At

decide to whom the palm is due? any rate, the idea of riveting by machinery remained to a great degree unapplied in the work of engineering until Arrol's invention. He so applied the wellnigh irresistible force of hydraulic pressure (1000 lb. to the square inch), as to be easily transported in every direction by movable and flexible tubes. Thus was introduced the swiftness-about seven rivets in a minute-efficiency, and ease in actual practice which led to its universal application in shipbuilding and boilermaking as well as in bridge-work. As usual in such cases, he was not allowed to enjoy the fruits of his ingenuity without a struggle. A certain Mr Tweddle considered the new machine was infringing on a patented invention of his own, and brought an action against Arrol in the Scottish Courts. The leading advocates of the day were retained. For Tweddle were Mr Balfour, afterwards Lord Justice-General of Scotland, and Robertson, who became

a Lord of Appeal in Parliament; while Asher, Q.C., some time Solicitor - General for Scotland, and Mackintosh, afterwards Lord Kyllachy, were counsel for Arrol. In the end it was decided that Arrol's movable tubes justified his patent, and thenceforward he was allowed to enjoy the benefits of his invention with none to say him nay.

But now it is high time to pause from these sketches in outline of Arrol's work, and come with more detail to those two masterpieces by which his name will always be most widely known-viz., the great bridges of the Tay and the Forth.

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CHAPTER III.

THE TAY BRIDGE.

In the year 1882, when Sir William Arrol was already engaged in the early stages of the work he had taken in hand to carry out Sir Thomas Bouch's design for a suspension bridge across the Firth of Forth, he was brought to a standstill there and a new call was made on his energies for an enterprise almost as great. A terrible disaster suddenly befell Sir Thomas Bouch's new bridge over the Firth of Tay. This viaduct, perhaps the longest in existence, had been opened for traffic on the 31st of May 1878. Only a year and seven months afterwards, during the night of the 28th December 1879, in a great

gale of wind, the thirteen central spans of 245 feet each, together with a train passing over at the time, fell and disappeared in the river beneath. Only the broken columns were left to show at daybreak where yesterday had stood that part which bridged the mid-channel of the Tay. It was one of the greatest disasters that had ever occurred to an engineering structure. More than eighty lives were lost, and the whole country was in dismay at the fall of such a noted bridge. A long official inquiry followed, which showed that the vertical columns of the piers, though standing on perfect foundations and strong enough in themselves for any weight they were required to bear, were not well enough braced together to withstand the lateral pressure of the wind. This, it seems, had led to the downfall.

The importance of a bridge over the estuary of the Tay was second only to that to be built over the estuary of the Forth; or indeed it may be said they had one

ultimate object in common-that of direct railway communication between the towns and coalfields in the North of Scotland and nearly all the rest of Great Britain south of the Forth. The North British Railway Company promptly took steps to restore that link in the contemplated connection which had so soon and so suddenly been broken. A Bill was at once brought before Parliament for the erection of a new bridge, with great improvements on the old, but to stand on what it stood and include much of its remains. Doubts arose whether the old foundations would bear the new weight of what was required for complete security, and the Bill was rejected. The Railway Company, however, were not discouraged. They renewed the attempt, and in the next session their Bill was remitted to a Select Committee. This Committee reported that they had no doubt a bridge, if properly built, would resist the lateral pressure of any wind. They advised the reconstruction, and the Company left the problem