Smeaton & Rennie V.
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CHAPTER V.

MR. RENNIE'S DRAINAGE OF THE LINCOLN AND
CAMBRIDGE FENS.



NOTWITHSTANDING all that had been done for the drainage of the Fens, as described in the early part of this work, large districts of reclaimable lands in Lincoln still lay waste and unprofitable.  As early as 1789, Mr. Rennie's attention was drawn to the drowned state of the rich low-lying lands to the south of Ely.  He then recommended the application of Watt's steam-engine to pump the water out of the Botteshaw and Soham Fens, which contained about five thousand acres of what was commonly called "rotten land."  But the Fen men would not have the steam-engine.  They were too much prejudiced in favour of drainage by windmills, as practised in Holland.  It was not until many years after, that his recommendation was adopted and the steam-engine was employed to pump the water from the low-lying swamps which could not otherwise be cleared.  The results were so successful, that the same agency became generally employed for the purpose, not only in England but in Holland itself, where the forty-five thousand acres of Haarlemer Meer have since been effectually drained by the application of the steam-engine.

 

Wildmoor Fen; a classic Lincolnshire fenland view.
© Copyright Richard Croft and licensed for reuse under this Creative Commons Licence.


    One of the most important works of thorough drainage carried out by Mr. Rennie, was in that extensive district of South Lincolnshire which extends along the south verge of the Wolds, from near the city of Lincoln eastward to the sea.  It included Wildmore Fen, West Fen, and East Fen, and comprised about seventy-five thousand acres of land which lay under water for the greater part of each year, and was thus comparatively useless either for grazing or tillage.  The only crop grown in the fens was tall reeds, which were used as thatch for houses and barns, and even for churches.

    The river Witham, which flows by Lincoln, had been grievously neglected and allowed to become silted up,—its bottom being in many places considerably above the level of the land on either side.  Hence, bursting of the banks frequently occurred during floods, causing extensive inundation of the lower levels,—only a small proportion of the floodwaters being able to force their way to the sea.

 

Blankney Fen: Blankney Drove looking northeast.
© Copyright Ian Carrington and licensed for reuse under this Creative Commons Licence.


    The wretched state of the land may be inferred from the fact that, about seventy years since, a thousand acres in Blankney Fen, constituting part of "the Dales,"—now one of the most fertile parts of the district between Lincoln and Tattershall were let annually by public auction at Horncastle, and the reserved bid was only £10 for the entire area! [p.285]  It is stated that, about the middle of last century, there were not two houses in the whole parish of Dogdyke communicable with each other during the winter, except by boat; this being also the only means by which the Fen-slodgers could get to church.  Hall, the Fen Poet, speaks of South Kyme, where he was born, as a district in which, during the winter season, nothing was to be seen—


"But naked flood for miles and miles."


The entire breadth of Lincolnshire north of Boston often lay under water for months together:—


"'Twixt Frith bank and the wold side bound,
  I question one dry inch of ground.
  From Lincoln all the way to Bourne,
  Had all the tops of banks been one,
  I really think they all would not
  Have made a twenty acre spot."


Until as recent a date as forty years back, the rich and fertile district of Waldersea, about eight thousand acres in extent, was, as its name imports, a sea in winter.  Well might Roger Wildrake describe his paternal estate of "Squattlesea Mere" as being in the "moist county of Lincoln!"

    Arthur Young visited this district in 1793, and found the freeholders of the high lands adjoining Wildmore and West Fens depasturing their sheep on the drier parts during the summer months; but large numbers of them were dying of the rot.  "Nor is this," he adds, "the only evil; for the number stolen is incredible.  They are taken off by whole flocks, as so wild a country (whole acres being covered with thistles and nettles four feet high and more) nurses up a race of people as wild as the fen."  The few wretched inhabitants who contrived to live in the neighbourhood for the most part sheltered themselves in huts of rushes or lived in boats.  They were constantly liable to be driven out of their cabins by the waters in winter, if they contrived to survive the attacks of the ague to which they were perennially subject. [p.287]

    The East Fen was the worst of all.  It was formerly a most desolate region, though it now presents probably the richest grazing land in the kingdom.  Being on a lower level than the West and Wildmore Fens, and the natural course of the waters to the sea being through it to Wainfleet Haven, it was in a much more drowned state than those to the westward.  About two thousand acres were constantly under water, summer and winter.  One portion of it was called Mossberry or Cranberry Fen, from the immense quantities of cranberries it produced.  A great part of the remainder of the East Fen consisted of shaking bog, so treacherous and so deep in many places that only a desperate huntsman would venture to follow the fox when he took to it, and then he must needs be well acquainted with the ground.

    Matters were in this state when Sir Joseph Banks, then President of the Royal Society, endeavoured to stir up the landowners to undertake the drainage of the district.  He was the proprietor of a good estate at Revesby, near Tattershall; and his mansion of Abbot's Lodge, standing on an elevated spot, overlooked the East and West Fens, of which it commanded an extensive view.  Sir Joseph spent a portion of every year at Revesby, as he did at his other mansions, leaving each at special times appointed beforehand, almost with the regularity of clockwork.  He was a popular and well-known man, jolly and good-humoured, full of public spirit, and, though a philosopher, not above taking part in the sports and festivities of the neighbourhood in which he resided.  While Sir Joseph lived at Revesby he used to keep almost open house, and a constant succession of visitors came and went—some on pleasure, some on friendship, and some on business.

    The profuse hospitality of the place was enjoyed not less by the postilions and grooms who drove thither the baronet's guests, than by the visitors themselves; and it was esteemed by the hotel postboys a great privilege to drive a customer to Revesby.  On one occasion, when Mr. Rennie went to dine and sleep at the Lodge, he took an opportunity of saying to the principal butler that he hoped he would see to his postboy being kept sober, as he wished to leave before breakfast on the following morning.  The butler replied, with great gravity, that he was sorry he could not oblige Mr. Rennie, as the same man had left Revesby sober the last time he was there, but only on condition that he might be allowed to get drunk the next time he came.  "Therefore," said the butler, "for the honour of the house, I must keep my word; but I will take care that you are not delayed for the want of horses and a postboy."  The butler was as good as his word: the man got drunk, the honour of Revesby was saved, and Mr. Rennie was enabled to set off in due time next morning.

 

Sir Joseph Banks, Bt, KCB, FRS (1743-1820), English botanist and
patron of science. From a painting by Thomas Phillips (1770-1845)
 Picture Wikimedia Commons.


    From an early period Sir Joseph Banks entertained the design of carrying out the drainage of the extensive fen lands lying spread out beneath his hall window, and making them, if possible, a source of profit to the owners, as well as of greater comfort and better subsistence for the population.  Indeed, the reclamation of these unhealthy wastes became quite a hobby with him; and when he could lay hold of any agricultural improver, he would not let him go until he had dragged him through the Fens, exhibited what they were, and demonstrated what fertile lands they might be made.  When Arthur Young visited Revesby about 1799, Sir Joseph immediately started his favourite topic.  "He had the goodness," says Young, in his Report on Lincolnshire, "to order a boat, and accompanied me into the heart of East Fen, which had the appearance of a chain of lakes, bordered by great crops of reed."

    Sir Joseph was a man of great public spirit and determination: he did not allow the matter to sleep, but proceeded to organise the ways and means of carrying his design into effect.  His county neighbours were very slow to act, but they gradually became infected by his example, and his irresistible energy carried them along with him.  The first step taken was to call meetings of the proprietors in the several districts adjoining the drowned and "rotten lands."  Those of Wildmore Fen met at Horncastle on the 27th of August, 1799, and resolutions were adopted authorising the employment of Mr. Rennie to investigate the subject and report to a future meeting.

    One reason, amongst others, which weighed with Sir Joseph Banks in pressing on the measure was the scarcity of corn, which about that time had risen almost to a famine price.  There was also great difficulty in obtaining supplies from abroad, in consequence of the war which was then raging.  Sir Joseph entertained the patriotic opinion that the best way of providing for the exigency was to extend the area of our English food-ground by the reclamation of the waste lands; and hence his determination to place under tillage, if possible, the thousands of acres of rich soil, equal to the area of some English counties, lying under water almost at his own door.  A few years' zealous efforts, aided by the skill of the engineer, produced such results as amply to justify his anticipations, and proved his judgment to be as wise as his patriotism was beneficent.

    The manner in which Mr. Rennie proceeded to work out the problem presented to him, was thoroughly characteristic of the man.  Most of the drainage attempted before his time was of a very partial and inefficient character.  It was enough if the drainers got rid of the surplus water anyhow, either by turning it into the nearest river, or sending it in upon a neighbour.  What was done in one season was usually undone in the next.  The ordinary drainer did not care to look beyond the land immediately under his own eyes.  Mr. Rennie's practice, on the contrary, was founded on a large and comprehensive view of the subject.  He was not bounded by the range of his vision, but took into account the whole contour of the country.  He had to consider the rainfall of the districts through which his drains were to run, as well as that of the central counties of England, whose waters flowed down upon the Fens; the requirements of the lands themselves as regarded their irrigation and navigation; and, finally, the most effectual method not only of removing the waters from particular parts, but of providing for their effectual discharge by proper outfalls into the sea.

