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

We reached Bruges about noon, and had just time to examine the fine cathedral and townhall, as well as the interesting town, its quaint old buildings, quays, mercantile warehouses, all in the architecture of the Middle Ages, during which Bruges attained its greatest prosperity. We left this interesting town in the afternoon by another trackschuyt for Ostend, about 12 miles distant, by a canal of the same dimensions as the one above described. Most of these canals being connected with each other, Brussels, Ghent, Malines, Louvain, and the other large towns, possessed a complete network of water communication with the ports of Antwerp and Ostend, and trade is carried on with the greatest facility.

We reached Ostend in the evening, and learned that a packet was about to sail for Margate, of which we determined to avail ourselves. We had, however, sufficient time to examine this indifferent port, the second in the kingdom, which, in addition to a badly-contrived entrance by two guide piers, has two small docks. It is a mere tidal harbour, with an awkward bar at the entrance, and numerous shoals on the outside. The town possesses nothing remarkable; it was then garrisoned by English troops, and there was constant communication with England.

From this period I devoted my time almost exclusively to the Waterloo and Southwark bridges, but particularly to the latter, which was almost entirely under my direction, subject to the orders of my father. Besides the above works, I was a good deal employed in the drawing office in making drawings and estimates and calculations for a variety of new works upon which my father was engaged. I also occasionally visited the rolling and other machinery of the Royal Mint on Tower Hill, which my father at that time was constructing for the Government, and during the evenings I was employed in learning mathematics under Dr. Bradley and Dr. Firminger, and the Italian, French, and German languages, so that my time from morning to evening was fully employed. I must not omit to say that at this time I attended the lectures of the celebrated Sir Humphry Davy, the Professor of Chemistry at the Royal Institution, who at that day astonished the world by his wonderful discoveries.

The first, second, and third arches of the Waterloo Bridge being completed, Mr. Rennie determined to slacken the centres of the first arch, which was on the Surrey shore, where the bridge commenced. This was when the arches were entirely relieved from the centres, and the total subsiding of this arch was 2½ inches, which is nearly half an inch less than had been allowed; the centres were then removed from the first arch to the fourth arch, only three centres being employed. Each centre consisted of eight ribs, upon the truss principle, resting upon a compound system of wedges, supported upon struts placed upon the offsets of the piers and abutments; all the ribs were well connected together by transverse and diagonal ties, as well as the planking upon which the arch-stones rested. The trestles or bearers of the centre ribs, together with the wedges, having been first fixed in their places upon the offsets of the pier and abutment where the centre was to be fixed, four ribs of the centre were transferred, and fixed upon them in the following manner.

The ribs of the centre having been constructed upon a platform upon the shore near the bridge, a large barge or floating stage, capable of carrying four complete ribs, which weighed 40 tons each, was built to receive them. This floating stage was extremely strong, and transversely across the centre of it there were four strong stages at the same distance from each other as the ribs of the centre were intended to be when fixed in their position, to support the arches whilst building. These stages were supported by double transverse beams, resting upon powerful screws 15 inches diameter, in boxes resting upon the bottom of the vessel. Above each of these stages, yet securely attached to them, was a framework, to which the ribs of the centres were lashed whilst being transported to their places. When the centre ribs were finished and all was ready, the floating stage, at high water, was brought alongside the platform, upon which the ribs of the centre had been constructed, and were lying ready to be transferred to their places. Each rib was then raised by means of powerful sheer-poles, to which were double-purchase crabs, treble blocks, with all the necessary ropes, chains, and other tackle, by which means each rib of the centre was readily raised from the platform where it was built and transferred to its proper stage in the floating barge, and there secured in an upright position, when the ribs had been fixed in their places. The barge was then floated into the opening where the arch was to be constructed, which was generally done about half an hour before high water, so as to allow ample time to adjust and fix the ribs over the corresponding pair of wedges and trestles upon which it was ultimately to rest, which was done as the tide fell, and adjusted to the greatest nicety by the screws before mentioned; when the rib had been fixed in its place, the barge returned to bring another, which was served in the same manner as the first, and thus the fixing of one centre occupied only six days. This system answered most effectually, and was subsequently adopted by Mr. Robert Stephenson for fixing the great tubes for the Menai and Conway bridges.

