COURT OF INQUIRY
THE COURT CONVENES
A Court of Inquiry had been set up by Lord Sandon, the President of the Board of Trade, with commendable speed. Its instructions were that it was to hold a formal investigation into the causes of and the circumstances attending the accident to the Tay Bridge, Dundee, on Sunday 28 December, 1879, and it is worth pointing out that these instructions made no mention of allocating blame. The Court consisted of three men, Henry Rothery, the chairman and official Commissioner for Wrecks, Colonel William Yolland, the Chief Inspector for Railways, and William Henry Barlow, a professional engineer and also the current President of the Institution of Civil Engineers. Henry Law was appointed as engineering adviser to the Board of Trade, and Dr William Pole, the current Secretary to the Institution, as technical adviser to Bouch.
The Commissioners wasted little time in coming to Dundee, and the first sitting of the Court took place on the morning of Saturday, 3 January, 1880, in the city courthouse. The three principal interested parties – the Board of Trade, the North British Railway Company, and Bouch himself – had each engaged legal counsel, with Mr Trayner representing the Board, Mr J.B. Balfour the Company, and Mr George Bidder, Sir Thomas. The chairman began the proceedings by explaining the purpose of the preliminary hearing – to establish the ‘mere surrounding facts which may be locally ascertained’. More specifically he wanted to find out just what had happened on the night of the disaster, and also to establish the condition of the girders and the train, now lying on the bed of the river. He then adjourned the hearing until 2.00 p.m. to allow the Court to visit the scene of the disaster.115
The proceedings were resumed on the afternoon of Saturday, and continued on the Monday and Tuesday of the following week. The first group of witnesses to be heard were those employees of the railway who had been involved in the events of the 28th and had lived to tell the tale. These were the men whose accounts of the loss of the train have been told and retold on countless occasions since – Thomas Barclay, the signalman, and his friend John Watt; Henry Somerville, the signalman from the north box; stationmaster Smith from Taybridge Station; the stationmaster, ticket collector and porter from St Fort. But the picture that emerged from their accounts, clear enough in some particulars, left many questions unanswered. Not one of them had actually seen the train fall, and at best they could only speak of sudden flashes from the bridge, disappearing riding lights, and dark shapes in the murk. What they could agree on was at the time of its disappearance the train had not long entered the high girders, and their evidence on this point had already indicated to the diving parties where to begin their search.
Having questioned the employees of the railway company, the Court also heard from some members of the public who had been eyewitnesses of the tragedy – Alexander Maxwell, and the Clark brothers, George and William. Next came testimony as to the weather at the time of the fall – the scientific observations of Admiral Dougall and Captain Scott of the Mars, and the account of William McKelvie, superintendent of cemeteries in Dundee. According to McKelvie, the wind that had destroyed the bridge had also blown down eight or nine monuments in Balgay cemetery, and fifteen in the Eastern. No previous gale in his experience had done as much damage.
The last group of witnesses, the divers themselves, could add only a certain amount of information to this account, and that incomplete and confused. The problem, as we have seen, was a combination of appalling working conditions and poor overall direction of diving operations, but some facts could nevertheless be ascertained with some certainty, of which the most important was the position and disposition of the engine and its carriages. With this preliminary phase of the Inquiry completed, the Court was adjourned until some future date to be determined.116
THE PRECOGNITIONS
As it turned out the Inquiry was not to be resumed until February, and solicitors and agents for both the Board and the Company used the intervening period to track down witnesses and secure their testimony in the form of ‘precognitions’. Not unnaturally each side tended to select for the hearings only those witnesses whose evidence would do no damage to their cause. Thus the evidence of David Young, Albert Grothe’s boatman, described by Thornton as ‘a conceited vainglorious man’, would have been extremely damaging, if allowed to come out at the Inquiry. In the course of conversation in the solicitor’s office, he made such remarks as ‘The management of affairs at building the Bridge was extremely loose, and strict attention was not given to the construction and testing of the work…the iron was bad…ill made and deficient in quality . . . The concrete was not properly hardened . . . Mr Bouch’s examination of the work was very cursory.’ The evidence already referred to of James Edward, a painter with a grudge against the North British Company for refusing him the contract to repaint the bridge, would, if it had come to court, have alleged that there had been bad workmanship in the fixing of rivets and bolts in the ironwork of the girders and columns.117
The precognition of W.B. Thomson, proprietor of the famous Caledon shipyard on the Tay, likewise remained unproduced in court, but this time surely out of inadvertence rather than design. Thomson had been to church in Broughty Ferry on the Sunday of the fall, and had emerged into the storm a few minutes after seven o’clock. He had walked down to the beach, but the force of the wind had prevented him from getting right down to the sea front, and he had taken shelter at the corner of James Place. ‘While there,’ he told Thornton,