    What was the problem now to be solved by our engineer?  It was how best to carry out to sea-the surplus waters of a district extending from the eastern coast to almost the centre of England.  Various streams descending from the Lincolnshire wolds flowed through the level, whilst the Witham brought down the rainfall not only of the districts to the north and east of Lincoln, but of a large part of the central counties of Rutland and Leicester.  It was, therefore, necessary to provide for the clear passage of these waters, and also to get rid of the drainage of the Fens themselves, a considerable extent of which lay beneath the level of the sea at high water.

    It early occurred to Mr. Rennie that, as the waters of the interior for the most part came from a higher level, their discharge might be provided for by means of distinct drains, and prevented from at all mingling with those of the lower lying lands.  But would it be possible to "catch" these highland waters before their descent upon the Fens, and then to carry them out to sea by means of independent channels?  He thought it would; and with this leading idea in his mind he proceeded to design his plan of a great "catch-water drain," extending along the southern edge of the Lincolnshire wolds.

    But there were also the waters of the Fens themselves to be got rid of, and how was this to be accomplished?  To ascertain the actual levels of the drowned lands, and the depth to which it would be necessary to carry the outfall of his drains into the sea, he made two surveys of the district—the first in October 1799, and the second in March 1800 thus observing the actual condition of the lands both before and after the winter's rains.  At the same time he took levels down to the sea out-falls of the existing drains and rivers.  He observed that the Wash, into which the Fen waters ran, was shallow and full of shifting sands and silt.  He saw that, during winter, the rivers were loaded with alluvial matter held in suspension, and that, at a certain distance from their mouths, the force of the inland fresh and the tidal sea-waters neutralised each other; and that there a sort of stagnant point was formed, at which the alluvium was no longer held in suspense by the force of the current.  Hence it became precipitated in the channels of the rivers, and formed banks or bars in the Wash outside their mouths, which proved alike obstructive to drainage and navigation.

    It required but little examination to detect the utter inadequacy of the existing outfalls to admit of the discharge of the surplus waters of so extensive a district.  The few sluices which had been provided had been badly designed and imperfectly constructed.  The levels of the outfalls were too high, and the gowts and sluices too narrow, to accommodate the drainage in flood-times.  These outfalls were also liable, in dry summers, to become choked up by the silt settling in the Washes; and when a heavy rain fell, down came the waters from the highlands of the interior, and, unable to find an outlet, they burst the defensive banks of the rivers, and an amount of mischief was thus done which the drainage of all the succeeding summer failed to repair.

    Accordingly, the next essential part of Mr. Rennie's scheme was the provision of more effectual outfalls; with which object he designed that they should be cut down to the lowest possible level of low water, whilst he arranged that at the points of outlet they should be mounted with strong sluices, opening outwards; so that, whilst the fresh waters should be allowed freely to escape, the sea should be valved back and prevented flowing in upon the land.  The third and last point was to provide for the drainage of the Fen districts themselves by means of proper cuts and conduits for the voidance of the Fen waters.

    Such were the general conclusions formed by Mr. Rennie after a careful consideration of the circumstances of the case, which he embodied in his report to the Wildmore Fen Proprietors [p.294] as the result of his investigations.  The two great features of his plan, it will be observed, were: (1) his intercepting or catchwater drains, and (2) his cutting down the outfalls to lower levels than had ever before been proposed.  Simple though his system appears, now that its efficacy has been so amply proved by experience, it was regarded at the time as a valuable discovery in the practice of fen-draining, and indeed it was nothing less.

    There were, however, plenty of detractors, who alleged that it was nothing of the kind.  Any boy, they said, who has played at dirt-pies in a gutter, knows that if you make an opening sufficiently low to let the whole contained water escape, it will flow away.  It was the story of Columbus and the egg over again.  It was quite true; and yet no one had ever proposed or attempted Rennie's plan; and it cost him many years of arguing, illustration, and enforcement, before he could induce the Fen-drainers of other districts to adopt the same simple but thoroughly scientific method by which he had effectually drained the Lincolnshire Fens.  And even to this day there are whole districts in which the stubborn obstinacy of ignorant obstructives still continues to stand in the way of its introduction.  The Wildmore Fen proprietors, however, had the advantage of being led by a sagacious, clear-seeing man in Sir Joseph Banks, who cordially supported the adoption of the plan with all the weight of his influence, and Mr. Rennie was eventually empowered to carry it into execution.

 

Anton's Gowt, Lincolnshire.
© Copyright Richard Croft and licensed for reuse under this Creative Commons Licence.


    In laying out the works, he divided them according to their levels, placing Wildmore and West Fen in one plan, and East Fen in another.  In draining the former, the outlet was made by Anton's Gowt, about two miles and a half above Boston, and by Maud Foster, a little below that town.  But both of these, being found too narrow and shallow, were considerably enlarged and deepened, and provided with double sluices and lifting gates: one set pointing towards the Witham, in order to keep out the tides and river floods; the other to the land, in order to prevent the water in summer from draining too low, and thereby hindering navigation as well as the due irrigation of the lands.  An extensive main drain was also cut through the Wildmore and West Fens to the river Witham, about twenty-one miles long and from eighteen to thirty feet wide, the bottom being an inclined plane falling six inches in the mile.

    The level of the East Fen being considerably lower than that of the Fens to the westward, it was necessary to provide for its separate drainage, but on precisely the same principles.  From the levels which were taken, it appeared that the bottom of "the Deeps," which formed part of the East Fen, was only two feet six inches above the cill of Maud Foster Sluice, thirteen miles distant; whereas its highest parts were but eight feet above the same point, giving a fall of only an inch and eight-tenths per mile at low water of neap tides.  From some of the more distant parts of the same Fen, sixteen miles from the outfall, there would only have been a fall of five-tenths of an inch per mile at low water.  It was clear, therefore, that even the higher levels of the East Fen could not be effectually drained by the outfall at Anton's Gowt or Maud Foster; and hence arose the necessity for cutting an entirely separate main drain, with an outfall at a point in the Wash outside the mouth of the river Witham. [p.296-1]

 

Hobhole Drain, looking north from Ings Bridge near Hilldyke, Lincolnshire. [p.296-2]
© Copyright Richard Croft and licensed for reuse under this Creative Commons Licence.


    This east main cut, called the Hobhole Drain, is about eighteen miles long and forty feet wide, diminishing in breadth according to its distance from the outfall; the bottom being an inclined plane falling four inches in the mile towards the sluice at Hobhole in the Wash.  This drain is an immense work, defended by broad and lofty embankments extending inland from its mouth, to prevent the contained waters flooding the surrounding lands.  It is protected at its sea outlet by a strong sluice, consisting of three openings of fifteen feet each.  When the tide rises, the gates, acting like a valve, are forced back and hermetically closed; and when it falls, the drainage waters, which have in the mean time accumulated, force open the gates again, and the waters flow into the sea down to the level of low water. A connection was also formed between the main drains emptying themselves at Maud Foster (three miles higher up the Witham) and the Hobhole Drain, the flow being regulated by a gauge; so that, during heavy floods, not only the low land waters of the East Fen districts were effectually discharged at Hobhole, but also a considerable portion of the drainage of the West and Wildmore Fens.

    An essential part of the scheme was the cutting of the catchwater drains, which were carried quite round the base of the high lands skirting the Fens; beginning with a six-feet bottom, and widening out towards their embouchures to sixteen feet.  The principal work of this kind commenced near Stickney, and was carried eastward towards Wainfleet, to near the Steepings river.  It was connected at Cowbridge with the main Hobhole Drain, into which the highland waters brought down by the catchwater drain were thus carried, without having been allowed, until reaching that point, to mix with the Fen drainage at all.

    It would be tedious to describe the works more in detail; and perhaps the outline we have given, aided by the maps of the district, will enable the reader to understand the leading features of Mr. Rennie's comprehensive design.  The works were necessarily of a very formidable character, the extent of the main and arterial drains cut during the seven or eight years they were under execution being upwards of a hundred miles.  They often dragged for want of funds, and encountered considerable opposition in their progress; though the wisdom of the project was in all respects amply justified by the result. [p.297]

    When the drainage of Wildmore and West Fens was finished, forty thousand acres of valuable land were completely reclaimed, and in a few years yielded heavy crops of grain.  East Fen was attacked the last, the difficulties presented by its formidable chain of lakes being by much the greatest; but the prize also was by far the richest.  When the East Fen waters were drained off, the loose black mud settled down into fertile soil.  Boats, fish, and wild-fowl disappeared, and the plough took their place.  After being pared and burnt, the land in the East Fen yielded two and even three crops of oats in succession, of not less than ten quarters to the acre.