The Waterloo Bridge, as well known, consists of nine equal semi-elliptical arches, 120 feet span each, with a rise of 34 feet 6 inches, the keystones at the crown being 4 feet 6 inches deep and 10 feet at the spring, and 18 inches thick at the soffit; inverted arches on each pier between the main arches 4 feet 6 inches deep. The piers were 20 feet wide, each having projecting buttresses, supported by two three-quarter Doric columnar pilasters, over each pier, the whole being surmounted by a Doric block cornice and balustrade parapet, level from end to end, the same as the roadway. The roadway above the piers was supported by six brick walls, 2 ft. 3 in. thick, covered with corbel stones. The shores being low on both sides of the river, the approaches are constructed so as to form an inclined plane rising 1 in 30 on the Surrey side, and nearly level on the north, or Middlesex side, with the Strand, upon a series of brick arches 16 feet wide each. These arches serve for storehouses. The roadway was formed by a layer of well-puddled clay 15 inches thick, then a layer of lime and of fine gravel 3 inches thick, then a layer of equally broken granite, in pieces 2 inches in diameter, 1 foot thick. Through the centre of the masonry of each pier a hole 18 inches in diameter was cut, entering the river on one side of the pier at low water, and from the top of this hole inside the pier cast-iron branch pipes of the same diameter were carried to side drains on each side of the roadway, so that all rain and surface water was effectually carried off into the river, thus preventing leakage.

The piers and abutments were founded in the solid bed of the river, which is strong gravel; they rest upon a wooden platform, supported upon piles 12 inches in diameter driven 20 feet into the bed of the river. The whole of the arches and exterior face of the bridge are built of Cornish granite, from the vicinity of Penryn, and the balustrade is made of fine grey Aberdeen granite.

The contract for the Cornish granite was taken by a very worthy man of the name of Gray, and the price was such as on so large a quantity ought to have enabled him to realize a very handsome profit; but he had no system or machinery adequate for the purpose, and instead of opening quarries properly upon an enlarged scale in the solid rock, by which he would have saved a great deal, he chiefly confined his operations to the loose outlying blocks, which reduced his profits considerably, and in the end it is very doubtful whether he did more than cover his expenses. As the dressing of granite for masonry was entirely new at that time, nothing having been built of this material in London, it was extremely difficult to find masons who would undertake it, even at such enormous prices as 1s. 9d. to 2s. per cube foot, so that the contractors, Messrs. Jolliffe and Banks, could not afford to pay it. Workmen were therefore obtained from Aberdeen, and the price was ultimately reduced from 2s. to 1s.; notwithstanding, however, the prime cost of the stone, the freight, dressing, mortar, and setting complete in the bridge cost about 7s. 2d. to 7s. 3d., so that the total cost was near 7s. 6d. It should be observed, however, that at that time there was a duty of threepence per cubic foot (or ton?) on stone, which has since been taken off. The interior stone consisted of hard sandstone from Derbyshire and Yorkshire.

The bridge and approaches were completed and opened with great ceremony by George IV., then Prince Regent, on the 15th of June, 1817, in commemoration of the battle of Waterloo, after which it was especially named. Twenty-five pieces of artillery were placed on the centre of the bridge, which fired a salute as His Royal Highness, the directors of the Company, and a brilliant suite walked over in procession, when he christened it Waterloo Bridge, and declared it open to the public. His Royal Highness came by water in his state barge, accompanied by the Admiralty and other barges, in which were the ministers and suite; he landed at the stairs on the south-east side of the bridge, and walked over it from south to north; he embarked again on the north-east side, and returned to Whitehall and Carlton House. The sight was very brilliant, the weather magnificent, and everybody seemed to be satisfied.

The total cost of the bridge was 565,000l., which was 10,000l. more than estimated by Mr. Rennie; the approaches, besides the land and buildings, cost a further sum of 112,000l.; so that the total cost of the bridge and approaches was 677,000l., and the land and buildings and contingencies 373,000l., making a total of 1,050,000l. This is certainly a very large sum for a bridge and its approaches; but when its extent is considered, the bridge alone being a quarter of a mile long, and the approaches nearly three-quarters of a mile more, also the great cost of materials and labour of every kind, the stone-cutting costing from 4s. to 6s. a cubic foot in the rough state, timber from 7l. to 14l. per load, and labour in the same proportion (which is more than double the present price), we cannot be surprised at the total cost.