RENNIE, John (1761-1821). Civil engineer.Email about this entry
Autograph Letter Signed to an unnamed correspondent, 2 pages 8vo (slight foxing at the head), Stamford Street [Southwark], 9 September 1813. Explaining that he had been away from London and would be unlikely to be able to travel to Ireland that year.
'... since I came to London I find that business of serious importance to the Admiralty will prevent me from going to Ireland this year. ...'
In 1806 Rennie had reported to a commission of civil officers of the navy as to improvements which would have to be made to improve the efficiency of naval dockyards, and the Board of Naval Revision had commissioned him to examine all the royal dockyards. His report in 1807 found almost all of the yards and docks in a deplorable state, largely because of silting and mismanagement. The only place he thought suitable for large scale naval work was Plymouth, where the principal problem was its exposure to southerly gales. His solution to this problems was to build a substantial breakwater, but it was more than five years, largely spent by the commisisoners in arguing over rival schemes, before his plan could be put into effect. The first stone of Rennie's great breakwater was laid on 12 August 1811. His method, then a novel one, was to throw large blocks of stone into the water and to allow the tides to shape them to a suitable base for the finished work. By August 1815, according to Samuel Smiles (Lives of the Engineers, 1862, vol. 2, p. 259) 'not less than 615,057 tons of stone had been deposited, and a length of 1100 yards was raised above low water of spring tides. The complete success of the work was now beyond dispute.' Nevertheless the work was not fully complete until 1848, by which time 3,670,444 tons of rubble and 22,149 cubic yards of masonry had been consumed. The breakwater was said to have been admired by Napoleon when he arrived as a prisoner in Plymouth in 1815.
£325 [No: 25953]
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