    The cost of executing the drainage had no doubt been very great, amounting to about £580,000 in all, inclusive of expenditure on roads, &c.; against which had to be set the value of the lands reclaimed.  In 1814 Mr. Anthony Bower, surveyor and valuer, estimated their improved rental at £110,561; and allowing five per cent. on the capital expended on the works, we thus find the increased net value of the drained lands to be not less than £81,000 per annum, which, at thirty years' purchase, gives a total increased value of nearly two millions and a half sterling! [p.299]

    It was a matter of great regret to Mr. Rennie that his design was not carried out as respected the improved outfall of the Witham.  It was an important part of his original plan that a new and direct channel should be cut for this river from Boston down to deep water at Clayhole, where the tide ebbed out to the main sea level, and there was little probability of the depth being materially interfered with by silting for many years to come.  This new channel would have enabled all the waters—lowland as well as highland—to be discharged into the sea with the greatest ease and certainty.  It would also have completely restored the navigation of the river, which had become almost entirely lost through the silting up of its old winding channel.

    But the River Witham was under the jurisdiction of the corporation of Boston, who were staggered by the estimated cost of executing the proposed works, though it amounted to only £50,000.  Accordingly, nothing was done to carry out this part of the design, and the channel continued to get gradually worse, until at length it was scarcely possible even for small coasters to reach Boston Quay.  As late as the year 1826 the water was so low that little boys were accustomed to amuse themselves by wading across the river below the town even at high water of neap tides.  The corporation were at last compelled to bestir themselves to remedy this deplorable state of affairs, and they called in Sir John Rennie to advise them in their emergency.  The result was, that as much of the original plan of 1800 [p.300] was carried out as the state of their funds would permit: the lower part of the channel was straightened, and the result was precisely that which the engineer had more than thirty years before anticipated.  The tide returned to the town, the shoals were removed, and vessels drawing from twelve to fourteen feet water could again come up to Boston Quay at spring tides.

    Mr. Rennie was equally successful in carrying out drainage works in other parts of the Fens, on the same simple but comprehensive principles. [p.301]  He thus drained the lowlands of Great Steeping, Thorpe, Wainfleet All Saints, Forsby, and the districts thereabout, converting the Steepings river into a catchwater drain, and effectually reclaiming a large acreage of highly valuable land.  He was also consulted as to the better drainage of the North Level, the Middle Level, South Holland, and the Great Bedford Level; and his valuable reports on these subjects, though not carried out at the time, for want of means, or of public spirit on the part of the landowners, laid the foundations of a course of improvement which has gone on until the present day.  It is much to be regretted that his plan of 1810, for the drainage of the Great Level, by means of more effectual outfalls and a system of intercepting catchwater drains, was not carried out; for there is every reason to believe that it would have proved as completely successful as his drainage of the Fens of Lincolnshire.  The only part of his scheme that was executed was the Eau Brink Cut, for the purpose of securing a more effectual outfall of the river Ouse into the Wash near King's Lynn.

    The necessity for this work will be more clearly understood when we explain the circumstances under which its construction was recommended.  It will be observed from the map of the Fen district (vol. i. p.37), that the river Ouse flows into the shallows of the Wash near the town of King's Lynn, where it is charged with the waters of the Great Bedford Level as well as of Huntingdon, Bedford, and Cambridge, and of the highlands of the western parts of Norfolk and Suffolk.  Immediately above Lynn, the old river made an extensive bend of about five miles in extent, to a point called German's Bridge.  This channel was of very irregular breadth, and full of great sand beds which were constantly shifting.  In some places it was as much as a mile in width, and divided into small streams, which varied according as the tidal or the fresh waters were, for the time being, most powerful.  During floods, the flow of the river was so much obstructed that the waters could not possibly get away out to sea during the ebb, so that at the next rise of the tide they were forced back into the interior, and thus caused serious inundations in the surrounding country.

    Much good land which had formerly been productive, had become greatly deteriorated, or was apparently lost for agricultural purposes.  Some districts were so constantly flooded, and others were so wet, that they were rapidly returning to their original state of reeds and sedge.  In the neighbourhood of Downham Eau, the harvest-men were, in certain seasons, obliged to stand upon a platform to reap their corn, which was carried to and from the drier parts in boats; and some of the farmers, in like manner rowed through their orchards in order to gather the fruit from the trees.  A large portion of Littleport Fen, in the South Level, was let at a shilling an acre, and, in the summer-time, cattle were turned in amongst the reed and "turf-bass," and were not seen again for weeks.  In Marshland Fen, the soil was so soft that wooden shoes, or flat boards, were nailed on the horses' feet over the iron ones, to prevent them from sinking into the soil.

    The fresh waters were in this way penned up within the land to the extent of about seven feet; and over an extensive plain, such as the Bedford Level, where a few inches of fall makes all the difference between land drained and land drowned, it is clear how seriously this obstruction of the Ouse outfall must have perilled the agricultural operations of the district.  Until, therefore, this great impediment to the drainage of the Level could be removed, it was clear that no inland works could be of any permanent advantage.  The remedy which Mr. Rennie proposed was, to cut off the great bend in the Ouse by making a direct new channel from Eau Brink, near the mouth of Marshland Drain, to a point in the river a little above the town of Lynn, as shown in the plan on the next page.  The cut was to be about three miles in length, and of sufficiently capacious dimensions to contain the whole body of the river.  By thus shortening the line of the stream, Mr. Rennie calculated that the channel would be kept clear of Silt by the greater velocity of the current, and that the fresh waters would at the same time be able to force their way out to sea without difficulty.

 


    An Act was accordingly obtained, enabling the Eau Brink to be cut; but several years passed before any steps were taken to carry out the works.  They were not actually begun until the year 1817, when Mr. Rennie was formally appointed the chief engineer.  After about four years' labour the cut was finished and opened, and its immediate effect was to give great relief to the whole of the district watered by the Ouse.  An extra fall of not less than five feet and a half was obtained at St. German's, by which the surface of the waters throughout the whole of the Middle and South Levels was reduced in proportion.  Thus the pressure on all the banks along the rivers of the Level was greatly relieved, whilst inundations were prevented, and the sluices provided for the evacuation of the inland waters were enabled effectually to discharge themselves.

 

A typicalLincolnshire landscape: Metheringham Fen, farmland south of Little Drove.
© Copyright Ian Carrington and licensed for reuse under this Creative Commons Licence.


    By labours such as these an immense value has been given to otherwise worthless swamps and wastes.  The skill of the engineer has enabled the Fen farmers to labour with ever-increasing profit, and to enjoy the fruits of their industry in comparative health and comfort.  No wonder that they love the land which has been won by toil so protracted and so brave.  Unpicturesque though the Fens may be to eyes accustomed to the undulating and hill country of the western districts of England, they nevertheless possess a humble beauty of their own, especially to eyes familiar to them from childhood.  The long rows of pollards, with an occasional windmill, stretching along the horizon as in a Dutch landscape—the wide extended flats of dark peaty soil, intersected by dykes and drains, with here and there a green tract covered with sleek cattle—have an air of vastness, and even grandeur, which is sometimes very striking.  To this we may add, that the churches of the district, built on sites which were formerly so many oases in the watery desert, loom up in the distance like landmarks, and are often of remarkable beauty of outline.

    It has been said of Mr. Rennie that he was the greatest "slayer of dragons" that ever lived,—this title being given in the Fens to persons who, by skill and industry, have perfected works of drainage, and thereby removed the causes of sickness and disease, typified in ancient times as dragons or destroyers. [p.305]  In this sense, certainly, Mr. Rennie is entitled, perhaps more than any other man, to this remarkable appellation.


――――♦――――

 
CHAPTER VI.

MR. RENNIE'S BRIDGES.
 

London Bridge, rebuilt at in Lake Havasu City, Arizona, in 1971, the sole survivor of
Rennie's three great Thames bridges.  Picture Wikipedia (Aran Johnson).


THE bridges erected by our engineer are amongst the finest of his works, and sufficient of themselves to stamp him as one of the greatest masters of his profession.  We have already given a representation of his first bridge, erected over the Water of Leith, near Edinburgh, the forerunner of a series of similar structures unrivalled for solidity and strength, contrived with an elegance sometimes ornate, but for the most part of severe and massive simplicity.

    Unlike some of his contemporaries, Mr. Rennie did not profess a disregard for theory; for he held that true practice could only be based on true theory.  Taken in the sense of mere speculative guessing, however ingenious, he would have nothing to do with it; but as matter of inference and demonstration from fixed principles, he held by theory as his sheet-anchor.  His teacher, Professor Robison, had not failed to impress upon him its true uses in the pursuit of science and art; and he never found reason to regret the fidelity with which he carried out his instructions in practice.

    In the year 1793, Mr. Rennie had the advantage of much close personal intercourse with his old friend the Professor, who paid him a visit at his house in London, for the express purpose of conferring with him upon mechanical subjects.  In the letter announcing the object of his visit, Dr. Robison candidly avowed that it was in order "that he might extract as much information from him as possible."  The Doctor had undertaken to prepare the articles on Mechanics for the third edition of the 'Encyclopedia Britannica,' and he believed he should be enabled to impart an additional value to his writings by throwing upon them the light of Rennie's strong practical judgment.  He proposed to take a lodging in the immediate neighbourhood of Rennie's house, then in Great Surrey Road, and to board with him during the day; but Rennie would not listen to this proposal, and insisted on being the Professor's entertainer during the period of his visit.