I distinctly saw two luminous columns of mist or spray travelling across the river in the direction of the wind. Another one formed in front of me just in an instant. It appeared to rise from the centre of the river. I never saw anything like this before, and looked round to see if anyone was near me, but seeing nobody thought it was better to take shelter. I went inside the railings in front of James Place, and held on by one of them thinking that the column, which was advancing towards me, was to carry everything before it. It passed over me. It was spray from the river, not solid water. It struck the house behind me with a hissing noise. The height of each of these columns was I should think 250 to 300 feet . . . My theory is that the north end of the bridge gave way first, the failure being caused by one such column rising or passing under it. Such a thing would tend to raise the girders from their piers, thereby overcoming part of the resistance offered to the lateral pressure of the wind. My theory put briefly is that there was a heavy upwards pressure as well as a lateral pressure in the wind that night. I never saw anything like it.118
Thomson’s theory, well founded or not, was at least in line with the Company’s argument that the weather was the real culprit, and it is surprising that Thornton did not see fit to call him on his clients’ behalf. But Thornton was perhaps preoccupied with trying to find witnesses who would help him rebut the evidence of another equally prominent witness - former Provost William Robertson, who was anxious to make public his conviction that on many occasions when he had travelled over the bridge, the driver had greatly exceeded the recommended 25 mph speed limit, and that the drivers regularly tried to race the ferry across the Tay in the mornings. He had often, he claimed, ‘heard the passengers twitting the driver that the Boat would race him this morning . . . I believe there was a wager made that the Boat would land its passengers first four mornings in one week. That week I thought the speed was very fast.’ By way of contradiction, Thornton had also interviewed one Frank Whitehurst, an upholsterer, who asserted that he had often travelled with Robertson, and had never known him complain of the speed. Whitehurst, however, refused to give evidence, and the North British, unlike the Board of Trade, had no power to compel him to do so. After recording Robertson’s precognition therefore, Thornton wrote to Adam Johnstone, chief solicitor for the North British, in Edinburgh to warn him of the danger, and advised him to have ‘two good and experienced engine drivers present who were in the practice of driving over the bridge, and would be able to say that they never exceeded speed, and never observed anything calling for remark or observation, and never felt any tremor or oscillation.’119
THE INQUIRY RESUMES
When the Inquiry resumed on 26 February, Robertson duly produced his story, claiming that he had once timed the train at nearly 43 mph, after which experience he had abandoned his season ticket and gone back to using the ferry. His complaints of excessive speed were supported by John Leng, proprietor of the Advertiser, and by other prominent citizens of Dundee. Against them was called one Henry Quosbarth, the German Consul, who asserted that he also had travelled regularly across the bridge, but had never done so at 40 mph, and had never experienced the slightest discomfort or anxiety. Stationmaster Smith was called, and was able to say that he had looked into Mr Robertson’s complaints, but had been unable to find any evidence to back them up. Not two but seven engine drivers were called, all of whom were adamant that they never exceeded the 25 mph speed limit, and that the crossing never took less than five and a half or six minutes. Allegations that the train on occasion used to race the ferry across the estuary were vigorously denied.120
And so the debate on the question of excessive speeds remained inconclusive. Much more damaging to the bridge-makers, however, was the evidence soon to emerge about the Wormit Foundry, and the tale of mismanagement, poor workmanship, and lax supervision which that evidence would reveal. The chief witness for this stage of the hearing was the foundry foreman, Fergus Ferguson, a self-regarding and complacent young man, who made the mistake of saying to Rothery, of the work of the foundry, ‘if I tried to explain it to you without you being a practical man you could never understand it’. Almost everything Ferguson said to the Court confirmed his lack of professionalism and good sense. He had taken it upon himself to decide on the thickness of the cast iron columns, regardless of his instructions. He contradicted himself repeatedly over the question of ‘burning on’ new lugs on columns where the original casting had been defective, and whether the process produced as strong a result as a properly cast column. His original estimate that he had had to break up some thirty or forty columns for defects in the casting became, under questioning from Trayner, something around two hundred. It soon became clear that for all his protestations he had failed to monitor the use of ‘beaumont egg’ to fill in blowholes in sub-standard castings. Of the casting iron itself, ‘he wouldn’t like to say it was the best, but as a general rule for building work it was not what you’d call terribly bad iron.’121
