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CHAPTER XVII.

ROBERT STEPHENSON'S CAREER—THE STEPHENSONS AND BRUNEL—EAST COAST ROUTE TO SCOTLAND—ROYAL BORDER BRIDGE, BERWICK—HIGH-LEVEL BRIDGE, NEWCASTLE.

The career of George Stephenson was drawing to a close. He had for some time been gradually retiring from the more active pursuit of railway engineering, and confining himself to the promotion of only a few undertakings, in which he took a more than ordinary personal interest. In 1840, when the extensive main lines in the Midland districts had been finished and opened for traffic, he publicly expressed his intention of withdrawing from the profession. He had reached sixty, and, having spent the greater part of his life in very hard work, he naturally desired rest and retirement in his old age. There was the less necessity for his continuing "in harness," as Robert Stephenson was now in full career as a leading railway engineer, and his father had pleasure in handing over to him, with the sanction of the companies concerned, nearly all the railway appointments which he held.

Robert Stephenson amply repaid his father's care. The sound education of which he had laid the foundations at school, improved by his subsequent culture, but more than all by his father's example of application, industry, and thoroughness in all that he undertook, told powerfully in the formation of his character not less than in the discipline of his intellect. His father had early implanted in him habits of mental activity, familiarized him with the laws of mechanics, and carefully trained and stimulated his inventive faculties, the first great fruits of which, as we have seen, were exhibited in the triumph of the "Rocket" at Rainhill. "I am fully conscious in my own mind," said the son at a meeting of the Mechanical Engineers at Newcastle in 1858, "how greatly my civil engineering has been regulated and influenced by the mechanical knowledge which I derived directly from my father; and the more my experience has advanced, the more convinced I have become that it is necessary to educate an engineer in the workshop. That is, emphatically, the education which will render the engineer most intelligent, most useful, and the fullest of resources in times of difficulty."

Robert Stephenson was but twenty-six years old when the performances of the "Rocket" established the practicability of steam locomotion on railways. He was shortly after appointed engineer of the Leicester and Swannington Railway; after which, at his father's request, he was made joint engineer with himself in laying out the London and Birmingham Railway, and the execution of that line was afterward intrusted to him as sole engineer. The stability and excellence of the works of that railway, the difficulties which had been successfully overcome in the course of its construction, and the judgment which was displayed by Robert Stephenson throughout the whole conduct of the undertaking to its completion, established his reputation as an engineer, and his father could now look with confidence and pride upon his son's achievements. From that time forward, father and son worked together cordially, each jealous of the other's honor; and on the father's retirement it was generally recognized that, in the sphere of railways, Robert Stephenson was the foremost man, the safest guide, and the most active worker.

Robert Stephenson was subsequently appointed engineer of the Eastern Counties, the Northern and Eastern, and the Blackwall Railways, besides many lines in the midland and southern districts. When the speculation of 1844 set in, his services were, of course, greatly in request. Thus, in one session, we find him engaged as engineer for not fewer than thirty-three new schemes. Projectors thought themselves fortunate who could secure his name, and he had only to propose his terms to obtain them. The work which he performed at this period of his life was indeed enormous, and his income was large beyond any previous instance of engineering gain. But much of the labor done was mere hackwork of a very uninteresting character. During the sittings of the committees of Parliament, much time was also occupied in consultations, and in preparing evidence or in giving it.

The crowded, low-roofed committee-rooms of the old houses of Parliament were altogether inadequate to accommodate the press of perspiring projectors of bills, and even the lobbies were sometimes choked with them. To have borne that noisome atmosphere and heat would have tested the constitutions of salamanders, and engineers were only human. With brains kept in a state of excitement during the entire day, no wonder their nervous systems became unstrung. Their only chance of refreshment was during an occasional rush to the bun and sandwich stand in the lobby, though sometimes even that resource failed them. Then, with mind and body jaded—probably after undergoing a series of consultations upon many bills after the rising of the committees—the exhausted engineers would seek to stimulate nature by a late, perhaps a heavy dinner. What chance had any ordinary constitution of surviving such an ordeal? The consequence was, that stomach, brain, and liver were alike injured, and hence the men who bore the heat and brunt of those struggles—Stephenson, Brunel, Locke, and Errington—have already all died, comparatively young men.

In mentioning the name of Brunel, we are reminded of him as the principal rival and competitor of Robert Stephenson. Both were the sons of distinguished men, and both inherited the fame and followed in the footsteps of their fathers. The Stephensons were inventive, practical, and sagacious; the Brunels ingenious, imaginative, and daring. The former were as thoroughly English in their characteristics as the latter perhaps were as thoroughly French. The fathers and the sons were alike successful in their works, though not in the same degree. Measured by practical and profitable results, the Stephensons were unquestionably the safer men to follow.

Robert Stephenson and Isambard Kingdom Brunel were destined often to come into collision in the course of their professional life. Their respective railway districts "marched" with each other, and it became their business to invade or defend those districts, according as the policy of their respective boards might direct. The gauge of 7 feet fixed by Brunel for the Great Western Railway, so entirely different from that of 4 feet 8-1/2 inches adopted by the Stephensons on the Northern and Midland lines,[86] was from the first a great cause of contention. But Brunel had always an aversion to follow any man's lead; and that another engineer had fixed the gauge of a railway, or built a bridge, or designed an engine in one way, was of itself often a sufficient reason with him for adopting an altogether different course. Robert Stephenson, on his part, though less bold, was more practical, preferring to follow the old routes, and to tread in the safe steps of his father.

Mr. Brunel, however, determined that the Great Western should be a giant's road, and that traveling should be conducted upon it at double speed. His ambition was to make the best road that imagination could devise, whereas the main object of the Stephensons, both father and son, was to make a road that would pay. Although, tried by the Stephenson test, Brunel's magnificent road was a failure so far as the shareholders in the Great Western Company were concerned, the stimulus which his ambitious designs gave to mechanical invention at the time proved a general good. The narrow-gauge engineers exerted themselves to quicken their locomotives to the utmost. They improved and reimproved them. The machinery was simplified and perfected. Outside cylinders gave place to inside; the steadier and more rapid and effective action of the engine was secured, and in a few years the highest speed on railways went up from thirty to about fifty miles an hour. For this rapidity in progress we are in no small degree indebted to the stimulus imparted to the narrow-gauge engineers by Mr. Brunel.