    One of the points which he particularly desired to discuss with Mr. Rennie was the theory of the equilibrium of arches—a subject at that time very imperfectly understood, but which the young engineer had studied with his usual energy and success.  He had clearly proved that the proper proportion and depth of the key-stone to that of the extrados (or exterior curve) should be in proportion to the size and form of the arch and the materials of which it was composed; and he had also established the ratio in which the arch-stones should increase from the key-stone to the piers or abutments.

    Up to this time there had been no rules laid down for the guidance of the engineer or architect,—who worked very much in the dark as to principles; and it was often a matter entirely of chance whether a bridge stood or fell when the centres were removed.  According to the views of Hutton and Attwood, the weight upon the haunches and abutments, to put the arch in a state of equilibrium so that it should stand, was unlimited; whereas Mr. Rennie established the limit to which the countervailing force or weight on the extrados should be confined.  Hence he adopted the practice of introducing a flat inverted arch between the extrados of each two adjoining arches, (at the same time increasing the width of the abutment,)—the radii of the voussoirs or arch-stones being continued completely through them.  And in order to diminish the masonry, the lower or foundation course was inclined also,—thus combining the work more completely together, and enabling it better to resist the lateral thrust.

    Dr. Robison had much discussion with Mr. Rennie on these and many other points, and the information he obtained was shortly after worked up into numerous original contributions of great value; amongst which may be mentioned his articles in the 'Encyclopedia' on the Arch, Carpentry, Roof, Waterworks, Resistance of Fluids, and Running of Rivers [p.308]—on all of which subjects Mr. Rennie had communicated to him much original information.  It may readily be imagined that the evenings devoted by Dr. Robison to conversation and discussion on such topics at Rennie's house were of interest and advantage to both; and when the Doctor returned to his Edinburgh labours, he carried with him the cordial affection and respect of the engineer, who continued to keep up a correspondence with him until the close of his life.

    In the early part of his career Mr. Rennie was called upon to furnish designs of many bridges, principally in Scotland, which, however, were not carried out, in most cases because the requisite funds could not be raised to build them.  Thus, in 1798, he designed one of eight cast-iron arches to span the river Don at Aberdeen.  Four years later he was called upon to furnish further designs, when he supplied three several plans, two of granite bridges; but the structures were of too costly a character, and the people of Aberdeen did not carry them out.

    The first important bridge which Mr. Rennie was authorised to execute was that across the Tweed at Kelso, and it afforded a very favourable specimen of his skill as an architect.  It was designed in 1799 and opened in 1803.  It consists of five semi-elliptical arches of 72 feet span, each rising 28 feet, and four piers each 12 feet thick, with a level roadway 23 feet 6 inches wide between the parapets, and 29 feet above the ordinary surface of the river.  The foundations were securely laid upon the solid rock in the bed of the Tweed, by means of coffer-dams, and beneath the deepest part of the river.  The Piers and abutments were ornamented with three-quarter columnar pilasters of the Roman Doric order, surmounted by a plain block cornice -and balustrade of the same character. The whole of the masonry was plain rustic coursed work, and in style and execution it was regarded as one of the most handsome and effective structures of its kind.

 


The Kelso Bridge may almost be said to have formed the commencement of a new era of bridge-building in this country. The semi-elliptical arches, the columnar pilasters on the piers, the balustrade, and the level roadway, are the same as in Waterloo Bridge, except as regards size and character; so that Kelso Bridge may be regarded as the model of the greater work. We believe it was one of the first bridges in this country constructed with a level roadway.

Some of the old-fashioned bridges were excessively steep and to get across them was like climbing over the roof of a house. There was a heavy pull on one side and a corresponding descent on the other. The old bridge across the Esk at Musselburgh, forming part of the high road between Edinburgh and London, was of this precipitous character. It was superseded by a handsome and substantial bridge, with an almost level roadway, after a design by Rennie. When the engineer was taking the work off the hands of the contractor, one of the magistrates of the town, who was present, asked a countryman who was passing at the time With his cart how he liked the new brig? "Brig!" said the man, "it's nae brig ava! ye neither ken whan ye're on't, nor whan ye're off't!"

 


Mr. Rennie's boldness in design grew with experience, and when consulted as to a bridge near Paxton, over the Whitadder (a rapid stream in Berwickshire), he proposed, in lieu of the old structure, which had been carried away by a flood, a new one of a single arch of 150 feet span; but unhappily the road trustees could not find the requisite means for carrying it into effect.

 

Rennie's bridge over the River Esk at Musselburgh, East Lothian, Scotland.  Picture Wikipedia (Renata).


    Another abortive but grand design was proposed by him in 1801.  He had been requested by the Secretary of State for Ireland to examine the road through North Wales to Holyhead, with the object of improving the communication with Ireland, which was then in a wretched state.  The connection of the opposite shores of the Menai Strait by means of a bridge was considered an indispensable part of any improvement of that route; and Mr. Rennie proposed to accomplish this object by a single great arch of cast iron 450 feet in span,—the height of its soffit or crown to be 150 feet above high water at spring tides. [p.312]  A similar bridge of 350 feet span, having its crown 100 feet above the same level, was also proposed by him for the crossing of Conway Ferry.

    These bridges were to be manufactured after a plan invented by Mr. Rennie in 1791, and communicated by him to Dr. Hutton in 1794; and he was strongly satisfied of its superiority to all others that had been proposed.  The designs were alike bold and skilful, and it is to be regretted that they were not carried out; for their solidity would not only have proved sufficient for the purposes of a roadway, but probably also of a locomotive railway.  In that case, however, we should have been deprived of the after-display of engineering ability in bridging the straits at Menai and the ferry at Conway.  Rennie's plans were, however, thought far too daring, and the expense of executing them far too great.  The whole subject was therefore allowed to sleep for many years, until eventually Telford spanned both these straits with suspension road bridges, and Robert Stephenson afterwards with tubular railway bridges, at a total cost of about a million sterling.

    The first bridge constructed by Mr. Rennie in England, and the earliest of his cast-iron bridges, was that erected by him over the Witham, in the town of Boston, Lincolnshire, in 1803.  [p.313]  It consists of a single arch of iron ribs, forming the segment of a circle, the chord of which is 80 feet.  It is simple yet elegant in design; its flatness and width contributing to render it most convenient for the purpose for which it was intended—that of accommodating the street-traffic of one of the most prosperous and busy towns in the Fens.

 


    Mr. Rennie's reputation as an engineer having become well established by works of this class, he was, during the remainder of his professional career, extensively consulted on this branch of construction; [p.314] and many solid memorials of his skill in bridge-work are to be found in different parts of the kingdom.  But the finest of the buildings of this character which were erected by him are unquestionably those which adorn the metropolis itself.

    The project of erecting a new bridge to connect the Strand, near Somerset House, with the Surrey side of the Thames at Lambeth, was started by a Bridge Company in 1809—a year distinguished for the prevalence of one of those joint-stock fevers which periodically seize the moneyed classes of this country.  The first plan considered was the production of Mr. George Dodds, a well-known engineer of the time.  The managing committee were not satisfied with the design, and referred it to Mr. Rennie and Mr. Jessop for their opinion.  It was found to be for the most part a copy of M. Peyronnet's celebrated bridge of Neuilly, with modifications rendered necessary by the difference of situation and the greater width of the river to be spanned.  It showed a bridge of nine arches of 130 feet span; each being a compound curve, the interior an ellipsis, and the face or exterior a segment of a circle, as in the bridge at Neuilly. [p.316]  The reporting engineers pointed out various objections to the design, as well as to the plan proposed for founding the piers.  The result was, that no further steps were taken to carry out Mr. Dodd's plan; but when the Act authorising the construction of the bridge had been obtained, the committee again applied to Mr. Rennie; and on this occasion they requested him to furnish them with the design for a suitable structure. [p.317]

    The first step which he took was to prepare an entirely fresh chart of the river and the adjacent shores, after a careful and accurate survey made by Mr. Francis Giles.  In preparing his plan, he kept in view the architectural elegance of the structure as well as its utility; and while he designed it so as to enhance the beauty of the fine river front of Somerset House, by contriving that the face of the northern abutment should be on a line with its noble terrace, he laid out the roadway so that it should be as nearly upon a level with the great thoroughfare of the Strand as possible—the rise from that street to the summit on the bridge being only 1 in 250, or about two feet in all.  Two designs were prepared—one of seven equal arches, the other of nine; and the latter being finally approved by the committee as the less costly, it was ordered to be carried into effect.