That Ferguson had got away with such inadequate workmanship for so long was due in turn to poor management by the contractors. Originally the foundry had been managed by its designer, Frank Beattie, a reasonably well-qualified and experienced engineer who had, or so he claimed, tried to persuade his employers to use better quality metal for the castings, but without success. Beattie was succeeded by Gerard Camphuis, a Dutchman formerly in the employ of de Bergue’s, who had been brought in because of his supposed expertise in driving piles for the bridge foundations, and had never before managed a foundry. Trayner ran rings round him, and by persistent questioning soon discredited his claim that despite his lack of experience he could ‘judge very well of foundry work’. The overall impression gained by this stage of the inquiry was of a foundry managed by incompetent and complacent staff, producing dangerously defective ironwork which had in fact failed to meet the test imposed upon it.122
After this interrogation of witnesses as to the affairs of the foundry, the Court turned to the question of maintenance. Here the key witness was the unhappy Henry Noble, formerly Bouch’s assistant in charge of the brickwork of the bridge, but since its completion the inspector of the Tay Bridge, in sole charge of all of the structure apart from the rails themselves.
Noble’s lack of qualifications for this responsible position were soon all too apparent. All he knew about was brickwork. He had begun his career as an apprentice bricklayer, and having served his time was employed by the Board of Works for nine years before being promoted to an inspector by the Metropolitan Board. As he freely admitted, he had no skills as an engineer, and no experience of ironwork. Yet here he now was, the inspector of a bridge of which five-sixths of the columns and all of the superstructure were made of iron. To carry out his duties, Noble had been given no instructions, a staff of seven (later reduced to three) and a small steamer, the Tay Bridge. Trayner had a field day. Having established that Noble had no experience of ironwork, and had been taken on by Bouch in 1871 as an inspector of brickwork only, he turned to Noble’s responsibilities with regard to the bridge:
– Then when you were taken on by the Company, I understand that your duties were to see whether or not there was any scouring at the bottom of the piers?
– Yes.
– Those were your special duties?
– Those were my special duties.
– They were in fact your only duties.
– They were the only duties I had really to perform.
– You said that you generally made your inspections in September and March.
– My soundings.
– What did you do at other times?
– I would go over the columns of the bridge.
– You were not appointed to do that.
– No, I know that.
On the question of what instructions Noble had received from the Company, Trayner asked:
– You never received instructions from them to report any default that you should discover in the structure of the bridge?
– No, I never had any such instructions.
– Had you general instructions to repair anything you might find defective without going to a superior in the company’s service?
– I never had any instructions at all . . .
‘So far as you know,’ Trayner persisted, ‘there was no one there charged at all with the duty of looking after the ironwork?’
– Not underneath the platform, but above there was.
– No one was there to look after the ironwork of the bridge as far as it stood between the top of the pier and the bottom of the platform?
– Except myself.
– You had no instructions.
– I had no instructions.
– Did any engineer make periodic visits to the bridge on behalf of the company? Was there a stated time, once a fortnight or once a week or once a month when any engineer came to look at the bridge and give it an overhaul?
– No.
– Did no one inspect the bridge from the time you went there, which was in May 1878, till its fall in December, 1879?
– No one but me.
– No one was there to judge the effect of the loosening of these bars or the proper measure to be taken to remedy these defects but yourself?
– Nobody but myself.
– Did you tell Sir Thomas Bouch at any time that you had heard this chattering of the bars, and what you had done?
– No, I never told him.
What he lacked in know-how, Noble made up in dedication. He examined the iron columns and discovered in several of them great long cracks which he did report to Bouch, and Bouch gave orders for them to be strapped round with iron. Likewise he found cracks in the masonry of a number of piers, and these too were repaired with iron strapping. He examined the foundations below water level and discovered that the scour of the river had gouged out great depressions – he had them filled with rubble. He inspected the tie-bars bracing the columns and found many of them loose, so he bought seven shillings worth of iron with his own money and used it to pack the loose ties, almost certainly fixing them permanently out of position.123
The next important witness was Albert Grothe, the man who had been largely responsible for the construction of the bridge, and who had been at pains, on so many occasions in the past, to quieten fears in the public mind about its strength and stability. To give him his due Grothe was willing to admit that there might have been some examples of poor workmanship, and that ‘in a large work like this, where there were 600 or 700 men employed, and with all materials floating in barges, it was impossible to keep so strict an eye on everything personally, as it would be in the same sort of work on shore.’ On the other hand he was confident that no cast-iron work was used in the bridge which had not passed at least a visual inspection, and he had given positive instructions on the point to Camphuis. Neither he nor Camphuis, he had to concede, were experienced foundry men, but had left the technical foundry work to Ferguson.