It was one of the characteristics of Brunel to believe in the success of the schemes for which he was professionally engaged as engineer, and he proved this by investing his savings largely in the Great Western Railway, in the South Devon Atmospherical line, and in the Great Eastern steam-ship, with what results are well known. Robert Stephenson, on the contrary, with characteristic caution, toward the latter years of his life avoided holding unguaranteed railway shares; and though he might execute magnificent structures, such as the Victoria Bridge across the St. Lawrence, he was careful not to embark any portion of his own fortune in the ordinary capital of these concerns. In 1845 he shrewdly foresaw the inevitable crash that was about to succeed the mania of that year, and while shares were still at a premium he took the opportunity of selling out all that he held. He urged his father to do the same thing, but George's reply was characteristic. "No," said he "I took my shares for an investment, and not to speculate with, and I am not going to sell them now because people have gone mad about railways." The consequence was, that he continued to hold the £60,000 which he had invested in the shares of various railways until his death, when they were at once sold out by his son, though at a great depreciation on their original cost.

One of the hardest battles fought between the Stephensons and Brunel was for the railway between Newcastle and Berwick, forming part of the great East Coast route to Scotland. As early as 1836 George Stephenson had surveyed two lines to connect Edinburg with Newcastle: one by Berwick and Dunbar along the coast, and the other, more inland, by Carter Fell, up the vale of the Gala, to the northern capital. Two years later he made a farther examination of the intervening country, and reported in favor of the coast line. The inland route, however, was not without its advocates. But both projects lay dormant for several years longer, until the completion of the Midland and other main lines as far north as Newcastle had the effect of again reviving the subject of the extension of the route as far as Edinburg.

On the 18th of June, 1844, the Newcastle and Darlington line—an important link of the great main highway to the north—was completed and publicly opened, thus connecting the Thames and the Tyne by a continuous line of railway. On that day George Stephenson and a distinguished party of railway men traveled by express train from London to Newcastle in about nine hours. It was a great event, and was worthily celebrated. The population of Newcastle held holiday; and a banquet given in the Assembly Rooms the same evening assumed the form of an ovation to Mr. Stephenson and his son.

After the opening of this railway, the project of the East Coast line from Newcastle to Berwick was revived, and George Stephenson, who had already identified himself with the question, and was intimately acquainted with every foot of the ground, was again called upon to assist the promoters with his judgment and experience. He again recommended as strongly as before the line he had previously surveyed; and on its being adopted by the local committee, the necessary steps were taken to have the scheme brought before Parliament in the ensuing session. The East Coast line was not, however, to be allowed to pass without a fight. On the contrary, it had to encounter as stout an opposition as Stephenson had ever experienced.

We have already stated that about this time the plan of substituting atmospheric pressure for locomotive steam-power in the working of railways had become very popular. Many eminent engineers avowedly supported atmospheric in preference to locomotive lines; and many members of Parliament, headed by the prime ministers, were strongly disposed in their favor. Mr. Brunel warmly espoused the atmospheric principle, and his persuasive manner, as well as his admitted scientific ability, unquestionably exercised considerable influence in determining the views of many leading members of both houses. Among others, Lord Howick, one of the members for Northumberland, advocated the new principle, and, possessing great local influence, he succeeded in forming a powerful confederacy of the landed gentry in favor of Brunel's atmospheric railway through the country.

George Stephenson could not brook the idea of seeing the locomotive, for which he had fought so many stout battles, pushed to one side, and that in the very county in which its great powers had been first developed. Nor did he relish the appearance of Mr. Brunel as the engineer of Lord Howick's scheme, in opposition to the line which had occupied his thoughts and been the object of his strenuous advocacy for so many years. When Stephenson first met Brunel in Newcastle, he good-naturedly shook him by the collar, and asked "what business he had north of the Tyne?" George gave him to understand that they were to have a fair stand-up fight for the ground, and shaking hands before the battle like Englishmen, they parted in good-humor. A public meeting was held at Newcastle in the following December, when, after a full discussion of the merits of the respective plans, Stephenson's line was almost unanimously adopted as the best.

The rival projects went before Parliament in 1845, and a severe contest ensued. The display of ability and tactics on both sides was great. Robert Stephenson was examined at great length as to the merits of the locomotive line, and Brunel at equally great length as to the merits of the atmospheric. Mr. Brunel, in his evidence, said that, after numerous experiments, he had arrived at the conclusion that the mechanical contrivance of the atmospheric system was perfectly applicable, and he believed that it would likewise be more economical in most cases than locomotive power. "In short," said he, "rapidity, comfort, safety, and economy are its chief recommendations."

Notwithstanding the promise of Mr. Sergeant Wrangham, the counsel for Lord Howick's scheme, that the Northumberland atmospheric was to be "a respectable line, and not one that was to be converted into a road for the accommodation of the coal-owners of the district," the locomotive again triumphed. The Stephenson Coast line secured the approval of Parliament, and the shareholders in the Atmospheric Company were happily prevented investing their capital in what would unquestionably have proved a gigantic blunder. For, less than three years later, the whole of the atmospheric tubes which had been laid down on other lines were pulled up and the materials sold, including Mr. Brunel's immense tube on the South Devon Railway[87]—to make way for the working of the locomotive engine. George Stephenson's first verdict of "It won't do" was thus conclusively confirmed.

Robert Stephenson used afterward to describe with gusto an interview which took place between Lord Howick and his father, at his office in Great George Street, during the progress of the bill in Parliament. His father was in the outer office, where he used to spend a good deal of his spare time, occasionally taking a quiet wrestle with a friend when nothing else was stirring.[88] On the day in question, George was standing with his back to the fire, when Lord Howick called to see Robert. Oh! thought George, he has come to try and talk Robert over about that atmospheric gimcrack; but I'll tackle his lordship. "Come in, my lord," said he; "Robert's busy; but I'll answer your purpose quite as well; sit down here, if you please." George began, "Now, my lord, I know very well what you have come about: it's that atmospheric line in the North; I will show you in less than five minutes that it can never answer." "If Mr. Robert Stephenson is not at liberty, I can call again," said his lordship. "He's certainly occupied on important business just at present," was George's answer, "but I can tell you far better than he can what nonsense the atmospheric system is: Robert's good-natured, you see, and if your lordship were to get alongside of him you might talk him over; so you have been quite lucky in meeting with me. Now just look at the question of expense," and then he proceeded in his strong Doric to explain his views in detail, until Lord Howick could stand it no longer, and he rose and walked toward the door. George followed him down stairs to finish his demolition of the atmospheric system, and his parting words were, "You may take my word for it, my lord, it will never answer." George afterward told his son with glee of "the settler" he had given Lord Howick.

So closely were the Stephensons identified with this measure, and so great was the personal interest which they were both known to take in its success, that, on the news of the passing of the bill reaching Newcastle, a sort of general holiday took place, and the workmen belonging to the Stephenson Locomotive Factory, upward of eight hundred in number, walked in procession through the principal streets of the town, accompanied by music and banners.

