During the progress of the works, as the Summit Tunnel near Littleborough was approaching completion, the rumor was spread abroad in Manchester that the tunnel had fallen in and buried a number of the workmen. The last arch had been keyed in, and the work was all but finished, when a slight accident occurred which was thus exaggerated by the lying tongue of rumor. An invert had given way through the irregular pressure of the surrounding earth and rock at a part of the tunnel where a "fault" had occurred in the strata.
THE LITTLEBOROUGH TUNNEL. [The Walsden End.]
A party of the directors accompanied the engineer to inspect the scene of the accident. They entered the tunnel mouth preceded by upward of fifty navvies, each bearing a torch. After walking a distance of about half a mile, the inspecting party arrived at the scene of the "frightful accident," about which so much alarm had been spread abroad. All that was visible was a certain unevenness of the ground, which had been forced up by the invert under it giving way; thus the ballast had been loosened, the drain running along the centre of the road had been displaced, and small pools of water stood about. But the whole of the walls and the roof were as perfect as at any other part of the tunnel. The engineer explained the cause of the accident; the blue shale, he said, through which the excavation passed at that point, was considered so hard and firm as to render it unnecessary to build the invert very strong there. But shale is always a deceptive material. Subjected to the influence of the atmosphere, it gives but a treacherous support. In this case, falling away like quicklime, it had left the lip of the invert alone to support the pressure of the arch above, and hence its springing inward and upward. Stephenson then directed the attention of the visitors to the completeness of the arch overhead, where not the slightest fracture or yielding could be detected. Speaking of the work in the course of the same day, he said, "I will stake my character, my head, if that tunnel ever give way, so as to cause danger to any of the public passing through it. Taking it as a whole, I don't think there is another such a piece of work in the world. It is the greatest work that has yet been done of this kind, and there has been less repairing than is usual—though an engineer might well be beaten in his calculations, for he can not beforehand see into those little fractured parts of the earth he may meet with." As Stephenson had promised, the invert was put in, and the tunnel was made perfectly safe.
(Map of Midland Railway)
The construction of this subterranean road employed the labor of above a thousand men for nearly four years. Besides excavating the arch out of the solid rock, they used 23,000,000 of bricks and 8000 tons of Roman cement in the building of the tunnel. Thirteen stationary engines, and about 100 horses, were also employed in drawing the earth and stone out of the shafts. Its entire length is 2869 yards, or nearly a mile and three quarters, exceeding the famous Kilsby Tunnel by 471 yards.
The Midland Railway was a favorite line of Mr. Stephenson's for several reasons. It passed through a rich mining district, in which it opened up many valuable coal-fields, and it formed part of the great main line of communication between London and Edinburg. The line was originally projected by gentlemen interested in the London and Birmingham Railway. Their intention was to extend that line from Rugby to Leeds; but, finding themselves anticipated in part by the projection of the Midland Counties Railway from Rugby to Derby, they confined themselves to the district between Derby and Leeds, and in 1835 a company was formed to construct the North Midland line, with George Stephenson for its engineer. The act was obtained in 1836, and the first ground was broken in February, 1837.
Although the Midland Railway was only one of the many great works of the same kind executed at that time, it was almost enough of itself to be the achievement of a life. Compare it, for example, with Napoleon's military road over the Simplon, and it will at once be seen how greatly it excels that work, not only in the constructive skill displayed in it, but also in its cost and magnitude, and the amount of labor employed in its formation. The road of the Simplon is 45 miles in length; the North Midland Railway 72-1/2 miles. The former has 50 bridges and 5 tunnels, measuring together 1338 feet in length; the latter has 200 bridges and 7 tunnels, measuring together 11,400 feet, or about 2-1/4 miles. The former cost about £720,000 sterling, the latter above £3,000,000. Napoleon's grand military road was constructed in six years, at the public cost of the two great kingdoms of France and Italy, while Stephenson's railway was formed in about three years by a company of private merchants and capitalists out of their own funds and under their own superintendence.
It is scarcely necessary that we should give any account in detail of the North Midland works. The making of one tunnel so much resembles the making of another—the building of bridges and viaducts, no matter how extensive, so much resembles the building of others—the cutting out of "dirt," the blasting of rocks, and the wheeling of excavation into embankments, is so much matter of mere time and hard work, that it is quite unnecessary to detain the reader by any attempt at their description. Of course there were the usual difficulties to encounter and overcome, but the railway engineer regarded these as mere matters of course, and would probably have been disappointed if they had not presented themselves.