But he could not so easily disclaim responsibility for his earlier assurances that the bridge was more than capable of withstanding the severest storm ever known on the Tay, nor did he try. When asked for his opinion about the cause of the fall, he responded that in his view it had been brought about by the sheer force of the wind, and he freely acknowledged that his earlier view on wind pressures had been mistaken. ‘I see in my lecture,’ he confessed, ‘that I stated that the greatest wind that could ever be expected in this country was such a one as that in which the Royal Charter [sic] went down, when the pressure was 21 lbs per square foot, and upon that calculation I pointed out that the stability of the bridge was undoubted.’124
But had the bridge been designed to withstand even this much pressure from the wind, and what steps had its designer taken to ascertain the likely wind pressure in the Tay estuary? The court now turned to question Sir George Airy, the Astronomer Royal, who had been consulted on the subject of wind pressure in 1873, when Bouch was drawing up his plans for the projected bridge over the Forth. The full text of Airey’s opinion was read out in court. ‘We know,’ Airy had written, ‘that upon very limited surfaces, and for very limited times, the pressure of the wind does amount to sometimes 40 lbs per square foot, or in Scotland to probably more. However, I think we can say that the greatest wind pressure to which a plane surface like that of the bridge will be subjected to on its whole extent will be 10 lbs per square foot.’
In Airy’s view, occasional or localised gusts, or ‘irregular swirlings of the air’, which might exert a pressure of 40 or 50 lbs per square foot on limited portions of the bridge, were unlikely to have any effect on the structure as a whole. In his opinion 50 lbs was probably the greatest pressure exerted by any wind in Britain in recent years, though he had no idea what the wind pressure might have been on the night the bridge fell, as there were no instruments for measuring it in Dundee at the time. Not altogether helpfully, he observed that at its height the storm had registered not more than 10lbs per square foot at his residence at Greenwich. Since the bridge had fallen, he had written a paper on winds that had apparently blown down bridges, and advised for the future that ‘all calculations for the strength of a proposed structure should be based on the assumption of 120 lbs per square foot.’ If it was in fact true that 50 lbs was the highest pressure likely to be reached in practice, a figure of 120 lbs seemed like overkill.125
Airy was followed by a rather more credible authority on meteorology – a professor from Cambridge called Stokes, who lectured the court on wind speed of up to 90 miles per hour, and pressures in excess of 50 lbs per square foot. Nor should they think of gusts of that speed being of only momentary duration – ‘sometimes they will go on for two or three minutes, blowing very heavily indeed.’ Next came Mr Henry Scott, Secretary to the Meteorological Council, who supported Mr Stokes in every particular. Certainly, he confirmed, winds in the Tay valley could reach the speeds and pressures Stokes had mentioned, and they could exert their force along a wide front, perhaps as much as 250 feet. The picture of a bridge which would be unaffected by sudden gusts of wind was beginning to look less and less plausible.126
All this served as an essential backcloth to the main event of the Inquiry – the examination of the bridge’s designer, Sir Thomas Bouch. Bouch up to this point had remained apparently unaffected by the Inquiry, and had busied himself since the disaster with planning the bridge over the Forth, and even the repair of the Tay Bridge. But he can hardly have been by this stage unaware that his professional reputation was now very much at stake, not just in terms of his competence as a designer, but also in terms of the lack of supervision he appeared to have exercised over both the construction and the maintenance of the bridge. His ordeal lasted for a day and a half – the whole of Friday 30th April, and the morning of the following Monday. He answered more than eight hundred questions put to him by counsel and the three members of the Court, and he staunchly defended not only his own reputation but also those of his colleagues and employees, and made not the slightest attempt to pass any blame on to them. Henry Noble, he assured the Court, was ‘one of the best examiners of concrete and Portland cement I have come across in my experience, and one of the most careful.’ He was full of praise for Allan D. Stewart, his technical assistant, who had done most of the calculations for the bridge design, and who, as Bouch freely acknowledged, had better qualifications as a mathematician than his master. Nevertheless, Bouch assured the Court, the calculations of girder load carried out by Stewart had all been done on Bouch’s instructions.