It is unnecessary to enter into any description of the works of the Newcastle and Berwick Railway. There are no fewer than a hundred and ten bridges of all sorts on the line—some under and some over it—the viaducts over the Ouseburn, the Wansbeck, and the Coquet being of considerable importance. But by far the most formidable piece of masonry work on this railway is at its northern extremity, where it passes across the Tweed into Scotland, immediately opposite the formerly redoubtable castle of Berwick. Not many centuries had passed since the district amid which this bridge stands was the scene of almost constant warfare. Berwick was regarded as the key of Scotland, and was fiercely fought for, being sometimes held by a Scotch and sometimes by an English garrison. Though strongly fortified, it was repeatedly taken by assault. On its capture by Edward I., Boetius says, 17,000 persons were slain, so that its streets "ran with blood like a river." Within sight of the ramparts, a little to the west, is Halidon Hill, where a famous victory was gained by Edward III. over the Scottish army under Douglas; and there is scarcely a foot of ground in the neighborhood but has been the scene of contention in days long past. In the reigns of James I. and Charles I., a bridge of fifteen arches was built across the Tweed at Berwick; and now a railway bridge of twenty-eight arches was built a little above the old one, but at a much higher level. The bridge built by the kings out of the national resources cost £15,000, and occupied twenty-four years and four months in the building; the bridge built by the Railway Company, with funds drawn from private resources, cost £120,000, and was finished in three years and four months from the day of laying the foundation stone.

This important viaduct, built after the designs of Robert Stephenson, consists of a series of twenty-eight semicircular arches, each 61 feet 6 inches in span, the greatest height above the bed of the river being 126 feet. The whole is built of ashlar, with a hearting of rubble, excepting the river parts of the arches, which are constructed with bricks laid in cement. The total length of the work is 2160 feet. The foundations of the piers were got in by coffer-dams in the ordinary way, Nasmyth's steam-hammer being extensively used in driving the piles. The bearing piles, from which the foundations of the piers were built up, were each capable of carrying 70 tons.

Another bridge, of still greater importance, necessary to complete the continuity of the East Coast route, was the master-work erected by Robert Stephenson between the north and south banks of the Tyne, at Newcastle, commonly known as the High-Level Bridge. Mr. R. W. Brandling, George Stephenson's early friend, is entitled to the merit of originating the idea of this bridge, as it was eventually carried out, with a central terminus for the northern railways in the Castle Garth. The plan was first promulgated by him in 1841; and in the following year it was resolved that George Stephenson should be consulted as to the most advisable site for the proposed structure. A prospectus of a High-Level Bridge Company was issued in 1843, the names of George Stephenson and George Hudson appearing on the committee of management, Robert Stephenson being the consulting engineer. The project was eventually taken up by the Newcastle and Darlington Railway Company, and an act for the construction of the bridge was obtained in 1845.

The rapid extension of railways had given an extraordinary stimulus to the art of bridge-building; the number of such structures erected in Great Britain alone, since 1830, having been above thirty thousand, or far more than all that previously existed in the country. Instead of the erection of a single large bridge constituting, as formerly, an epoch in engineering, hundreds of extensive bridges of novel design were simultaneously constructed. The necessity which existed for carrying rigid roads, capable of bearing heavy railway trains at high speed, over extensive gaps free of support, rendered it apparent that the methods which had up to that time been employed for bridging space were altogether insufficient. The railway engineer could not, like the ordinary road engineer, divert his road, and make choice of the best point for crossing a river or a valley. He must take such ground as lay in the line of his railway, be it bog, or mud, or shifting sand. Navigable rivers and crowded thoroughfares had to be crossed without interruption to the existing traffic, sometimes by bridges at right angles to the river or road, sometimes by arches more or less oblique. In many cases great difficulty arose from the limited nature of the headway; but, as the level of the original road must generally be preserved, and that of the railway was in a measure fixed and determined, it was necessary to modify the form and structure of the bridge in almost every case, in order to comply with the public requirements. Novel conditions were met by fresh inventions, and difficulties of an unusual character were one after another successfully surmounted. In executing these extraordinary works, iron has been throughout the sheet-anchor of the engineer. In the various forms of cast and wrought iron it offered a valuable resource where rapidity of execution, great strength and cheapness of construction in the first instance were elements of prime importance, and by its skillful use the railway architect was enabled to achieve results which thirty years since would scarcely have been thought possible.

In many of the early cast-iron bridges the old form of the arch was adopted, the stability of the structure depending wholly on compression, the only novel feature consisting in the use of iron instead of stone. But in a large proportion of cases, the arch, with the railroad over it, was found inapplicable in consequence of the limited headway which it provided. Hence it early occurred to George Stephenson, when constructing the Liverpool and Manchester Railway, to adopt the simple cast-iron beam for the crossing of several roads and canals along that line—this beam resembling in some measure the lintel of the early temples—the pressure on the abutments being purely vertical. One of the earliest instances of this kind of bridge was that erected over Water Street, Manchester, in 1829; after which, cast-iron girders, with their lower webs considerably larger than their upper, were ordinarily employed where the span was moderate, and wrought-iron tie-rods below were added to give increased strength where the span was greater.

The next step was the contrivance of arched beams or bow-string girders, firmly held together by horizontal ties to resist the thrust, instead of abutments. Numerous excellent specimens of this description of bridge were erected by Robert Stephenson on the original London and Birmingham Railway; but by far the grandest work of the kind—perfect as a specimen of modern constructive skill—was the High-Level Bridge, which we owe to the genius of the same engineer.

The problem was to throw a railway bridge across the deep ravine which lies between the towns of Newcastle and Gateshead, at the bottom of which flows the navigable river Tyne. Along and up the sides of the valley—on the Newcastle bank especially—run streets of old-fashioned houses, clustered together in the strange forms peculiar to the older cities. The ravine is of great depth—so deep and gloomy-looking toward dusk, that local tradition records that when the Duke of Cumberland arrived late in the evening, at the brow of the hill overlooking the Tyne, on his way to Culloden, he exclaimed to his attendants, on looking down into the black gorge before him, "For God's sake, don't think of taking me down that coal-pit at this time of night!" The road down the Gateshead High Street is almost as steep as the roof of a house, and up the Newcastle Side, as the street there is called, it is little better. During many centuries the traffic north and south passed along this dangerous and difficult route, across the old bridge which spans the river in the bottom of the valley. For some thirty years the Newcastle Corporation had discussed various methods of improving the communication between the towns; and the discussion might have gone on for thirty years more, but for the advent of railways, when the skill and enterprise to which they gave birth speedily solved the difficulty and bridged the ravine. The local authorities adroitly took advantage of the opportunity, and insisted on the provision of a road for ordinary vehicles and foot passengers in addition to the railroad. In this circumstance originated one of the most remarkable peculiarities of the High-Level Bridge, which serves two purposes, being a railway above, with a carriage roadway underneath.