    The structure, as executed, is an elegant and substantial bridge of nine arches of 120 feet span, with piers 20 feet thick; the arches being plain semi-ellipses, with their soffits or crowns 30 feet above high water of ordinary spring tides.  Over the points of each pier are placed two three-quarter Doric column pilasters, after the design of the temple of Segesta in Sicily.  These pilasters are 5 feet 8½ inches diameter at the base, and 4 feet 4 inches at the under side of the capital, forming recesses in the roadway 17 feet wide and 5 feet deep.  The depth of the arch-stones at the crown is 4 feet 6 inches, and they increase regularly to 10 feet at the haunches.  Between each pair of arches, at the level of 19 feet above the springing, there is an inverted arch, the stones of which are 4 feet 6 inches deep at the crown, and decrease regularly on each side as they unite and abut against the extrados or backs of the voussoirs of the main haunches.  The abutments are 40 feet in thickness at the base, and decrease to 30 feet at the springing.  The cope of the arches and piers is surmounted by a Grecian Doric block-cornice and entablature, upon which is placed a balustrade parapet 5 feet high.  The total width of the bridge from outside to outside of the parapets is 45 feet.  The footpaths on each side are 7 feet wide, and the roadway for carriages 28 feet.  There were originally four sets of landing stairs two to each abutment; and the arrangement of this part of the work has been much admired, on account of its convenience, as well as because of its architectural elegance.

    In the construction of this bridge there are four features of distinctive importance to be noted:—1st. The employment of coffer-dams in founding piers in a great tidal river—an altogether new use of that engineering expedient, though now become customary.  2nd. The ingenious method employed for constructing, floating, and fixing the centres; since followed by other engineers in works of like magnitude.  3rd. The introduction and working of granite stone to an extent before unknown, and in much larger and more substantial pieces of masonry than had previously been practised. 4th.  The adoption of elliptical stone arches of an unusual width, though afterwards greatly surpassed by the same engineer in his New London Bridge.

 

Section of Waterloo Bridge.


Mr. Rennie invariably took the greatest pains in securing the most solid foundations possible for all his structures, and especially of his river works, laying them far below the scour of the river, at a depth beyond all probable reach of injury from that cause. The practice adopted in founding the Piers of the early bridges across the Thames was to dredge the bottom to a level surface, and build the foundations on the bed of the river, protecting them outside by rubble, by starlings, or by sheet-piling. Mr. Dodds had proposed to follow the method employed by Labelye at Westminster Bridge, of founding the piers by means of caissons; but Mr. Rennie insisted on the total insufficiency of this plan, and that the most effectual method was by means of coffer-dams. This would, no doubt, be more costly in the first instance, but vastly more secure; and he foresaw that the inevitable removal of the piers of Old London Bridge, by increasing the current of the river, would severely test the foundations of all the bridges higher up the stream —which proved to be the case. Having already extensively employed coffer-dams in getting in the foundations of the London and East India Dock walls, he had no doubt as to their success in this case; and they were adopted accordingly. [p.320]

 


Mr. Rennie also introduced a practice of some novelty and importance in the centering upon which the arches of the bridge were built. He adopted the braced principle. The centres spanning the whole width of the arch were composed of eight ribs each, formed in one piece, resting upon the same number of solid wedges, supported by inclined tressels placed upon longitudinal bearers, firmly fixed to the offset of the piers and abutments. At the intersecting point of the bearers or braces in each rib there was a cast-iron box, with two holes or openings in it, so that the butt-ends rested firmly against the metal; and to prevent them from acting like so many wedges to tear the rib to pieces when the vertical weight of the arch began to act upon them, pieces of hard wood were driven firmly into the holes above described, to check the effect of the bearers or struts of the ribs; and this arrangement proved completely successful. The eight ribs were firmly connected together by braces and ties, so as to form one compact frame, and the curve or form of the arch was accurately adjusted by means of transverse timbers, 12 inches wide and 6 inches thick, laid across the whole of the ribs, set out to the exact form of the curve by ordinates from the main or longitudinal axis of the ellipsis; and in proportion as the voussoirs or arch-stones were carried up from the adjoining piers, the weight which had been laid upon the top of the centre to keep it in equilibrium according to the form of the arch during construction, was gradually removed as it advanced towards completion. When the arch was about two-thirds completed, a small portion of it was closed with the centre, and the remaining part of each side was brought forward regularly by offsets to the crown until the whole was finished. Each key-stone was accurately fitted to its respective place, and the last portion of each, for the space of about eighteen inches, was driven home by a heavy wooden ram or pile-engine, so as almost to raise the crown of the arch from the centre.

About ten days after the main arches had been completed, and the inverts and spandrel walls between them carried up to the proper height, the arches were gently slackened, to the extent of about two inches, so as to bring each to its bearing to a certain extent. This was effected by driving back the wedges upon which the ribs of the centres rested, by means of heavy wooden rams attached to them, so that they could swing backwards and forwards with great facility when any external force was applied to them; and this was done by ropes worked by hand-labour. After the first striking or slackening, the arches were allowed to stand for ten days, when the wedges were driven back six inches farther. After ten days more the wedges were driven back sufficiently to render the arch altogether clear of the centering. By this means the mortar was firmly imbedded into all the joints, and the arch came gradually to its ultimate bearing without any undue crushing. In order to ascertain whether any change of form took place, three straight lines were drawn in black chalk on the extreme face of the arch previous to commencing the operations of striking the centre—one horizontally in the centre of the voussoirs forming the crown, and two from the haunches of the arch, each intersecting the first line at about 25 feet on each side of the keystone; so that if there had been any derangement of the curve or irregular sinking, it would at Once have been clearly apparent. After the centres had been removed, it was found that the sinking Of the arches varied from 2½ to 3¼ inches, which was as nearly as possible the allowance made by the engineer in designing the work; the whole plan being worked out with admirable precision and accuracy.

The method of fixing and removing the centres was entirely new; being precisely the same as was afterwards followed by Mr. Robert Stephenson in fixing the wrought-iron ribs of the Conway and Britannia bridges—that is, by constructing them complete upon a platform adjacent to the river, and floating them between the piers on barges expressly contrived for the purpose. They were then raised into their proper places by four strong screws, 8 inches in diameter and 4 feet long, fixed in a strong cast-iron box firmly bedded in the solid floor of the barge. The apparatus worked so well and smoothly, that the whole centre, consisting of eight ribs, each weighing about fifty tons, was usually placed within the week.

The means employed by Mr. Rennie for forming his road upon the bridge, were identical with those adopted by Mr. Macadam at Bristol some six years later. But the arrangement constituted so small a part of our engineer's contrivance, that, as in many other cases, he made no merit of it. When the clay-puddle placed along the intended roadway was sufficiently hard, he spread a stratum of fine screened gravel or hoggins, which was carefully levelled and pressed down upon the clay. This was then covered over with a layer of equally broken flints, about the size of an egg; after which the whole was rolled close together, and in a short time formed an admirable " macadamised " road. Mr. Rennie had practised the same method of making roads over his bridges long before 1809; and he continued to adopt it in all his subsequent structures.

The whole of the stone required for the bridge (excepting the balustrades, which were brought ready worked from Aberdeen) was hewn in some fields adjacent to the erection on the Surrey side. It was transported to the work upon trucks drawn along railways, in the first instance over temporary bridges of wood; and it is a singular circumstance that nearly the whole of the material was drawn by one horse, called "Old Jack"—a most sensible animal, and a great favourite. His driver was, generally speaking, a steady and trustworthy man, though rather too fond of his dram before breakfast. As the railway along which the stone was drawn, passed in front of the public-house door, the horse and truck were usually pulled up while Tom entered for his "morning." On one occasion the driver stayed so long that "Old Jack," becoming impatient, poked his head into the open door, and taking his master's coat-collar between his teeth, though in a gentle sort of manner, pulled him out from the midst of his companions, and thus forced him to resume the day's work.

The bridge was opened with great ceremony by His Royal Highness the Prince Regent, attended by y the Duke of Wellington and many other distinguished personages, on the 18th of June 1817. It was originally named the Strand Bridge; but after that date the name was altered to that of "Waterloo," in honour of the Duke. At the opening, the Prince Regent offered to confer the honour of knighthood on the engineer, who respectfully declined it. Writing to his friend Whidbey, he said, "I had a hard business to escape knighthood at the opening." He was contented with the simple, unadorned name of John Rennie, engineer and architect of the magnificent structure which he had so successfully brought to completion.

 

 

An artist's impression of the "Strand Bridge", 1814.

 

Rennie's Waterloo Bridge, opened on the 18th June, 1817.


