Autobiography of Sir John Rennie, F.R.S., Past President of the Institute of Civil Engineers / Comprising the history of his professional life, together with reminiscences dating from the commencement of the century to the present time.

by Sir John Rennie

Meanwhile the defective state of drainage of the great level of the fens still continued, and everybody was convinced that the only remedy was to carry into effect the Eau Brink Cut as awarded by Captain Huddart. It was therefore resolved that a new Act of Parliament should be obtained for this purpose, increasing the tax upon the lands proposed to be benefited sufficiently to cover the costs according to the estimate of my father, who was appointed engineer-in-chief of the drainage interests; and the above-mentioned gentlemen, Lord W. Bentinck, Sir A. Hammond, Sir Charles Browne, and Thomas Hoseason, Esq., were appointed as the executive committee.

The Act having passed, Messrs. Jolliffe and Banks tendered for, and received and executed the contract.

The effect of this work greatly exceeded the most sanguine expectations of its supporters. Immediately after it was opened the low-water mark at the upper end of the cut fell five feet, and the drainage waters were carried off with a degree of rapidity which astonished the whole country. The autumn and winter of 1821-2 was characterized by an unusual quantity of rainfall, and if it had not been for the opening of the Eau Brink Cut the whole, or the greater part, of the level of the fens would have been under water, and therefore the fenmen were very well pleased with the result. At this time I was appointed to succeed my father as chief drainage engineer, and the late Mr. Telford had been previously appointed the chief engineer for navigation. Immediately after my appointment, which was in the month of December, 1821, I went to Lynn to examine the works, and was much astonished to find the great effects which had been produced by the Eau Brink Cut. Instead of the circuitous old shallow course, full of shoals and obstructions of every kind, there was a fine straight, deep channel, two miles shorter than the old one, of the proper width, bordered by strong banks of the full height; the floods passed off without difficulty, and the navigation was so much improved that the lighters and barges going up the river from Lynn saved several tides. It is true that upon examining the country between Denver Sluice and Cambridge, there was a great deal of water out in several places, but this was attributed to the interior drains and rivers not being properly defended and embanked, so that they could carry off the water to the main outfall below. I also examined the new steam pumping apparatus, which had lately been erected for draining Soham and other fens. This, although proposed by my father in 1786, was the first of the kind that had been erected. It consisted of a scoop wheel, with a perpendicular lift, worked by a condensing engine. It answered its object completely, and has since been imitated by numerous others with equal success in different parts of the fen and lowland districts. Yet in many places it has been found very difficult to induce the fen proprietors to combine together in order to effect a natural drainage, which would be better and less expensive; they prefer to act independently of each other, and adopt the steam wheel. Still, even with this, the main outfalls must be improved to their fullest extent, otherwise the water cannot run off; and when the floods in the adjacent rivers rise so high that the banks are endangered, the pumping must be discontinued, otherwise the banks will break, and then a greater injury will ensue. Nevertheless, the steam pumping apparatus is an immense improvement on the old windmill, which could only work when there was wind.

My next appointment was to succeed my father as engineer-in-chief to Ramsgate Harbour.

This harbour was established by special Act of Parliament for the purpose of affording shelter to vessels of 300 tons lying in the Downs during south-west gales. When these winds prevail that anchorage is crowded with all classes of vessels, and the smaller ones, not being so well found with ground tackle as the larger, are liable to be driven from their moorings and fall foul of the larger vessels, causing them to go adrift also, and thus creating considerable confusion and damage; but by having Ramsgate under their lee, the small vessels can always get under way, run for it at the commencement of the flood, and reach it in safety long before high water, at which time the Goodwin Sands are covered, and a heavy sea rolls into the Downs. In fact, Ramsgate Harbour was made for clearing the Downs of small vessels, so that the large ones may ride in safety, and so far has effectually answered its object.