The breadth of the river at the point of crossing is 515 feet, but the length of the bridge and viaduct between the Gateshead station and the terminus on the Newcastle side is about 4000 feet. It springs from Pipewell Gate Bank, on the south, directly across to Castle Garth, where, nearly fronting the bridge, stands the fine old Norman keep of the New Castle, now nearly eight hundred years old; and a little beyond it is the spire of St. Nicholas Church, with its light and graceful Gothic crown, the whole forming a grand architectural group of unusual historic interest. The bridge passes completely over the roofs of the houses which fill both sides of the valley, and the extraordinary height of the upper parapet, which is about 130 feet above the bed of the river, offers a prospect to the passing traveler the like of which is perhaps nowhere else to be seen. Far below lie the queer chares and closes, the wynds and lanes of old Newcastle; the water is crowded with pudgy, black coal keels; and, when there is a lull in the great clouds of smoke which usually obscure the sky, the funnels of steamers and the masts of the shipping may be seen far down the river. The old bridge lies so far beneath that the passengers crossing it seem like so many bees passing to and fro.

The first difficulty encountered in building the bridge was in securing a solid foundation for the piers. The dimensions of the piles to be driven were so huge that the engineer found it necessary to employ some extraordinary means for the purpose. He called Nasmyth's Titanic steam-hammer to his aid—the first occasion, we believe, on which this prodigious power was employed in bridge pile-driving. A temporary staging was erected for the steam-engine and hammer apparatus, which rested on two keels, and, notwithstanding the newness and stiffness of the machinery, the first pile was driven on the 6th of October, 1846, to a depth of 32 feet in four minutes. Two hammers of 30 cwt. each were kept in regular use, making from 60 to 70 strokes per minute, and the results were astounding to those who had been accustomed to the old style of pile-driving by means of the ordinary pile-frame, consisting of slide, ram, and monkey. By the old system the pile was driven by a comparatively small mass of iron descending with great velocity from a considerable height—the velocity being in excess and the mass deficient, and calculated, like the momentum of a cannon-ball, rather for destructive than impulsive action. In the case of the steam pile-driver, on the contrary, the whole weight of a heavy mass is delivered rapidly upon a driving-block of several tons weight placed directly over the head of the pile, the weight never ceasing, and the blows being repeated at the rate of a blow a second, until the pile is driven home. It is a curious fact, that the rapid strokes of the steam-hammer evolved so much heat, that on many occasions the pile-head burst into flame during the process of driving. The elastic force of steam is the power that lifts the ram, the escape permitting its entire force to fall upon the head of the driving-block; while the steam above the piston on the upper part of the cylinder, acting as a buffer or recoil-spring, materially enhances the effect of the downward blow. As soon as one pile was driven, the traveler, hovering overhead, presented another, and down it went into the solid bed of the river with almost as much ease as a lady sticks pins into a cushion. By the aid of this formidable machine, what before was among the most costly and tedious of engineering operations was rendered simple, easy, and economical.

When the piles had been driven and the coffer-dams formed and puddled, the water within the inclosed spaces was pumped out by the aid of powerful engines, so as to lay bare the bed of the river. Considerable difficulty was experienced in getting in the foundations of the middle pier, in consequence of the water forcing itself through the quicksand beneath as fast as it was removed. This fruitless labor went on for months, and many expedients were tried. Chalk was thrown in in large quantities outside the piling, but without effect. Cement concrete was at last put within the coffer-dam until it set, and the bottom was then found to be secure. A bed of concrete was laid up to the level of the heads of the piles, the foundation course of stone blocks being commenced about two feet below low water, and the building proceeded without farther difficulty. It may serve to give an idea of the magnitude of the work when we state that 400,000 cubic feet of ashlar, rubble, and concrete were worked up in the piers, and 450,000 cubic feet in the land-arches and approaches.

The most novel feature of the structure is the use of cast and wrought iron in forming the double bridge, which admirably combines the two principles of the arch and suspension, the railway being carried over the back of the ribbed arches in the usual manner, while the carriage-road and footpaths, forming a long gallery or aisle, are suspended from these arches by wrought-iron vertical rods, with horizontal tie-bars to resist the thrust. The suspension-bolts are inclosed within spandril pillars of cast iron, which give great stiffness to the superstructure. This system of longitudinal and vertical bracing has been much admired, for it not only accomplishes the primary object of securing rigidity in the roadway, but at the same time, by its graceful arrangement, heightens the beauty of the structure. The arches consist of four main ribs, disposed in pairs, with a clear distance between the two inner arches of 20 feet 4 inches, forming the carriage-road, while between each of the inner and outer ribs there is a space of 6 feet 2 inches, constituting the footpaths. Each arch is cast in five separate lengths or segments, strongly bolted together. The ribs spring from horizontal plates of cast iron, bedded and secured on the stone piers. All the abutting joints were carefully executed by machinery, the fitting being of the most perfect kind. In order to provide for the expansion and contraction of the iron arching, and to preserve the equilibrium of the piers without disturbance or racking of the other parts of the bridge, it was arranged that the ribs of every two adjoining arches resting on the same pier should be secured to the springing-plates by keys and joggles; while on the next piers, on either side, the ribs remained free, and were at liberty to expand or contract according to temperature—a space being left for the purpose. Hence each arch is complete and independent in itself, the piers having simply to sustain their vertical pressure. The arches are six in number, of 125 feet span each, the two approaches to the bridge being formed of cast-iron pillars and bearers in keeping with the arches.

The result is a bridge that for massive solidity may be pronounced unrivaled. It is one of the most magnificent and striking of the bridges to which railways have given birth, and has been worthily styled "the King of railway structures." It is a monument of the highest engineering skill of our time, with the impress of power grandly stamped upon it. It will also be observed from the drawing placed as the frontispiece to this Life, that the High-Level Bridge forms a very fine object in a picture of great interest, full of striking architectural variety and beauty. The bridge was opened on the 15th of August, 1849. A few days after, the royal train passed over it, halting for a few minutes to enable her majesty to survey the wonderful scene below. In the course of the following year the queen opened the extensive stone viaduct across the Tweed above described, by which the last link was completed of the continuous line of railway between London and Edinburg. Over the entrance to the Berwick station, occupying the site of the once redoubtable Border fortress, so often the deadly battle-ground of the ancient Scots and English, was erected an arch under which the royal train passed, bearing in large letters of gold the appropriate words, "The last act of the Union."

The warders at Berwick no longer look out from the castle walls to descry the glitter of Southron spears. The bell-tower, from which the alarm was sounded of old, though still standing, is deserted; the only bell heard within the precincts of the old castle being the railway porter's bell announcing the arrival and departure of trains. You see the Scotch Express pass along the bridge and speed southward on the wings of steam. But no alarm spreads along the Border now. Northumbrian beeves are safe. Chevy Chase and Otterburn are quiet sheep-pastures. The only men-at-arms on the battlements of Alnwick Castle are of stone. Bamborough Castle has become an asylum for shipwrecked mariners, and the Norman Keep at Newcastle has been converted into a Museum of Antiquities. The railway has indeed consummated the Union.