    Waterloo Bridge is indeed a noble work, and probably has not its equal for size, beauty, and solidity.  Dupin characterised it as a colossal monument, worthy of Sesostris or the Caesars.  Canova, during his visit to England, was particularly struck by the fact, that the trumpery Chinese bridge, in St. James's Park, should be the production of the Government, whilst Waterloo Bridge was the enterprise of a private company.  Like all Rennie's works, it was built for posterity.  That it should not have settled more than a few inches—not five in any part—after the centres were struck, is an illustration of solidity and strength probably without a parallel. We believe that not a crack is visible in the entire work. [p.326]
    The necessity for further bridges across the Thames increased with the growth of population on both sides of the river.  In the year 1813, a Company was formed to provide a bridge at some point intermediate between Blackfriars and London Bridge, of which Mr. Rennie was appointed the engineer.  The scheme was at first strongly opposed by the Corporation, on the ground of the narrowness of the river at the point at which it was proposed to erect the new structure; but the public demands being urgent, the necessary Act was at length allowed to pass, but the Corporation insisted on the provision of a very large waterway, so that the least possible obstruction should be offered to the navigation.  Mr. Rennie prepared a design to meet the necessities of the case, and in order to secure the largest waterway, he projected his well-known Southwark Bridge—extending from Queen Street, Cannon Street, to Bridge Street, Southwark.  It consists of three cast-iron arches, with two stone piers and abutments.  The arches are flat segments of circles, the centre one being not less than 240 feet span (or 4 feet larger than Sunderland Bridge, the largest cast-iron arch that had until then been erected), rising 24 feet, and springing 6 feet above high water of spring tides.  The two side arches are of 210 feet span, each rising 18 feet 10 inches, and springing from the same level.  The two piers were 24 feet wide each at the springing, and 30 feet at the base.

 

Sectional view of Southwark Bridge; "as an example of arch construction, it stands confessedly unrivalled as regards its colossal
proportions, its architectural effect, and the general simplicity and massive character of its details
" (Robert Stephenson).


    The works commenced with the coffer-dam of the south pier on the Southwark side, and the first stone was laid by Admiral Lord Keith about the beginning of 1815.  All the centering for the three arches was fixed by the autumn of 1817, and the main ribs were set by the end of April 1818.  The centres were struck by the end of the month of June following, and completely removed by the middle of October; and the, bridge was opened for traffic in March 1819.

    In the course of this work great precautions were used in securing the foundations of the piers.  The river was here at its narrowest and deepest point, the bed being 14 feet below low water of ordinary spring tides.  The coffer-dams were, therefore, necessarily of great depth and strength to resist the pressure of the strong body of water, as well as the concussion of the barges passing up and down the river, which frequently drove against them.  Hence the dams were constructed in the form most capable of resisting external pressure, and yet suitable to the dimensions of the foundations.  The masonry and iron work of the bridge were erected with great care and completeness.  The blocks of stone in the piers were accurately fitted to their places by moulds, and driven down by a heavy wooden ram.  The least possible quantity of finely tempered mortar was used, so that every part should have a perfectly true permanent bearing.  Great care was also taken in the selection of the blocks.  The exterior of the piers was constructed of hard silicious stone brought from Craigleith Quarry, near Edinburgh, and Dundee; the interior, from the bottom of the foundations to the springing of the arches, of hard Yorkshire grit; while that part of the piers and abutments from which the arches spring consisted of the hardest and closest blocks of Cornish and Aberdeen granite: in fine, it may be affirmed that a more solid piece of masonry does not exist than Southwark Bridge.

 


    The iron work consists of eight arched ribs, the main strength of the arches being embodied in their lower parts, which are solid.  The lower or main arch is divided into thirteen pieces, with a rib 5½ inches thick at the top and bottom, and 2½ inches in the centre.  The joints radiate outwards from the lower edge, and form so many cast-iron instead of stone voussoirs, from 6 to 8 feet deep and 13 feet long.  At the junction of each of these main rib pieces there are transverse plates of the same depth, having flanges cast upon them on both sides in a wedge form, so that the ends of the main rib piers fit into them on one side, whilst on the other there is a cast-iron wedge, driven in between the rib and flange piece, and enabling the whole to be accurately adjusted and connected together.  In addition to this, each rib piece had a flange, cast at each end with a certain number of holes three-quarters of an inch in diameter, into which wrought-iron screw bolts were introduced to connect the whole firmly together in the direction of the arch.  These rib pieces were also of great importance during construction, the chief dependence being placed upon their lateral thrust in holding the arches together.

    At each pier and abutment there was a similar cast-iron bed or abutting plate, let accurately 1½ inch into the stone; but between the end of each main rib which sprang from this plate there was a groove cut out of the solid stone behind the springing plates and main iron ribs of the arches, inches wide, 3 inches thick at the top, and 2 inches at bottom.  The groove was accurately dressed and polished.  Three cast-iron wedges, 9 feet long, 6 inches wide, and 3¼ inches thick at top and 2 inches at bottom, were then made and most accurately chipped and filed, so as to fit exactly the groove above mentioned to within 12 inches of its bottom.  When the whole of these wedges at both ends of the arch had been put into their places, they were carefully driven home to the bottom of the grooves at the same time by heavy wooden rams, by which means the ribs of the arches were relieved from the centres and took their own bearing.  In other words, the arches were keyed from the abutments only, instead of from the centre, as is usual in bridges of stone.

    This was an extremely delicate and nice process, as it required that the variations of the thermometer should be carefully observed, in order that each operation should be carried on at as nearly as possible the same degree of temperature, otherwise the form of the arch would have been distorted, the vertical and lateral pressure of the different parts would have been affected, and an undue strain thrown upon the abutments as well as the different parts of the arch.  But so nicely was the whole operation arranged and adjusted, that nothing of the kind occurred: the parts remained in perfect equilibrium; not a bolt was broken, and not the smallest derangement was found in the structure after the process had been completed.

    The spandrel pieces attached to the top of the main ribs were cast in the form of open diamonds or lozenges, connected together in the transverse direction by two tiers of solid crosses laid nearly horizontally—all closely wedged and firmly bolted together. In addition to the transverse connecting plates cast in open squares, there were also diagonal braces of cast iron, commencing at the extremity of the outer rib of each arch and intersecting each other so as to form a diamond-shaped space in the centre.  These were also secured at their ends by wedges and bolts, like the main rib pieces.

    After the main ribs of the arches were relieved from the centres, and had taken their bearing, before the centres were removed from beneath them, experiments were made how far they might be affected by expansion and contraction, in proportion to the different degrees of temperature to which the bridge might be exposed; and for this purpose different gauges were made of brass, iron, and wood.  These gauges were firmly attached to the middle or crown of the wooden centres, and divided into sixteenths of an inch, and at each a Fahrenheit thermometer was placed; so that the ends of the arch being fixed, the variation in the temperature would be indicated by the rise and fall in the centre.  The observations were made daily in the morning, at midday, and at sunset—for several months during summer and winter, when it was ascertained that the arches rose and fell about one-tenth of an inch for every 10 degrees of temperature, more or less.

    The whole iron work is covered with solid plates, having flanges cast on their upper side.  These plates are laid in the transverse direction and on the top of the spandrel walls, so that they form a solid and compact cast-iron floor to support the roadway.  The cornice, which is cast hollow, is of the plain Roman-Doric order, and is secured to the roadway-plates by strong stays and bolts at proper intervals.  The parapet consists of a plinth, also cast hollow, with a groove at the top to receive the railing, which is cast in the form of open diamonds corresponding with the spandrels.  The roadway is 42 feet wide from outside to outside, and formed in the same manner as that over Waterloo Bridge, which has been already described.

    The total quantity of cast iron in the bridge is 3,620 tons, and of wrought iron 112 tons.  It has been said that an unnecessarily large quantity of material has been employed; and no doubt a lighter structure would have stood.  But looking at the imperfections of workmanship and possible flaws in the castings, Mr. Rennie was probably justified in making the strengths such as he did, in order to ensure the greatest possible solidity and durability—qualities which eminently characterise his works, and perhaps most of all, his majestic metropolitan bridges.  Although the Southwark Bridge was built before the Railway era, which has given such an impetus to the construction of iron bridges, it still stands pre-eminent in its class, and is a model of what a bridge should be.  Its design was as bold as its execution was masterly.  Mr. Robert Stephenson has well said of it that, "as an example of arch construction, it stands confessedly unrivalled as regards its colossal proportions, its architectural effect, and the general simplicity and massive character of its details." [p.334]

 


――――♦――――

 
CHAPTER VII.

THE BELL ROCK LIGHTHOUSE.
 

Picture Internet Text Archive.


ABOUT eleven miles east of the mainland of Scotland, near the entrances to the Friths of Forth and Tay, lies an extensive ledge of rocks, which for a long time was the terror of the seamen navigating that coast.  It is nearly two miles in length, being the crest of a mountain rising from the sea bottom, only a small part of which is visible at high water.

    This sunken reef was a source of such peril, that, as early as the fourteenth century, the Abbot of Arbroath caused a bell to be placed upon the principal rock, the swinging of which by the motion of the waves warned seamen of its dangers; and from this circumstance it came to be called the Bell Rock.  It is affirmed that a notorious pirate, in order to plague the Abbot, cut the bell from the rock, but was himself afterwards wrecked on the very spot; and on this tradition Southey founded his beautiful ballad of 'Ralph the Rover.' [p.335]  Nothing was done to replace the bell, or to set a beacon upon the reef; and it remained in its dangerous state—the Eddystone of the northern seas—until the beginning of the present century, when the increasing commerce of Scotland, and the large number of vessels wrecked there, had the effect of directing public attention to the subject.  As in the case of the Eddystone reef, the sailors' fear of it was such, that in order to avoid its dangers, they hugged the land so close as very frequently to run ashore.

