Page:Forth Bridge (1890).djvu/83

Rh of the Forth Bridge seven years ago he has resided on the spot. Mr. Phillips was specially interested in the sinking of the deep foundations of the main piers, and in the execution of which the contractors co-operated with, the eminent French contractors M. Coiseau. The difficulties of that part of the undertaking will be realised by what we have already said. Since the foundations were completed, Mr. Phillips has been actively engaged with Mr. Arrol in superintending the erection of the superstructure.

It would be, of course, too much to say that the foundations for the piers of the Forth Bridge could not have been so successfully carried out by English workmen and the firm of contractors who executed the remainder of the work; but it is certain that it was a wise decision to entrust this part of the undertaking to some one who had achieved a high reputation in the specially difficult work of sinking large foundations to a considerable depth, by means of compressed air. On the Continent works of this kind had been carried out on a much larger scale, and under greater difficulties than in this country, and no firm in the world has earned so high a reputation in this field as MM. Hersent and Couvreux. At the time—about 1880—when these contractors were carrying out the Antwerp Harbour works, at a cost of more than a million and a half sterling, their engineer-in-chief, M. L. Coiseau, had the responsibility of the foundations, a work similar in many respects to those of the Forth Bridge. Before this M. Coiseau had been engaged on heavy contracts upon the Suez Canal and the regulation of the Danube at Vienna. For a time he was a partner of Sir Thomas Tancred, and so became familiar with English methods of carrying out work, while at the same time he grew to be favourably and widely known by English engineers. It was during this period that he constructed a railway in Asia Minor. At the present time M. Coiseau is engaged in completing a large contract for the improvement in the port of Bilbao, on extensive railway undertakings in South America, and on other important works. There is no occasion for us to enlarge here on the manner in which he carried out the sub-contract for the sinking of the Forth Bridge caissons, as the details have been given on a previous page, but we may add that many important appliances used for pneumatic foundations have been designed by M. Coiseau. 

official inspection and testing by the Board of Trade Inspectors took place on Tuesday, the 18th February, and the two following days. The inspectors were Major-General Hutchinson, R. E., Major Marindin, K.E., and Major Darwin, R. E., and they were assisted by Mr. W. N. Bakewell and his assistants, of the Forth Bridge Surveying Department.

The conditions, as regards the structure, were the same as on the occasion of the preliminary trials excepting the following:—Ballast, consisting of coarse screened gravel to the extent of about 600 tons, had been distributed over the structure, being laid over the buckle-plates in the 6-ft. way, and between the troughs of the two lines; on the other hand a considerable amount of staging suspended from the cantilevers and central girders had been removed. The dead-weight in the end boxes of the two fixed cantilevers had also been increased to 1000 tons in each case. The trains used on this occasion consisted of:

The length of each train was :

The load was thus somewhat more concentrated than on the first occasion.

Along the footpaths on both sides of the internal viaduct stations had been prepared by driving in copper tacks upon which the levelling staffs were placed. There was a station at the centre of each tower, at each of the vertical columns, and at the ends of each bay in the cantilevers, also at each end and at the centre of the central connecting girders. All stations had been levelled several times over, and carefully checked and plotted. On the morning of the inspection, and previous to any train being allowed on the structure, the whole of the stations were gone over again, both by the Forth Bridge surveyors and, subsequently, by the officers of the Board of Trade Major-General Hutchinson taking one side and Major Marindin the other. The stations in the cantilever end piers and at the vertical columns were taken as fixed points, and all other levels were referred to these as benchmarks.

First Position of Trains.—The trains were now moved side by side over the south approach viaduct and along the Queensferry south cantilever until the front engines were close to the south vertical columns. Levels were now taken on both sides at every station, but only maxima are here recorded the intermediate deflections were throughout in proportion.

Second Position of Trains.—The trains were next moved forward on to the Queensferry north cantilever, the front engines being 6 bays into the south central girder the rear engine being about 40 ft. clear of the Queensferry north vertical columns. The results were as follows :

Third Position of Trains.—The trains were then moved on to the Inchgarvie south cantilever, the front engines being about 40 ft. short of Inchgarvie south; vertical columns, the rear engine 6 bays in south central girder. The results were :

Fourth Position of Trains.—The trains were next moved into the Inchgarvie north cantilever, the front engines 6 bays into the north central girder the rear engines 40 ft. outside Inchgarvie north vertical columns. The results were :

This concluded Tuesday's work.

Wednesday, 19th February, 1890.—The position of the locomotive engines were reversed this day—one in front, two in rear. The weights and lengths of trains remained the same.

Fifth Position of Trains.—The trains were first moved into the Fife south cantilever the front engine about 40 ft. short of the Fife south vertical columns—the rear engines 6 bays within north central girder. The results were: Upward deflection in Fife north cantilever—

Sixth Position of Trains.—The trains were then moved into the Fife north cantilever—the front engine