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CHAPTER XVIII.

CHESTER AND HOLYHEAD RAILWAY—MENAI AND CONWAY BRIDGES.

We have now to describe briefly another great undertaking, begun by George Stephenson, and taken up and completed by his son, in the course of which the latter carried out some of his greatest works—we mean the Chester and Holyhead Railway, completing the railway connection with Dublin, as the Newcastle and Berwick line completed the connection with Edinburg. It will thus be seen how closely Telford was followed by the Stephensons in perfecting the highways of their respective epochs; the former by means of turnpike roads, and the latter by means of railways.

George Stephenson surveyed a line from Chester to Holyhead in 1838, and at the same time reported on the line through North Wales to Port Dynallen, as proposed by the Irish Railway Commissioners. His advice was strongly in favor of adopting the line to Holyhead, as less costly and presenting better gradients. A public meeting was held at Chester in January, 1839, in support of the latter measure, at which he was present to give explanations. Mr. Uniacke, the mayor, in opening the proceedings, observed that it clearly appeared that the rival line through Shrewsbury was quite impracticable. Mr. Stephenson, he added, was present in the room, ready to answer any questions which might be put to him on the subject; and "it would be better that he should be asked questions than required to make a speech; for, though a very good engineer, he was a bad speaker."

One of the questions then put to Mr. Stephenson related to the mode by which he proposed to haul the passenger-carriages over the Menai Suspension Bridge by horse-power; and he was asked whether he knew the pressure the bridge was capable of sustaining. His answer was that "he had not yet made any calculations, but he proposed getting data which would enable him to arrive at an accurate calculation of the actual strain upon the bridge during the late gale. He had, however, no hesitation in saying that it was more than twenty times as much as the strain of a train of carriages and a locomotive engine. The only reason why he proposed to convey the carriages over by horses was in order that he might, by distributing the weight, not increase the wavy motion. All the train would be on at once, but distributed. This he thought better than passing them linked together, by a locomotive engine." It will thus be observed that the practicability of throwing a rigid railroad bridge across the Straits had not yet been completed.

The Dublin Chamber of Commerce passed resolutions in favor of Stephenson's line after hearing his explanations of its essential features. The project, after undergoing much discussion, was at length embodied in an act passed in 1844, and the work was brought to a successful completion by his son, with several important modifications, including the grand original feature of the tubular bridges across the Menai Straits and the estuary of the Conway. Excepting these great works, the construction of this line presented no unusual features, though the remarkable terrace cut for the accommodation of the railway under the steep slope of Penmaen Mawr is worthy of a passing notice.

About midway between Conway and Bangor, Penmaen Mawr forms a bold and almost precipitous headland, at the base of which, in rough weather, the ocean dashes with great fury. There was not space enough between the mountain and the strand for the passage of the railway; hence in some places the rock had to be blasted to form a terrace, and in others sea walls had to be built up to the proper level, on which to form an embankment of sufficient width to enable the road to be laid. A tunnel of 10-1/2 chains in length was cut through the headland itself; and on its east and west sides the line was formed by a terrace cut out of the cliff, and by embankments protected by sea walls, the terrace being three times interrupted by embankments in its course of about a mile and a quarter. The road lies so close under the steep mountain face that it was even found necessary at certain places to protect it against possible accidents from falling stones, by means of a covered way. The terrace on the east side of the headland was, however, in some measure, protected against the roll of the sea by the mass of stone run out from the tunnel, which formed a deep shingle-bank in front of the wall.

The part of the work which lies to the westward of the headland penetrated by the tunnel was exposed to the full force of the sea, and the formation of the road at that point was attended with great difficulty. While the sea wall was still in progress, its strength was severely tried by a strong northwesterly gale which blew in October, 1846, accompanied with a spring tide of 17 feet. On the following morning it was found that a large portion of the rubble was irreparably injured, and 200 yards of the wall were then replaced by an open viaduct, with the piers placed edgeways to the sea, the openings between them being spanned by ten cast-iron girders 42 feet long. This accident farther induced the engineer to alter the contour of the sea wall, so that it should present a diminished resistance to the force of the waves.

But the sea repeated its assaults, and made farther havoc with the work, entailing heavy expenses and a complete reorganization of the contract. Increased solidity was then given to the masonry, and the face of the wall underwent farther change. At some points outworks were constructed, and piles were driven into the beach about 15 feet from the base of the wall for the purpose of protecting its foundations and breaking the force of the waves. The work was at length finished after about three years' anxious labor; but Mr. Stephenson confessed that if a long tunnel had been made in the first instance through the solid rock of Penmaen Mawr, a saving of from £25,000 to £30,000 would have been effected. He also said he had arrived at the conclusion that in railway works engineers should endeavor as far as possible to avoid the necessity of contending with the sea;[89] but if he were ever again compelled to go within its reach, he would adopt, instead of retaining walls, an open viaduct, placing all the piers edgeways to the force of the sea, and allowing the waves to break upon a natural slope of beach. He was ready enough to admit the errors he had committed in the original design of this work; but he said he had always gained more information from studying the causes of failures and endeavoring to surmount them, than he had done from easily-won successes. While many of the latter had been forgotten, the former were indelibly fixed in his memory.

But by far the greatest difficulty which Robert Stephenson had to encounter in executing this railway was in carrying it across the Straits of Menai and the estuary of the Conway, where, like his predecessor Telford, when forming his high road through North Wales, he was under the necessity of resorting to new and altogether untried methods of bridge construction. At Menai, the waters of the Irish Sea are perpetually vibrating along the precipitous shores of the Strait, rising and falling from 20 to 25 feet at each successive tide, the width and depth of the channel being such as to render it available for navigation by the largest ships. The problem was to throw a bridge across this wide chasm—a bridge of unusual span and dimensions—of such strength as to be capable of bearing the heaviest loads at high speeds, and of such a uniform height throughout as not in any way to interfere with the navigation of the Strait. From an early period Mr. Stephenson had fixed upon the spot where the Britannia Rock occurs, nearly in the middle of the channel, as the most eligible point for crossing, the water width from shore to shore at high water being there about 1100 feet.

The engineer's first idea was to construct the bridge of two cast-iron arches of 350 feet span each. There was no novelty in this idea; for, as early as the year 1801, Mr. Rennie prepared a design of a cast-iron bridge across the Strait at the Swilly Rocks, the great centre arch of which was to be 450 feet span; and at a later period, in 1810, Telford submitted a design of a similar bridge at Inys-y-Moch, with a single cast-iron arch of 500 feet. But the same objections which led to the rejection of Rennie's and Telford's designs proved fatal to Robert Stephenson's, and his iron-arched railway bridge was rejected by the Admiralty. The navigation of the Strait was under no circumstances to be interfered with; and even the erection of scaffolding from below, to support the bridge during construction, was not to be permitted. The idea of a suspension bridge was dismissed as inapplicable, a degree of rigidity and strength greater than could be secured by any bridge erected on the principle of suspension being considered an indispensable condition of the proposed structure.