    Captain Basil Hall relates that when a boy, he was constantly hearing of vessels getting wrecked through fear of the terrible Bell Rock, which lay about ten leagues due north of the house at Dunglass in which he was born.  It is situated on the borders of East Lothian, not far from the bold promontory on which Fast Castle stands, overlooking the German Ocean.  He states that "ships bound for the Forth, in their constant terror of the dangerous reef, were not content with giving it ten or even twenty miles of elbow-room, but must needs edge off a little more to the south, so as to hug the shore, in such a way that, when the wind chopped round to the northward, as it often did, these over-cautious navigators were apt to get embayed in a deep bight to the westward of Fast Castle.  If the breeze freshened before they could work out, they paid dearly for their apprehensions of the Bell Rock, by driving upon ledges fully as sharp, and far more extensive and inevitable.  "Thus," he says, "at that time, from three to four, and sometimes half-a-dozen, vessels used to be wrecked every winter, within a mile or two of our very door." [p.337]

 


    A Board of Commissioners had been appointed, under the powers of an Act passed in 1786, for the purpose of erecting lighthouses at the most dangerous parts of the coast of Scotland; and by the end of the century several had been built,—one on the Isle of May at the entrance of the Frith of Forth, another on the Cumbraes at the mouth of the Frith of Clyde, and others on rocky promontories on the eastern and western coasts, including the Orkneys.  The lights exhibited were of a rude kind, and consisted of coal fires in chauffers.  All that was needed being a bright light, they probably answered their purpose, though in a clumsy way.  The most dangerous reef of all, however, was still left without any protection; and doubtless the delay in providing a light upon the Bell Rock arose from the great difficulty and expense of erecting a suitable structure on such a site.

    In the winter of 1799, a tempest memorable for its violence and fatal effects, ravaged the coasts, and drove from their anchors all the ships lying in Yarmouth Roads.  The greater number were wrecked on the northern coast; and it was believed that many of them might have been saved, had a light been fixed on the Bell Rock to point out the entrances to the Friths of Forth and Tay.  Among the other lamentable shipwrecks which took place on the Inchcape about the same time, was that of the 'York,' a seventy-four-gun ship, which went down with all her crew.  The reef was also a constant source of danger to the shipping of Dundee, then rising in importance, as it lay right in the main track of vessels making for the mouth of the Tay from the German Ocean.

    Many were the plans suggested for a lighthouse on the Bell Rock.  In 1799 Captain Brodie submitted to the Commissioners of Northern Lights his design of a cast-iron tower to be supported on four pillars; but it was not adopted.  In the mean time temporary beacons of timber were employed; but these rarely stood the storms of a single winter; and three successive structures of this kind were completely swept away.  Mr. Robert Stevenson and Mr. Downie also proposed plans for the consideration of the Board between 1800 and 1804; but neither of them was adopted.

    Considerable diversity of opinion continuing to exist, the Commissioners determined to employ Mr. Rennie to examine the site and report as to the best course to be pursued.  He accordingly proceeded to Scotland, and visited the Inchcape Rock on the 17th of August, 1805, in company with Mr. Hamilton, one of the Commissioners, and Mr. Stevenson, their surveyor.

    After mature deliberation, Mr. Rennie sent in his report on the 30th of December following.  He recommended the erection of a substantial lighthouse of stone, similar to that on the Eddystone, as being, in his opinion, the only structure calculated to meet the necessities of the case. [p.338]  He regarded a wooden building as objectionable, because of the perishable nature of the material, and its liability to be destroyed by fire.  Although it would be possible to erect a lighthouse of cast iron, its cost at that time would have been equal to one of stone, with which, in point of durability, it was not to be compared.  "I have therefore," he concluded, "no hesitation in giving a decided opinion in favour of a stone lighthouse."  With such examples as the Tour de Cordovan near the entrance of the Garonne, and the Eddystone off the coast of Cornwall, he held that there could be no doubt as to the superiority of this plan to any other that could be proposed.  Although the Inchcape was not so long uncovered by the tide as the Eddystone rock, and there might be greater delay in getting in the first four or five courses of the foundation, this was only a question of time; and he had no doubt that this difficulty would be overcome, and the whole structure completed in the space of about four years.

    In his report he further said: "Mr. Stevenson, to whose merit I am happy to bear testimony, has been indefatigable in obtaining information respecting this rock, and he has made a model of a stone lighthouse nearly resembling that of the Eddystone, in which he has proposed various ingenious methods of constructing the work by way of facilitating the operations.  I own, however, after fully considering them, and comparing them with the construction of Mr. Smeaton—I mean in the process of building—and also reflecting that there are undoubted proofs of the stability of the Eddystone, that I am inclined to give the latter the preference; its general construction, in my opinion, rendering it as strong as can well be conceived."

    Taking, however, into account, that the foundation of the proposed building lay so much lower in the sea, Mr. Rennie suggested that the column should be somewhat higher, so that the eave of the cupola should be about 100 feet above the surface of the rock, the Eddystone being only 84 feet 6 inches,—though this alteration would involve a somewhat greater diameter of the base.  He further pointed out that the pillar should be surrounded by such an extent of rock as to diminish the force of the waves breaking at its foot.  He also proposed that the floor of the lower room of the lighthouse should be 50 feet above the level of the rock, and from thence to the top of the platform 35 feet; making a total height of 85 feet to the platform or gallery.  He recommended that argand lights should be employed, with parabolic reflectors; and he suggested for consideration the employment of carburetted hydrogen gas, then coming into extensive use for lighting purposes.  The cost of the lighthouse, so constructed, he estimated at about £42,000.

    The Commissioners adopted Mr. Rennie's report, and proceeded to Parliament for the requisite powers, which were obtained in the session of 1806; after which (on the 3rd of December following) they unanimously appointed him the chief engineer for conducting the work.  At Mr. Rennie's recommendation, Mr. Stevenson was appointed the assistant-engineer to superintend the operations on the spot, and he placed under him two able foremen superintendents, Mr. Peter Logan over the masons, and Mr. Francis Watt over the joiners employed upon the lighthouse.  Mr. Rennie was then requested to report further, with plans and specifications of the various works in detail; which he prepared and duly submitted to the Board.

 

Robert Stevenson (1772–1850), Scottish civil engineer and specialist in lighthouse construction. Picture: The Internet Text Archive.


    In this second report of the 26th December following, Mr. Rennie entered at great length into the description of stone to be used in the building, based upon a personal inspection of the quarries at Mylnefield near Dundee, at Arbroath, and at Aberdeen; and on his recommendation it was determined to use blocks from the Rubieslaw quarry at Aberdeen for the outer, and Dundee stone for the inner masonry.  He also repeated his advice, that in carrying out the work, the plan of construction adopted by Smeaton in building the lighthouse on the Eddystone should be mainly followed; one of the few deviations consisting in the substitution of dovetailed pieces of stone for chain bars in the joints both of the walls and the floors.  These recommendations having been adopted, Mr. Rennie was authorised to proceed with the requisite preparations for the building; and, after making all due arrangements, and giving his representatives suitable instructions, he left the practical operations to be carried out by them accordingly. [p.341]

    The whole of the year 1807 was occupied in constructing the necessary vessels, and in erecting the requisite machinery and building-shops at the working yard at Arbroath, which was fixed upon as the most convenient point on the coast for carrying on the land operations.  Some progress had been made at the rock itself, where a smith's forge was fixed and a temporary beacon erected, while a floating light, fitted up in an old fishing dogger, was anchored near the reef until the lighthouse could be erected.  Preparations had also been made for proceeding with the foundations, the necessary excavations being conducted at considerable peril, in consequence of the violence of the waves and the short period during which the reef was uncovered during each day.

    The dangerous nature of the employment may be illustrated by the following brief account of an accident which happened to the workmen on the 2nd of September, before the excavation for the first course had been completed.  An additional number of masons had that morning come off from Arbroath in the tender of forty tons, named 'The Smeaton,' and having landed them on the rock, the vessel rode at salvagee, with a crosshead made fast to the floating buoy.  The wind rising, the men began to be uneasy as to the security of the 'Smeaton's' riding-ropes, and a party went off in a boat to examine whether she was all secure; but before they could reach the vessel's side they found she had already gone adrift, leaving the greater part of the men upon the reef, in the face of a rising tide.

 

Stevenson's 'improved' lighting apparatus.  The Bell Rock was the first lighthouse that was illuminated by Mr. Stevenson's 'improved' apparatus (shown above), where a is the fountain for the oil, b the burner, and the directions of the incident and reflected rays are represented by dotted lines.  Picture: The Internet Text Archive.


