Presumably the other Rennies have entries in Chrimes, but this will have to await escape from the bibliographical desert of Norfolk where engineering died out two centuries ago.
George Rennie was born in the parish of Christ Church, Southwark, London, on 3 December 1791, the eldest son of John Rennie (17611821) and his wife, Martha Ann, daughter of E. Mackintosh. He was educated by Dr Greenlaw at a school in Isleworth, and then went to St Paul's School. In 1807 his father sent him to Edinburgh University, where he lodged with John Playfair, the professor of natural philosophy, and studied mathematics, natural sciences, and classics.
In 1811 Rennie entered his father's office, where many great works were in progress. He travelled extensively in Europe, particularly Italy, familiarizing himself with continental engineering and architecture. In 1818, on the recommendation of Joseph Banks and James Watt, he was appointed inspector of machinery and clerk of the irons (that is, dies) at the Royal Mint, which post he held for nearly eight years. Well before his father's death in 1821, he was assisting him in bridge design. Rennie wrote a diary of progress on Waterloo Bridge, appears to have made the theoretical calculations for the iron arches of Southwark Bridge, and claimed to have made the original design for London Bridge in 1820. His government appointment precluded him from acting as engineer to London Bridge (built in 182331), however, so that honour and a knighthood went to his brother John, although George wrote the description of the bridge for Cooke's Views of the Old and New London Bridges (1833). During the 1820s he designed the bridge over the Serpentine in Hyde Park and materially improved Thomas Harrison's design for Grosvenor Bridge over the Dee in Chester. He designed the stone replacement for Thomas Wilson's iron bridge at Staines (182932). Other civil engineering schemes reported on included a proposal for Collier's Dock in the Isle of Dogs (1824), Denver sluice (1829), and Sunderland docks (1832). Rennie married, in 1828, Margaret Anne, daughter of Sir John Jackson, bt, MP; they had two sons and one daughter.
George Rennie later planned railways to connect Birmingham with Liverpool, the Vale of Clwyd line, the railway from Mons to Manège, and the Namur and Liège Railway, of which he was appointed chief engineer in 1846. He was consulted about the Liverpool and Manchester Railway following the parliamentary failure of the first bill, and organized a new survey, giving evidence in favour of the successful scheme in 1826. Although generally associated with his younger brother Sir John, he was personally responsible for early proposals for the Midland Counties Railway (18336) and Central Kent Railway (1837).
George Rennie's genius was chiefly mechanical. He superintended the manufacturing business of the family firm in Holland Street, Southwark, known at first as Rennie Brothers. After his brother Sir John retired from this side of the business about 1850 and George's sons, John Keith and George Banks Rennie, joined him, the firm became George Rennie & Sons and the factory was called the Albion ironworks. During its heyday a great variety of machinery was turned out, including the first biscuit-making machinery, corn and chocolate mills for Deptford victualling yard, and similar machines for the Royal William victualling yard, Plymouth. The firm also made the second tunnelling shield for Marc Isambard Brunel's Thames Tunnel (1835). Many orders for foreign governments were executed, including enormous iron dock gates for Sevastopol.
Rennie Brothers were also employed by the Admiralty in making engines for the Royal Navy, work which dovetailed with the establishment of the shipbuilding yard of J. & G. Rennie at Norman Road, Greenwich, in the 1830s. In all they supplied engines for between forty and fifty steamships for the British navy, and supplied an immense order for the Spanish government. Rennie was much interested in the screw-propeller. In 1840 the Rennies built the Dwarf, the first vessel in the British navy propelled by a screw; and they made the engines for the Archimedes, the first screw-driven vessel supplied to the Russian navy, in which Francis Petit Smith's screw was installed. Rennie was also interested in floating dry docks, for which he took out a number of patents.
Locomotives were made between 1837 and 1842, for railways in Britain, such as the London to Brighton and the London to Southampton lines, as well as overseas lines in Cuba, Austria, and Italy. But the works were found to be ill suited for manufacturing locomotives and this work was abandoned.
In 1822 George Rennie was elected fellow of the Royal Society, his first paper, an account of experiments made on the strength of materials having been written in 1817. This detailed tests on iron, timber, and stone which were among the earliest test results to be published on the strength of materials in Britain. Further papers followed, on the friction and abrasion of the surfaces of solids and on the friction and resistance of fluids. He presented papers to the British Association of which perhaps the most important were his review papers of 1833 and 1834, Report on the progress and present state of our knowledge of hydraulics as a branch of engineering, which were reprinted as a book in 1835. He was elected a member of the Institution of Civil Engineers in 1841. In the same year his revision of Buchanan's Mills and Millwork was published.
George Rennie was handicapped by physical disability, and in his latter life he appears to have been epileptic. In religion, he was a strict Presbyterian. He died of paralysis on 30 March 1866, at his London home in Pimlico, from the effects of an accident in the street the previous year, and was buried on 6 April at Holmwood, near Dorking.
Based on ODNB entry by Andrew Saint
and Mike Chrimes
Smith, George. The knight's tale: Sir John Rennie and the growth of railways. Backtrack, 2009, 23, 660.