Mr. Stephenson next considered the expediency of erecting a bridge by means of suspended centering, after the ingenious method proposed by Telford in 1810,[90] by which the arching was to be carried out by placing equal and corresponding voussoirs on opposite sides of the pier at the same time, tying them together by horizontal tie-bolts. The arching, thus extended outward from each pier and held in equilibrium, would have been connected at the crown with the extremity of the arch advanced in like manner from the adjoining pier. It was, however, found that this method of construction was not applicable at the crossing of the Conway, and it was eventually abandoned. Various other plans were suggested; but the whole question remained unsettled even down to the time when the company went before Parliament in 1844 for power to construct the proposed bridges. No existing kind of structure seemed to be capable of bearing the severe extension to which rigid bridges of the necessary spans would be subjected, and some new expedient of engineering therefore became necessary.

Mr. Stephenson was then led to reconsider a design which he had made in 1841 for a road bridge over the River Lea at Ware, with a span of 50 feet, the conditions only admitting of a platform 18 or 20 inches thick. For this purpose a wrought-iron platform was devised, consisting of a series of simple cells, formed of boiler-plates riveted together with angle-iron. The bridge was not, however, carried out after this design, but was made of separate wrought-iron girders composed of riveted plates.[91] Recurring to his first idea of this bridge, the engineer thought that a stiff platform might be constructed, with sides of strongly-trussed frame-work of wrought iron, braced together at top and bottom with plates of like material riveted together with angle-iron, after a method adopted by Mr. Rendel in stiffening the suspension bridge at Montrose with wooden trellis-work a few years before; and that such platform might be suspended by strong chains on either side to give it increased security. "It was now," says Mr. Stephenson, "that I came to regard the tubular platform as a beam, and that the chains should be looked upon as auxiliaries." It appeared to him, nevertheless, that without a system of diagonal struts inside, which of course would have prevented the passage of trains through it, this kind of structure was ill suited for maintaining its form, and would be very liable to become lozenge-shaped. Besides, the rectangular figure was deemed objectionable, from the large surface which it presented to the wind.

It then occurred to him that circular or elliptical tubes might better answer the intended purpose; and in March, 1845, he gave instructions to two of his assistants to prepare drawings of such a structure, the tubes being made with a double thickness of plate at top and bottom. The results of the calculations made as to the strength of such a tube were considered so satisfactory, that Mr. Stephenson says he determined to fall back upon a bridge of this description on the rejection of his design of the two cast-iron arches by the Parliamentary Committee. Indeed, it became evident that a tubular wrought-iron beam was the only structure which combined the necessary strength and stability for a railway, with the conditions deemed essential for the protection of the navigation:

Mr. Stephenson accordingly announced to the directors of the railway that he was prepared to carry out a bridge of this general description, and they adopted his views, though not without considerable misgivings.

While the engineer's mind was still occupied with the subject, an accident occurred to the Prince of Wales iron steam-ship, at Blackwall, which singularly corroborated his views as to the strength of wrought-iron beams of large dimensions. When this vessel was being launched, the cleat on the bow gave way in consequence of the bolts breaking, and let the vessel down so that the bilge came in contact with the wharf, and she remained suspended between the water and the wharf for a length of about 110 feet, but without any injury to the plates of the ship, satisfactorily proving the great strength of this form of construction. Thus Mr. Stephenson became gradually confirmed in his opinion that the most feasible method of bridging the strait at Menai and the river at Conway was by means of a hollow tube of wrought iron. As the time was approaching for giving evidence before Parliament on the subject, it was necessary for him to settle some definite plan for submission to the committee.

The date of this consultation was early in April, 1845, and Mr. Fairbairn states that, on that occasion,

Mr. Fairbairn then proceeded to construct a number of experimental models, for the purpose of testing the strength of tubes of different forms. The short period which elapsed, however, before the bill was in committee, did not admit of much progress being made with those experiments; but from the evidence in chief given by Mr. Stephenson on the subject on the 5th of May following, it appears that the idea which prevailed in his mind was that of a bridge with openings of 450 feet (afterward increased to 460 feet), with a roadway formed of a hollow wrought-iron beam about 25 feet in diameter, presenting a rigid platform suspended by chains. At the same time, he expressed the confident opinion that a tube of wrought iron would possess sufficient strength and rigidity to support a railway train running inside of it without the help of the chains.

While the bill was still in progress, Mr. Fairbairn proceeded with his experiments. He first tested tubes of a cylindrical form, in consequence of the favorable opinion entertained by Mr. Stephenson of tubes in that shape, extending them subsequently to those of an elliptical form.[95] He found tubes thus shaped more or less defective, and proceeded to test those of a rectangular kind. After the bill had received the royal assent, on the 30th of June, 1845, the directors of the company, with great liberality, voted a sum for the purpose of enabling the experiments to be prosecuted, and upward of £6000 were thus expended to make the assurance of their engineer doubly sure.

Mr. Fairbairn's tests were of the most elaborate and eventually conclusive character, bringing to light many new and important facts of great practical value. The due proportions and thicknesses of the top, bottom, and sides of the tubes were arrived at after a vast number of separate trials, one of the results of the experiments being the adoption of Mr. Fairbairn's invention of rectangular hollow cells in the top of the beam for the purpose of giving it the requisite degree of strength. About the end of August it was thought desirable to obtain the assistance of a mathematician, who should prepare a formula by which the strength of a full-sized tube might be calculated from the results of the experiments made with tubes of smaller dimensions. Professor Hodgkinson was accordingly called in, and he proceeded to verify and confirm the experiments which Mr. Fairbairn had made, and afterward reduced them to the required formulæ, though Mr. Fairbairn states that they did not appear in time to be of any practical service in proportioning the parts of the largest tubes.[96]

Mr. Stephenson's time was so much engrossed with his extensive engineering business that he was in a great measure precluded from devoting himself to the consideration of the practical details, which he felt were safe in the hands of Mr. Fairbairn—"a gentleman," as he stated to the Committee of the Commons, "whose experience was greater than that of any other man in England." The results of the experiments were communicated to him from time to time, and were regarded by him as exceedingly satisfactory. It would appear, however, that while Mr. Fairbairn urged the sufficient rigidity and strength of the tubes without the aid of chains, Mr. Stephenson had not quite made up his mind upon the point. Mr. Hodgkinson, also, was strongly inclined to retain them.[97] Mr. Fairbairn held that it was quite practicable to make the tubes "sufficiently strong to sustain not only their own weight, but, in addition to that load, 2000 tons equally distributed over the surface of the platform—a load ten times greater than they will ever be called upon to support."