Nor would he accept any criticism of the type of bridge he had chosen for the Tay – a design which he had used successfully on previous occasions, as in the Deepdale and Belah Viaducts. As for the cracks which had been discovered in the cast-iron columns, they had not caused him any great concern, and he had been informed that other notable bridge builders, including Brunel, had had similar problems but without any serious consequences. He had his own explanation for the disaster: ‘that it was caused by the capsizing of one of the last or the two last carriages – that is to say the second-class carriage and the van; that they canted over against the girder.’ Asked if that would have been enough to have destroyed the bridge, he responded, ‘I have no doubt of it. Practically the first blow would be the momentum of the whole train until the couplings broke. If you take the body of the train going at that rate, it would destroy anything.’ Yet he had to admit that in designing the bridge he had made no special allowance for wind pressure, and that admission alone was enough to ensure that he would leave the court with his professional reputation damaged beyond repair.127
THE VERDICT
The Report of the Court of Inquiry was presented to both Houses of Parliament in June, 1880. Unusually it took the form of two separate documents. The first of these, signed only by Yolland and Barlow, set out the facts of the case as revealed by the evidence before the Court, and made no attempt to ascribe blame or responsibility to anyone. The second report was written by Rothery, without the acquiescence of his two colleagues, but in which the pronoun ‘we’ was used throughout, giving the impression that it represented the views of all three. This document was damning, and if it was critical of many of the protagonists in the affair, it damned Sir Thomas Bouch in particular.
In their report, Barlow and Yolland concentrated on the failure of the supports of the bridge – in particular the cast-iron columns and their wrought-iron cross ties – and considered their deficiencies in terms of design, manufacture and construction. The key design issue was of course wind pressure, and the extent to which the designers had taken wind pressure into account. The report rehearsed in detail the evidence on wind pressure provided by the experts, and by Bouch and Stewart. It noted also that in the great majority of railway structures no special provision for wind pressure was required, ‘since the weight and lateral strength imparted to such structures in providing for the strains due to dead weight and load is more than sufficient to meet any lateral wind pressures which can arise’. Bouch, they noted, ‘having provided amply for dead weight and moving loads in the Tay Bridge . . . did not consider it necessary to make special provision against wind pressure.’
In the information which they, through Bouch, provided to the Court, Dr Pole and Allan D. Stewart had claimed that in designing the bridge, a maximum pressure of 20 lbs of wind pressure was assumed, plus the usual margin of safety.128 Taking this figure, and using it to calculate the stress on the cross ties, Barlow and Yolland reckoned that the ultimate strength of the ties should have been 45.88 tons. In theory, given the tensile strength of the iron used, and the cross-section of the ties, they should have been capable of bearing a load of 32.5 tons. But tests carried out for the Inquiry by Mr Kirkaldy showed that none of the ties tested came near to either of these figures. The mean ultimate strength of six ties tested without being attached to cast-iron lugs was only 25.6 tons, and of those attached to lugs, 24.1 tons. Moreover, ‘Mr Kirkaldy’s experiments show that the stretching or elongation of the ties, when tested with their fastenings, was greatly in excess of that due to elastic action of that material; a result attributable to the small bearing surfaces of the pins, gibs and cotters, and to the conical holes in the lugs.’
Similarly, with regard to the cast-iron lugs themselves, the tensile strength of the metal used for the lugs averaged 9.1 tons, yet in tests designed to simulate the stresses in situ, even sound lugs failed at less than 3 tons. ‘We believe,’ the report went on, ‘this great apparent reduction of strength in the cast iron is attributable to the nature of the fastenings, which caused the stress to be brought on the edges or outer sides of the lugs instead of acting fairly upon them.’
On the general question of wind pressure, then, and the ability of the bridge to withstand the force of an extreme gale, Barlow and Yolland concluded that if the cross-bracing had been made strong enough, then the stability of the bridge against overturning should have been sufficient to resist a wind force of 40 lbs pressure. Yet as they observed, the storm which occurred on the night of 28 December 1879 was recorded on board the Mars training ship, lying near Newport, as between 10 and 11 on the Beaufort scale, and was especially characterised by strong gusts at intervals. By this stage, some loosening of the ties had already taken place, as discovered by Henry Noble, and cracks had already appeared in some of the cast-iron columns.
