John Rennie the Elder

John Rennie FRSE FRS (7 June 1761 – 4 October 1821) was a Scottish civil engineer who designed many bridges, canals, and docks.

Rennie, a farmer's younger son, was born at Phantassie, near East Linton, East Lothian, Scotland, and showed a taste for mechanics at a very early age, and was allowed to spend much time in the workshop of Andrew Meikle, millwright, the inventor of the threshing machine, who lived at Houston Mill on the Phantassie estate. After receiving a rudimentary education at the parish school of Prestonkirk Parish Church, he was sent to the burgh school at Dunbar, and in November 1780 he matriculated at the University of Edinburgh, where he remained until 1783. His older brother George remained to assist in the family agricultural business, achieving notability in this arena.

He seems to have employed his vacations in working as a millwright, and so to have established a business on his own account. At this early date the originality of his mind was exhibited by the introduction of cast iron pinions instead of wooden trundles. In 1784 he took a journey south for the purpose of enlarging his knowledge, visiting James Watt at Soho, Staffordshire. Watt offered him an engagement, which he accepted, and after a short stay at Soho he left for London in 1784 to take charge of the works at the Albion Flour Mills, Blackfriars, for which Boulton & Watt were building a steam-engine. The machinery was all designed by Rennie, a distinguishing feature being the use of iron instead of wood for the shafting and framing. About 1791 he started in business as a mechanical engineer on his own account in Holland Street, Blackfriars, whence he and his successors long conducted engineering operations of vast importance. (In the same year, the Albion Flour Mills were destroyed by arson).

...
Wikipedia