It was thoroughly characteristic of Mr. Stephenson, and of the caution with which he proceeded in every step of this great undertaking—probing every inch of the ground before he set his foot down upon it—that he should, early in 1846, have appointed his able assistant, Mr. Edwin Clark, to scrutinize carefully the results of every experiment, whether made by Mr. Fairbairn or Mr. Hodgkinson, and subject them to a separate and independent analysis before finally deciding upon the form or dimensions of the structure, or upon any mode of procedure connected with it. That great progress had been made by the two chief experimenters before the end of 1846 appears from the papers on the subject read by Messrs. Fairbairn and Hodgkinson before the British Association at Southampton in September of that year. In the course of the following month Mr. Stephenson had become satisfied that the use of auxiliary chains was unnecessary, and that the tubular bridge might be made of such strength as to be entirely self-supporting.[98] While these important discussions were in progress, measures were taken to proceed with the masonry of the bridges simultaneously at Conway and the Menai Strait. The foundation-stone of the Britannia Bridge was laid by Mr. Frank Forster, the resident engineer, on the 10th of April, 1846; and on the 12th of May following that of the Conway Bridge was laid by Mr. A. M. Ross, resident engineer at that part of the works. Suitable platforms and workshops were also erected for proceeding with the punching, fitting, and riveting of the tubes; and when these operations were in full progress, the neighborhood of the Conway and Britannia Bridges presented scenes of extraordinary bustle and industry. On the 11th of July, 1847, Mr. Clark informed Mr. Stephenson that "the masonry gets on rapidly. The abutments on the Anglesea side resemble the foundations of a great city rather than of a single structure, and nothing appears to stand still here." About 1500 men were employed on the Britannia Bridge alone, and they mostly lived upon the ground in wooden cottages erected for the occasion. The iron plates were brought in ship-loads from Liverpool, Anglesea marble from Penmon, and red sandstone from Runcorn, in Cheshire, as wind and tide, and shipping and convenience, might determine. There was an unremitting clank of hammers, grinding of machinery, and blasting of rock going on from morning to night. In fitting the Britannia tubes together not less than 2,000,000 of bolts were riveted, weighing some 900 tons.

The Britannia Bridge consists of two independent continuous tubular beams, each 1511 feet in length, and each weighing 4680 tons, independent of the cast-iron frames inserted at their bearings on the masonry of the towers. These immense beams are supported at five places, namely, on the abutments and on three towers, the central of which is known as the Great Britannia Tower, 230 feet high, built on a rock in the middle of the Strait. The side towers are 18 feet less in height than the central one, and the abutments 35 feet lower than the side towers. The design of the masonry is such as to accord with the form of the tubes, being somewhat of an Egyptian character, massive and gigantic rather than beautiful, but bearing the unmistakable impress of power.

The bridge has four spans—two of 460 feet over the water, and two of 230 feet over the land. The weight of the longer spans, at the points where the tubes repose on the masonry, is not less than 1587 tons. On the centre tower the tubes lie solid; but on the land towers and abutments they lie on roller-beds, so as to allow of expansion and contraction. The road within each tube is 15 feet wide, and the height varies from 23 feet at the ends to 30 feet at the centre. To give an idea of the vast size of the tubes by comparison with other structures, it may be mentioned that each length constituting the main spans is twice as long as London Monument is high; and if it could be set on end in St. Paul's Church-yard, it would reach nearly 100 feet above the cross.

The Conway Bridge is, in most respects, similar to the Britannia, consisting of two tubes of 400 feet span, placed side by side, each weighing 1180 tons. The principle adopted in the construction of the tubes, and the mode of floating and raising them, was nearly the same as at the Britannia Bridge, though the general arrangement of the plates is in many respects different.

It was determined to construct the shorter outer tubes of the Britannia Bridge on scaffoldings in the positions in which they were permanently to remain, and to erect the larger tubes upon wooden platforms at high-water-mark on the Caernarvon shore, from whence they were to be floated in pontoons—in like manner as Rennie had floated into their places the centerings of his Waterloo and other bridges—and then raised into their proper places by means of hydraulic power, after a method originally suggested by Mr. Edwin Clark. The tubes of the Conway Bridge also were to be constructed on shore, and floated to their places on pontoons, as in the case of the main centre tubes of the Britannia Bridge.

The floating of these tubes on pontoons, from the places where they had been constructed to the recesses in the masonry of the towers, up which they were to be hoisted to the places they were permanently to occupy, was an anxious and exciting operation. The first proceeding of this nature was at Conway, where Mr. Stephenson directed it in person, assisted by Captain Claxton, Mr. Brunel, and other engineering friends. On the 6th of March, 1848, the pontoons bearing the first great tube of the up-line were floated round quietly and majestically into their place between the towers in about twenty minutes. Unfortunately, one of the sets of pontoons had become slightly slued by the stream, by which the Conway end of the tube was prevented from being brought home, and five anxious days to all concerned intervened before it could be set in its place. In the mean time, the presses and raising machinery had been fitted in the towers above, and the lifting process was begun on the 8th of April, when the immense mass was raised 8 feet, at the rate of about 2 inches a minute. On the 16th the tube had been raised and finally lowered into its permanent bed; the rails were laid within it; and on the 18th Mr. Stephenson passed through with the first locomotive. The second tube was proceeded with on the removal of the first from the platform, and was completed and floated in seven months. The rapidity with which this second tube was constructed was in no small degree owing to the Jacquard punching-machine, contrived for the purpose of punching the holes for the rivets by Mr. Roberts, of Manchester. The tube was finally fixed in its permanent bed on the 2d of January, 1849.

The floating and fixing of the great Britannia tubes was a still more formidable enterprise, though the experience gained at Conway rendered it easy compared with what it otherwise would have been. Mr. Stephenson superintended the operation of floating the first in person, giving the arranged signals from the top of the tube on which he was mounted, the active part of the business being performed by a numerous corps of sailors, under the immediate direction of Captain Claxton. Thousands of spectators lined the shores of the Strait on the evening of the 19th of June, 1849. On the land attachments being cut, the pontoons began to float off; but one of the capstans having given way from the too great strain put upon it, the tube was brought home again for the night. By next morning the defective capstan was restored, and all was in readiness for another trial. At half past seven in the evening the tube was afloat, and the pontoons swung out into the current like a monster pendulum, held steady by the shore guide-lines, but increasing in speed to almost a fearful extent as they neared their destined place between the piers.

By midnight all the pontoons had been got clear of the tube, which now hung suspended over the waters of the Strait by its two ends, which rested upon the edges cut in the rock for the purpose at the base of the Britannia and Anglesey towers respectively, up which the tube had now to be lifted by hydraulic power to its permanent place near the summit. The accuracy with which the gigantic beam had been constructed may be inferred from the fact that, after passing into its place, a clear space remained between the iron plating and the rock outside of it of only about three quarters of an inch!