There were a certain number of trustees appointed under the Act, who were selected from the principal merchants and shipowners of London, and the Deputy Master and three or four Elder Brethren of the Trinity were members of the Board of Trustees ex officio. At the time I was appointed engineer, the celebrated Sir William Curtis, Bart., member for the City of London, was chairman, and the worthy Deputy Master of the Trinity House, Sir John Woolmore, represented that Corporation with three others of the Elder Brethren. As this was one of the oldest and most important harbour trusts in the kingdom, I felt great honour in being appointed their chief engineer, the more so as the celebrated Smeaton and my father had previously occupied that position. It was here that Smeaton followed out the idea that had been originally proposed at Dundee, of establishing an inner basin with sluices for the purpose of scouring away the mud which continually accumulated in the outer harbour, owing to the great quantity of alluvial matter brought in from the adjacent coast and waters, which otherwise in a very short time would have filled it up and rendered it useless. Ramsgate Harbour was also celebrated for being the first place of the kind where the diving bell was introduced by Smeaton for the purpose of laying down moorings and removing obstacles under water. The diving bell was afterwards, in 1813, much improved, and rendered, for the first time, applicable to building masonry under water with as much security and accuracy as building upon dry land. In such an exposed situation it was more economical and expeditious than the old cofferdams; it was in this manner Mr. Rennie rebuilt the east pier-head in 17 feet at low-water spring tides, which was originally made by Smeaton, and which failed. I also succeeded my father at Sunderland, Donaghadee, Port Patrick, and Kingstown harbours, the West India Docks, besides other places soon afterwards, so that I had a large business, and was daily getting more.

The most difficult and anxious work, however, at that time was the new dockyard at Sheerness, designed and partly carried into effect by my father. He originally, in the year 1807, recommended that the old dockyard, which was composed only of some old wooden slips imbedded in the mud, a few storehouses, a wretched basin, lined with wooden walls, and some timber jetties, should be abolished. He said that it was on the lee or wrong side of the harbour, that the foundation for new works was of mud and quicksand, that the space, on account of the buildings in the old town, was very confined, and, therefore, that to make a good dockyard there would be very expensive, and he thought it would be far better to make a new complete establishment at Northfleet, just above Gravesend, and to get rid of Woolwich, Deptford, and Sheerness altogether. Mr. Pitt, then Prime Minister, decided that it should be done; but when he died the matter fell to the ground, as I have before said, although the land was bought for the purpose.

However, after the great war had terminated, in 1815, the nation was naturally anxious to reduce the expenditure as much as possible, so that the House of Commons would not listen to the idea of expending any large sums upon great new works either for the navy or the army; and it was only after considerable difficulty that the House of Commons would grant money for the repairs of Sheerness Dockyard, and, like most extensive repairs, it was found, when too late, that it would have been far better to have abandoned Sheerness altogether.

Nevertheless it was absolutely necessary to do something to the Thames and Medway dockyards, to keep in repair the large fleet of vessels which was there laid up in ordinary. The total number of pennants flying at the close of the war was about 1000, and the last vote for seamen in 1815 included 127,000 sailors and marines. As there was greater depth of water at Sheerness than at any of the dockyards, and as the harbour immediately contiguous was capable of accommodating with ease any number of large vessels, Sheerness was decided upon as the place where the greatest repairs and improvements should be made, and it ended in an entirely new dockyard being built. The works accordingly commenced in 1815, and the late Lord Melville laid the first stone at the north end that year. It ended in expending nearly 3,000,000l., 1,700,000l. of which went to the engineering department, and the remainder in the purchase of ground, buildings in the town of Sheerness, in storehouses, mast and timber ponds, smithery, admiral’s and officers’ houses. The engineering works were of the most difficult kind; the foundations were composed of nothing but soft mud and loose quicksands to an almost interminable depth, so that my father was obliged to invent an entirely new system of hollow walls faced with granite in front and brick behind. This system of walls, which was entirely new, by giving a greater superficial area of bearing surface with the same weight of materials, rendered them thoroughly secure. He had adopted this kind of construction with perfect success at the docks at Great Grimsby, in Lincolnshire, and they succeeded equally well at Sheerness, although exposed to much greater difficulties. The dockyard as completed consists of one basin of nearly 3 acres, at the east end of which are three docks for first-rate vessels of war, with a depth of 9 feet at low water of spring tides, the basin being of the same depth, so that with a rise of tide of 18 feet at spring tides the largest vessels can always be docked at those times. There is also another tidal basin of about the same size, together with large storehouses, smithery, mast ponds, boathouses, admiral’s and officers’ houses, chapel, &c., and ample space for timber and other materials. This dockyard, therefore, as was the intention, is well adapted for keeping in repair the numerous vessels lying up in ordinary in the adjacent harbour, or for executing any repairs which vessels on the northern stations may require; it never was intended to be a building yard, and it answers its original purpose well. It should be mentioned, that here Mr. Rennie first introduced cast-iron gates for the dry docks; these fitted to the granite quoins so nicely by polishing the two surfaces, iron and stone, with emery, that they worked together perfectly, and were completely water-tight; and although they have now been in use forty-five years, they are as good as on the day when they were made.

At the time that these works were proceeding, it was decided to make a new large granite dry dock at Chatham, similar to those at Sheerness; and some improvements in the line of river wall, which partly interfered with the free circulation of the tide there, were being constructed when I was appointed, and I finished them.