In those public works, which come more immediate ly under the profession of a civil engineer, Mr. Rennie had still more experience, and has been equally success ful.
Among the canals, the execution of which lie person ally superintended, have been enumerated the Lancas ter canal, that at Aberdeen, the Grand Western, the Kennet and Avon, the Portsmouth, the Birmingham, and the Woreester,I &c. &c.
Besides the West India docks already described in our account of the Metropolis, (see the article LoNnox, Mr. Rennie is said to have planned the docks at Hull, Greenock, Leith, Liverpool, and Dublin; together with the harbour of Berwick, Dunleary, Holyhead, Ilowth, Newhaven, Queensferry, &c. In addition to these na val works, he planned various important improvements on his Majesty's dock-yards at Portsmouth, Plymouth, Chatham, and Sheerness, and the new naval arsenal at Pembroke was constructed from his designs. He made a design also of a new naval arsenal at North-fleet on the Thames, but the sum of eight millions was consider ed by government as too great a sum to he expended on the undertaking.
The greatest of all Mr. Rennie's naval works, how ever, is undoubtedly the Breakwater at Plymouth, of which we have already given a very full descrip tion § In concluding this list of Mr. Rennie's labours, which has necessarily become a meagre one, in conse quence of our having given accounts of them in other parts of our work, we must not admit his drainage of that tract of marsh lands on the river Trent, Witham, New Welland, &c. and his plan for draining the Bed ford level, which has been partly carried into execu tion.
These various public concerns are said, by one of Mr. licnnie's biographers, to have cost little less than fifty millions sterling, nearly twenty millions of which were spent under his own superintendence. , Although Mr. Rennie was a man of robust figure, and of corresponding strength of constitution, yet, during some of the last years of his life, he had been afflicted with an inflammation of the liver. The dis ease, however, began to assume a more serious form, and finally cut him off, on the 16th of October, 1821, in the 60th year of his age. His remains were interred in St. Pauls, near those of Sir Christopher Wren, and a plain granite slab, with a suitable inscription, was laid upon his tomb.
Mr. Rennie, who married in 1789, and survived his wife, left behind him six children The eldest of these, Mr. George Rennie, has already exhibited very great ta lents in his father's profession, and the second son, John, promises to sustain the reputation of the family.
Mr. Rennie may be justly considered as the first of that school of tre,cical engineers which has been es tablished in Great Britain. No mistake can be greater than to suppose, (as has been generally stated,) that Mr. Rennie was a profound mathematician, or a natural philosopher. Had he been either, he would never have executed those great works which have given re nown to his own name, and to that of his country. When we consider the vast superiority of the French engineers to our own, in theoretical acyaliements, and their inferiority to ours in practical knowledge of every kind, we cannot avoid drawing the eoneltn,ion, that it is from experience alone that those resources of skill and judgement are to be derived which have given preeminence to all the works of British engineers. The experience of foreign countries has shown, that a mere knowledge or pure mathematics is more easily acqoired than that of any branch of science, or of useful know ledge ; and consequently, the possession of it indicates no talent, and no genius of any kind. 1 hose, therefore, who have been early it.itiated into its abstractions, ex perience great difficulty in abandoning the results of theory, and in throwing themselves entirely upon the resources of experiment and observation ; while those who have founded their professional acquirements upon the great practical truths, which are often collected from the of ages, have frequently rejected tl.c aid of theory, even in those cases a here its assist ance might have becn advantageously accepted. Like all extremes, these two arc to be carefully avoided ; but that extreme is to he especially guarded against, which would lead us to renounce those opinions of the value of practical science, which, without naming any living examples, are founded on the history of the lives and labours of Bolton, and Watt, and Rennie.