In this state of the columns and ties, the storm of the 28th December 1879 occurred, which would necessarily produce great tension in the ties, varying as the heavy gusts bore upon different parts of the bridge; and when under these strains the train came on the viaduct bringing a large surface of wind pressure to bear, as well as increased weight on the piers, and accompanied by the jarring action due to its motion along the rails, the final catastrophe occurred.129
The second report, written by Rothery, came to broadly similar conclusions as to the defects of the structure and the causes of the fall. Where it differed was in its unequivocal attribution of blame. ‘It seemed to me,’ wrote Rothery, ‘that we ought not to shrink from the duty however painful it might be, of saying with whom the responsibility for this casualty rests . . . I do not understand my colleagues to differ from me in thinking that the chief blame for this casualty rests with Sir Thomas Bouch, but they consider it is not for us to say so.’ Rothery felt no such compunction.
The conclusion then to which we have come, is that this bridge was badly designed, badly constructed, and badly maintained, and that its downfall was due to inherent defects in the structure which must sooner or later have brought it down. Sir Thomas Bouch is, in our opinion, mainly to blame . . . For the faults in design . . . he was entirely responsible. For the faults in construction . . . he was principally responsible. For the faults in maintenance . . . he was principally if not entirely responsible.
The bulk of Rothery’s report was to substantiate these conclusions. The principal design fault, as he saw it, was in Bouch’s failure to make any allowance for wind pressure on the structure. There was no real excuse for this failure, and even if Bouch had had no accurate information about wind pressures in the Tay estuary, nevertheless he ought to have been aware that it was common practice in France for bridge designers to build in an allowance of 55 lbs, and in the United States an allowance of 50 lbs per square foot. It was unfortunate, furthermore, that Bouch had not taken more care to ascertain the true character of the river bed before embarking on the design of the columns and foundations, and if it was argued that he had been misled by the borers, ‘what right,’ Rothery demanded, ‘had Sir Thomas Bouch in a matter of such importance to trust solely to the word of the borers?’ No suggestion was offered as to how Bouch might have checked those findings.
As for the Wormit Foundry, the great lack was of proper supervision. Once again Rothery found Bouch very much to blame.
Sir Thomas Bouch seems to have left it to Hopkins, Gilkes & Co.; they left it to Mr Grothe, and he left it to Fergus Ferguson. With such supervision, or rather, we should say with the absence of all supervision, we can hardly wonder that the columns were not cast as perfectly as they should have been, and that fatal defects in the lugs and bolt-holes should not have been pointed out.
Yet if Bouch was to be awarded the lion’s share of blame, there was still plenty to go round. ‘We think also,’ wrote Rothery,
that Messrs Hopkins, Gilkes & Co. are not free from blame for having allowed such grave irregularities to go on at Wormit foundry . . . The Railway Company also are not free from blame for having allowed the trains to run through the High Girders at a speed greatly in excess of that which General Hutchinson had suggested as the extreme limit.
In addition to the question of blame, Rothery also addressed the central issue of cause, and here again he differed from the report of his two colleagues in that he gave considerable attention to Bouch’s claim that the bridge had been brought down, not by the force of the wind, but by the action of the train in coming into contact with the girders. It was not, however, a theory that appealed to Rothery. If the train had brought down the bridge, he argued, then the girders at the south end of the navigations spans, within which the train and carriages had been found, should have fallen first. While evidence on this point was admittedly inconclusive, what indications there were pointed to the northern spans having been the first to collapse. Marks or scrapes found on the eastern girders by Bouch’s assistant, Charles Meik, and which Bouch had claimed were proof of his theory that the last two carriages had canted over against the side of the bridge, were too superficial to account for the collapse.
So in the end Rothery’s explanation of the accident was little different from that of his fellow members of the Court. ‘What probably occurred,’ he wrote,
is this: the bridge had probably been strained, partly by the great speed at which the trains going northward were permitted to run through the High Girders. The result would be that owing to the defects, to which we have called attention, the wind ties would be loosened; so that when the gale of 28th December came on, a racking motion would be set up between the two triangular groups into which the six columns forming each pier were divided.
Add to this the motion of a great weight of a moving train, and the strain on girders, columns and piers was suddenly too much for the structure to bear. Train, girders, piers and all had collapsed into the river, and if the exact sequence of events and the precise causes of the collapse would never be known to the full, the result was essentially and tragically the same.130