    By the time the 'Smeaton's' crew had got her mainsail set and made a tack towards their companions, she had drifted about three miles to leeward, with both wind and tide against her, and it was clear that she could not possibly make the rock until long after it had been completely covered.  There were thirty-two men in all upon the Inch-cape, provided with but two boats, capable of carrying only twenty-four persons in fine weather.  Mr. Stevenson seems to have behaved with great coolness and presence of mind on the occasion, though he confessed that of the two feelings of hope and despair, the latter largely predominated.  Fully persuaded of the peril of the situation, he kept his fears to himself, and allowed the men to continue engrossed with their occupations of boring and excavating.

    After working for about three hours, the water began to rise along the lower parts of the foundations, and the men were compelled to desist.  The forge fire became extinguished; the smith ceased from hammering at his anvil, and the masons from hewing and boring; and when they took up their tools to depart, and looked around, their vessel was not to be seen, and the third of their boats had gone after the 'Smeaton,' which was drifting away in the distance!  Not a word was uttered; but the danger of their position was instantly comprehended by all.  They looked towards their master in silence; but the anxiety which had been growing in his mind for some time had now become so intense, that he was speechless.  When he attempted to speak, his mouth was so parched that his tongue refused utterance.  Turning to one of the pools on the rock, he lapped a little water, which gave him relief, though it was salt; but what was his happiness when, on raising his head, some one called out "A boat! a boat!" and sure enough, a large boat was seen through the haze making for them.  She proved to be the Bell Rock pilot-boat, which had come off from Arbroath with letters, and her timely arrival doubtless saved the lives of the greater part of the workmen.  They were all taken off and landed in safety, though completely drenched and exhausted.

 

Temporary living quarters on the Bell Rock while the lighthouse was under construction.  [p.343]  Picture: The Internet Text Archive.


    Mr. Rennie, accompanied by his son George, visited the rock on the 5th of October, 1807, the day before the works were suspended for the winter.  They came off from Arbroath, and stayed on board the lighthouse yacht all night, where Mr. Stevenson states that he "enjoyed much of Mr. Rennie's interesting conversation, both on general topics and professionally upon the progress of the Bell Rock works, on which he was consulted as chief engineer."  On the following morning Mr. Rennie landed to inspect the progress made in the excavation, being received with a display of colours from the beacon and three cheers from the workmen.  They continued at work for only about three hours that day, after which the whole working party, accompanied by the chief engineer and his son, the resident engineer, and the foreman of the works, returned to land for the winter.

 

Picture: The Internet Text Archive.


    The preparation of the stone blocks for next summer's operations then proceeded on shore; and by the spring large numbers were dressed, and ready to be floated off.  In May, 1808, the excavations on the rock were proceeded with, and on the l0th of July the first stone was laid with considerable ceremony.  Mr. Rennie paid his next visit on the 25th of November following, for the purpose of inspecting the work done, and reporting progress to the Commissioners.  From his report it appears that three courses of masonry had by that time been laid in a very complete manner.  At his suggestion, a modification was adopted in the cement used for the building, and also in the use of the granite blocks delivered from the Aberdeen quarry, some of which had been found defective.

 


    By the end of 1809, at our engineer's next visit of inspection, the tower had been built to a height of 30 feet, and was comparatively secure against the effects of the most violent seas.  In his report to the Commissioners he stated that he found that the form of slope which he had adopted for the base of the tower, as well as the curve of the building, fully answered his expectations—that they presented comparatively small obstruction to the roll of the waves, which played round the column with ease—and he expressed the opinion that the lighthouse, when finished, "would be found to be the most perfect work of its kind."  In his report he recommended a modification in the details of the upper part of the building.  In dovetailing the stones together, the method employed at the Eddystone had up to this point been followed; but from the top of the staircase he proposed that a somewhat different plan should be adopted.

    "The stone floors in the Eddystone," he said, "were formed by an arch in the shape of a dome springing from the surrounding walls, to strengthen which chain bars were laid in the walls.  I propose that these should be done with large stones radiating from a circular block in the middle, to which their interior ends are to be dovetailed as well as the radiated joints, and these connected to the surrounding walls by means of a circular dowel.  By this means the lateral pressure on the walls will be removed, the whole connected together as one mass, and no chain-bars will be wanted except under the cornice.  Thus the whole will be like a solid block of stone excavated for the residence of the lightkeepers, stores," &c.  He concluded with some practical advice as to the construction of the lantern after an improved method which he proposed, in order that it might be in readiness in the course of the ensuing summer, by which time he anticipated that the building would be ready for use if the weather proved favourable.  These recommendations were adopted, and the work having proceeded satisfactorily, the whole was completed by the end of 1810, and the light was regularly exhibited after the 1st of February, 1811.

    When finished, the tower was 10 feet higher than the original design, being 95½ feet to the top of the cornice, and 127 feet to the top of the lantern.  The additional height to which Mr. Rennie thought it necessary to carry the lighthouse during its construction, had the effect of raising the total cost to £61,331; but he believed that the increased outlay would be fully justified by the greater security of the lighthouse and its increased efficiency for the purpose for which it was intended.

    Notwithstanding the facts which we have stated, showing that Mr. Rennie acted throughout as the chief engineer of the lighthouse—that he furnished the design, arranged the details of the building, settled the kind of materials to be used, down even to the mode of mixing the mortar, and from time to time made various alterations and modifications in the plans of the work during its progress, with the sanction of the Commissioners—his name has not usually been identified with the erection of the structure; the credit having been almost exclusively given to Mr. Robert Stevenson, the resident engineer,—arising, no doubt, from the circumstance of Mr. Rennie being in a great measure ignored in the 'Account of the Bell Rock Lighthouse,' published by Mr. Stevenson several years after the death of Mr. Rennie.

    The following account was given by Mr. Rennie himself, in a letter to Matthew Boulton of Birmingham, [p.347] relative to his own and Mr. Stevenson's connection with the plans and erection of the lighthouse:—


    "Mr. Robert Stevenson was bred a tinsmith and lamp-maker, in which line he was employed by a Mr. Thomas Smith, a considerable manufacturer in Edinburgh, who had the care of the reflectors and lamps belonging to the Commissioners of Northern Lights.  While in Smith's employment Stevenson married his daughter, and Smith, advancing in years, employed Stevenson to look after the Northern Lights.  This he did for several years.  When Smith declined the situation, Stevenson was elected in his place.

    "When the Bell Rock Lighthouse was erected, Stevenson was employed to superintend the whole.  A regular head mason and carpenter were employed under him.  The original plans were made by me, and the work was visited by me from time to time during its progress.  When the work was completed, Stevenson considered that he had acquired sufficient knowledge to start as a civil engineer, and in that line he has been most indefatigable in looking after employment, by writing and applying wherever he thought there was a chance of success.

    "He has assumed the merit of applying coloured glass to lighthouses, of which Huddart was the actual inventor, and I have no doubt that he will also assume the whole merit of planning and erecting the Bell Rock Lighthouse, if he has not already done so.  I am told that few weeks pass without a puff or two in his favour in the Edinburgh papers"  *  *  *


    Mr. Stevenson was unquestionably entitled to great merit for the able manner in which he performed his duties as a superintendent in connection with the building of the Lighthouse.  Mr. Rennie was always ready to acknowledge this.  But had any failure occurred in consequence of a defect in the plans, Mr. Rennie, and not Mr. Stevenson, would have been held responsible.  As, however, the Lighthouse proved a success, it is but fair that the chief engineer should not be deprived of the merit which unquestionably belonged to him.  It is a matter of impossibility that engineers in extensive practice should personally superintend the various structures designed by them, and which are proceeding at the same time in different parts of the country.  Hence the appointment, at their recommendation, of superintendents or resident engineers, whose business it is to see that the details of the design are faithfully carried out, and that the work is executed in all respects according to the chief engineer's designs and instructions.

 


    To take two instances—Telford's Menai Bridge and Stevenson's Britannia Bridge—in the former of which cases Mr. Provis was appointed resident engineer, and in the latter Mr. Edwin Clarke.  Both of these gentlemen afterwards published detailed histories of these works; but neither of them ignored the chief engineer, nor did they claim the exclusive merit of having been the successful erectors of these magnificent structures.

 

Bell Rock Lighthouse.  Picture Wikipedia (Derek Robertson  mod. cactus.man). [p.350]


    During Mr. Rennie's lifetime various notices were published, claiming for Mr. Stevenson the sole credit of having designed and erected the lighthouse.  At this Mr. Rennie was naturally annoyed; and the more so when he learnt that Mr. Stevenson was about to "write a book" without communicating with him on the subject.  "I have no wish," he says, in a letter to a friend, "to prevent his writing a book.  If he details the truth fairly and impartially, I am satisfied.  I do not wish to arrogate to myself any more than is justly my due, and I do not want to degrade him.  If he writes what is not true, he will only expose himself.  I bethink me of what Job said, 'Oh that mine enemy would write a book!'"  The volume, however, was not published till three years after Rennie's death; and it was not until the publication of Sir John's work on Breakwaters, that his father's claims as chief and responsible engineer of the lighthouse were fairly asserted and afterwards fully and clearly established. [p.351]


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