Autobiography of Sir John Rennie, F.R.S. 6

Autobiography of Sir John Rennie, F.R.S. 6

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 1_s._ 9_d._ to 2_s._ 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 2_s._ to 1_s._; notwithstanding, however, the prime cost of the

stone, the freight, dressing, mortar, and setting complete in the bridge

cost about 7_s._ 2_d._ to 7_s._ 3_d._, so that the total cost was near

7_s._ 6_d._ 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 565,000_l._, which was 10,000_l._ more

than estimated by Mr. Rennie; the approaches, besides the land and

buildings, cost a further sum of 112,000_l._; so that the total cost of

the bridge and approaches was 677,000_l._, and the land and buildings

and contingencies 373,000_l._, making a total of 1,050,000_l._ 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 4_s._ to 6_s._ a cubic foot in the rough state, timber from 7_l._ to

14_l._ per load, and labour in the same proportion (which is more than

double the present price), we cannot be surprised at the total cost.

 

I still continued my duties at the Southwark Bridge, which was completed

in March, 1819, and was opened without any ceremony by Sir John Jackson,

the chairman of the Company, and the other directors.

 

 

 

 

CHAPTER II.

 

Travels in Switzerland, Italy, Greece, Asia Minor,

Constantinople, and Egypt--Return to England--Death of Mr.

Rennie.

 

 

I had now received a tolerably good education, both theoretical and

practical, as a civil engineer; but before entering fully into practice

on my own account, my father thought it advisable that I should travel

for a time to study what had been done in ancient and modern times both

in architecture and engineering. I accordingly left England on the 7th

of June, 1819, in company with my cousin, Colonel, now General, Sir J.

Aitchison, and the late Lord Hotham, his friend. We had a thirty-three

hours’ passage from Brighton to Dieppe, during which time, having

exhausted the captain’s store of bread and cheese, not very abundant, we

were glad to fall back on a dozen mackerel, which Lord Hotham’s servant

was fortunate enough to catch. We passed through France without much

incident; but when the view from the summit of the Jura suddenly burst

upon us, the magnificent scene made a most lasting impression upon my

memory. The valley of the Rhone, the Lake of Geneva, backed by Mont Blanc

and its splendid range of mountains, rose before us as if by magic; we

were totally unprepared for it, could scarcely believe our senses, and

stood enraptured for nearly half an hour. We then descended to Geneva,

where we passed several days very agreeably, examining what was then the

picturesque old town, with its clumsy, old-fashioned waterworks; for the

improvement of these my father, through the well-known Dr. Marcet, had

just made a design for the municipality, which was much approved of, and

which I understand has since been partially carried into effect. I here

made the acquaintance of General Dufour, so well known for his scientific

acquirements, and after a few days went on an expedition to Chamounix,

where, as no one then thought of ascending Mont Blanc, we climbed the

Montanvert and the Mer de Glace, where I made some experiments with

Leslie’s hygrometer. Having returned to Geneva, we started again on

the 7th July for a more extended tour in the mountains, going by the

lakes of Morat and Bienne, the scene of the great battle of 1476. I

examined these two lakes, which were evidently rapidly filling up, but

by lowering the outfalls a great part of the whole might be recovered,

whereas at present the borders are to a great extent covered with reeds,

and the marshes exhale unwholesome effluvia. After passing through

Freibourg, where the bridge, then newly opened, was considered one of

the wonders of Switzerland, and which, as a most remarkable work of its

kind, I examined attentively, we passed on to Berne, and going through

the mountains, returned to Geneva. On our way, being at Meyringen, and

short of ready cash, we proposed either to return direct to Geneva, or

to change one of Herries’ circular notes; but on offering one of these

notes to the landlord, he at once said there was no occasion for it, as

we were Englishmen, and that was enough. Having produced a large bag of

five-franc pieces, he told us to help ourselves, and was with difficulty

persuaded to take one of Herries’ notes in exchange. I merely mention

this to show how high the name of Englishmen then stood on the Continent.

 

Leaving Geneva for Italy, we proceeded by the route of the Simplon, the

construction of which I had promised to observe very attentively for my

father. The first portion only presents, as objects of interest, the

excavations through the rock of St. Gingough, near the upper end of the

lake. From Martigny we started up the valley of the Rhone, where, though

the ground is generally level, the road yet encounters considerable

difficulties from the river, which here assumes the character of a

torrent, and when swollen by floods sweeps almost everything before it;

wandering from side to side it deposits the _débris_ of the one side

on the banks of the other, forming, we may say, alternately rapids and

almost still pools, which renders it extremely difficult to confine its

course within any reasonable limits; so that the art of the engineer

is taxed to the uttermost. I thought that in many places the works

were not designed with that solidity which is so necessary under such

circumstances, and that sufficient precautions were not taken to arrest

the progress of the _débris_. I considered that by providing depositories

for it at certain favourable stations, the violence of the floods might

have been considerably controlled, a much greater extent of land on

both sides of the river rendered available for cultivation, and the

extensive marshes, which, operated upon by a powerful sun, now produce

most injurious exhalations, might have been deprived of their baneful influence.