The name of John Rennie is familiar in connexion with Waterloo Bridge, London Bridge and other bridges. His work as a builder of canals, docks and harbours was probably more important, although his ideas were sometimes wasted by official lack of enterprise
THE story of the early days of John Rennie, the son of a farmer of Phantassie, East Lothian, resembles that of other pioneer engineers; for, even when he was a small boy, “making things” was more attractive to him than play. He was born on June 7, 1761. From the age of six his chief delight was to haunt the workshop of a millwright, Andrew Meikle, the inventor of the threshing machine. So keen was the boy on mechanical work that, at the age of twelve, he begged to be allowed to leave school and to enter the workshop.
Wisely, this concession was made; but, equally wisely, he was taken away after two years and sent to the High School at Dunbar. Here he so distinguished himself that, when not yet seventeen, he was recommended to succeed his mathematics master when the master received another appointment. This opened up prospects of a secure and respected future; but Rennie, though he filled the position for six months, felt the urge for building much too strongly to settle down as a schoolmaster. Back home he went, to frequent Meikle’s workshop once more and then to start as a millwright himself.
At the age of nineteen he had as much work as he could get through, but now the scientific side of his calling began to appeal to him, and he decided to enter the University of Edinburgh, and support himself by working in the long summer vacation. There was then nothing that corresponds to the present-day engineering curriculum, but Rennie entered the classes in what would now be called physics and mechanics under Dr. Robison, a friend of James Watt. So, alternately working as a millwright and studying hard, learning French and German, Rennie remained at Edinburgh until 1783. He then made a journey south to see what English engineers were doing. He visited the Bridgewater Canal, a much talked-of work of Brindley’s, some dock construction works at Liverpool, and Boulton and Watt’s famous factory at Birmingham.
The condensing steam engine was by this time fully established, and a notable pair were to be installed in a large new flour mill in London. After his visit to Birmingham, Rennie was appointed to take charge of the fitting up of the mill, which was on a scale hitherto unknown. The task of designing and erecting the plant occupied Rennie for nearly four years, the mill being finished in 1788. It was described, on good authority, as having “effected an entire revolution in millwork generally”. The Albion Mills, at one end of Blackfriars Bridge, London, were unfortunately entirely destroyed by fire early in 1791. About the end of 1791 Smeaton retired from practice and Rennie came to be regarded as his successor. Soon afterwards Rennie was occupied in a number of canal undertakings. His first work of this kind in England was a canal between Reading and Bath, followed by one at Rochdale, Lancashire. In both canals a large number of locks was necessary. Several other canals were surveyed and built by Rennie, this branch of his work becoming more or less a matter of routine. More important, because the subject had been for long shamefully neglected, was his drainage of the Lincolnshire and Cambridgeshire Fens. Few travellers nowadays, seeing these fertile districts from the train, can form an adequate idea of their submerged and desolate condition at the end of the eighteenth century. Attempts at drainage had been made previously, but they seemed abortive, whereas Rennie’s well-planned schemes, carried out between 1799 and 1821, permanently reclaimed immense swamps and wastes.
Perhaps the work with which Rennie is most commonly identified is Waterloo Bridge, across the River Thames. This bridge has been pulled down, sound as when it was built, though deformed at one point by settlement of one of its piers through erosion of the river bed. Rennie’s list of bridges is long. Two more of his -Southwark Bridge and London Bridge - span the River Thames. Below London Bridge, Rennie built the London Docks at Wapping and, with Ralph Walker, the East India Docks farther down the river. With regard to dock equipment, Rennie was ahead of his time. He proposed steam cranes and tramway roads, but both plans were rejected and goods continued to be expensively and laboriously man-handled for long afterwards.
Docks at Hull, Liverpool and many other places were built or designed by Rennie, and much harbour work was undertaken. The building of the breakwater across Plymouth Sound is perhaps the most spectacular of these works.
In the same way as his predecessor, Smeaton, Rennie was responsible for a well-known lighthouse, the Bell Rock, off the Scottish coast between the Firths of Forth and Tay. If his list of completed work is long, his list of reports and schemes is longer. Had some of these projects been carried out, Great Britain would have benefited greatly; but the official mind in those days seems to have been in general singularly timid and lethargic. Perhaps the matter of costs may have appalled it.
A characteristic of the earlier engineers is their intense application to work. Rennie, to his own detriment, was no exception, for it is stated that when he died on October 4, 1821, his unremitting toil had worn him out. A few days before he had been writing to the Navy Board on the subject of dock gates, but no leisured retirement was to round off his activities.