Mr. Stephenson's anxiety was, of course, very great up to the time of effecting this perilous operation. When he had got the first tube floated at Conway and saw all safe, he said to Captain Moorsom, "Now I shall go to bed." But the Britannia Bridge was a still more difficult enterprise, and cost him many a sleepless night. Afterward describing his feelings to his friend Mr. Gooch, he said, "It was a most anxious and harassing time with me. Often at night I would lie tossing about, seeking sleep in vain. The tubes filled my head. I went to bed with them and got up with them. In the gray of the morning, when I looked across the Square,[100] it seemed an immense distance across to the houses on the opposite side. It was nearly the same length as the span of my tubular bridge!" When the first tube had been floated, a friend observed to him, "This great work has made you ten years older." "I have not slept sound," he replied, "for three weeks." Sir F. Head, however, relates that, when he revisited the spot on the following morning, he observed, sitting on a platform overlooking the suspended tube, a gentleman, reclining entirely by himself, smoking a cigar, and gazing, as if indolently, at the aerial gallery beneath him. It was the engineer himself, contemplating his newborn child. He had strolled down from the neighboring village, after his first sound and refreshing sleep for weeks, to behold in sunshine and solitude that which, during a weary period of gestation, had been either mysteriously moving in his brain, or, like a vision—sometimes of good omen and sometimes of evil—had, by night as well as by day, been flitting across his mind.

The next process was the lifting of the tube into its place, which was performed very deliberately and cautiously. It was raised by powerful hydraulic presses, only a few feet at a time, and carefully under-built, before being raised to a farther height. When it had been got up by successive stages of this kind to about 24 feet, an extraordinary accident occurred, during Mr. Stephenson's absence in London, which he afterward described to the author in as nearly as possible the following words: "In a work of such novelty and magnitude, you may readily imagine how anxious I was that every possible contingency should be provided for. Where one chain or rope was required, I provided two. I was not satisfied with 'enough:' I must have absolute security, so far as that was possible. I knew the consequences of failure would be most disastrous to the company, and that the wisest economy was to provide for all contingencies, at whatever cost. When the first tube at the Britannia had been successfully floated between the piers, ready for being raised, my young engineers were very much elated; and when the hoisting apparatus had been fixed, they wrote to me, saying, 'We are now all ready for raising her: we could do it in a day, or in two at the most.' But my reply was, No; you must only raise the tube inch by inch, and you must build up under it as you rise. Every inch must be made good. Nothing must be left to chance or good luck. And fortunate it was that I insisted upon this cautious course being pursued; for, one day, while the hydraulic presses were at work, the bottom of one of them burst clean away! The cross-head and the chains, weighing more than 50 tons, descended with a fearful crash upon the press, and the tube itself fell down upon the packing beneath. Though the fall of the tube was not more than nine inches, it crunched solid castings, weighing tons, as if they had been nuts. The tube itself was slightly strained and deflected, though it still remained sufficiently serviceable. But it was a tremendous test to which it was put, for a weight of upward of 5000 tons falling even a few inches must be admitted to be a very serious matter. That it stood so well was extraordinary. Clark immediately wrote me an account of the circumstance, in which he said, 'Thank God you have been so obstinate; for if this accident had occurred without a bed for the end of the tube to fall on, the whole would now have been lying across the bottom of the Straits.' Five thousand pounds extra expense was caused by this accident, slight though it might seem. But careful provision was made against future failure; a new and improved cylinder was provided; and the work was very soon advancing satisfactorily toward completion."[101]

When the queen first visited the Britannia Bridge, on her return from the North in 1852, Robert Stephenson accompanied her majesty and Prince Albert over the works, explaining the principles on which the bridge had been built, and the difficulties which had attended its erection. He conducted the royal party to near the margin of the sea, and, after describing to them the incident of the fall of the tube, and the reason of its preservation, he pointed with pardonable pride to a pile of stones which the workmen had there raised to commemorate the event. While nearly all the other marks of the work during its progress had been obliterated, that cairn had been left standing in commemoration of the caution and foresight of their chief.

The floating and raising of the remaining tubes need not be described in detail. The second was floated on the 3d of December, and set in its permanent place on the 7th of January, 1850. The others[102] were floated and raised in due course; on the 5th of March Mr. Stephenson put the last rivet in the tube, and passed through the completed bridge, accompanied by about a thousand persons, drawn by three locomotives. The bridge was found almost entirely rigid, scarcely showing the slightest deflection. When, in the course of the day, a train of 200 tons of coal was allowed to rest with all its weight, for two hours, in the centre of the eastern land tube, the deflection was only four tenths of an inch, or less than that produced upon the structure by half an hour's sunshine;[103] while the whole bridge might with safety, and without injury to itself, be deflected to the extent of 13 inches. The bridge was opened for public traffic on the 18th of March. The cost of the whole work was £234,450.

The Britannia Bridge is one of the most remarkable monuments of the enterprise and skill of the present century. Robert Stephenson was the master spirit of the undertaking. To him belongs the merit of first seizing the ideal conception of the structure best adapted to meet the necessities of the case, and of selecting the best men to work out his idea, himself watching, controlling, and testing every result by independent check and counter-check. And, finally, he organized and directed, through his assistants, the vast band of skilled workmen and laborers who were for so many years occupied in carrying his magnificent original conception to a successful practical issue.

But it was not accomplished without the greatest anxiety and mental pressure. Mr. Clark has well observed that few persons who merely witness the results of the engineer's labors can form any conception of the real difficulties overcome, and the intense anxiety involved in their elaboration. "If the stranger," he says, "who contemplates the finished reality, requires so much thought to appreciate its principles and comprehend its detail, what weary hours must he have undergone who first conceived its bold proportions—who, combating, almost alone, every prejudice that assailed him, and with untiring labor discussing every objection, listening to every opinion, and embodying every inquiry, at length matured, step by step, this noble monument?" On the occasion of raising the last tube into its place, Mr. Stephenson declared, in reply to the felicitations of a large company who had witnessed the proceedings with intense interest, that not all the triumph which attended this great work, and the solution of the difficult problem of carrying a rigid roadway across an arm of the sea at such a height as to allow the largest vessels to pass with all their sails set beneath it, could repay him for the anxieties he had gone through, the friendships he had compromised, and the unworthy motives which had been attributed to him; and that, were another work of the same magnitude offered to him with like consequences, he would not for worlds undertake it!

The Britannia Bridge was indeed the result of a vast combination of skill and industry. But for the perfection of our tools, and the ability of our mechanics to use them to the greatest advantage—but for the matured powers of the steam-engine—but for the improvements in the iron manufacture, which enabled blooms to be puddled of sizes before deemed impracticable, and plates and bars of immense size to be rolled and forged—but for these, the Britannia Bridge would have been designed in vain. Thus it was not the product of the genius of the railway engineer alone, but of the collective mechanical genius of the English nation.