The land-owners having been thus "conciliated," the promoters of the measure were at length permitted to proceed with the formation of their great highway. Robert Stephenson was, with his father's sanction, appointed engineer-in-chief of the line, at a salary of £1500 a year. He was now a married man, having become united to Miss Frances Sanderson in 1829, since which his home had been at Newcastle, near to the works there; but, on receiving his new appointment, he removed with his wife to London, to a house on Haverstock Hill, where he resided during the execution of the Birmingham Railway.
Steps were at once taken to proceed with the working survey, to prepare the working drawings, and arrange for the prosecution of the undertaking. Eighty miles of the line were shortly under construction; the works were let (within the estimates) to contractors, who were necessarily, for the most part, new to such work. The business of railway construction was not then well understood. There were no leviathans among contractors as now, able to undertake the formation of a line of railway hundreds of miles in length; they were, for the most part, men of small capital and slender experience. Their tools and machinery were imperfect; they did not understand the economy of time and piece labor; the workmen, as well as their masters, had still to learn their trade; and every movement of an engineer was attended with outlays, which were the inevitable result of a new system of things, but which each succeeding day's experience tended to diminish.
(Map of London and Birmingham Railway)
The difficulties encountered in the construction of this railway were thus very great, the most formidable of them originating in the character of the works themselves. Extensive tunnels had to be driven through unknown strata, and miles of underground excavation had to be carried out in order to form a level road from valley to valley under the intervening ridges. This kind of work was the newest of all to the contractors of that day. Robert Stephenson's experience in the collieries of the North rendered him well fitted to grapple with such difficulties; yet even he, with all his practical knowledge, could scarcely have foreseen the serious obstacles which he was called upon to encounter in executing the formidable cuttings, embankments, and tunnels of the London and Birmingham Railway. It would be an uninteresting, as it would be a fruitless task, to attempt to describe these works in detail; but a general outline of their extraordinary character and extent may not be out of place.
The length of railway to be constructed between London and Birmingham was 112-1/2 miles. The line crossed a series of low-lying districts, separated from each other by considerable ridges of hills, and it was the object of the engineer to cross the valleys at as high an elevation, and the hills at as low a one as possible. The high ground was therefore cut down, and the "stuff" led into embankments, in some places of great height and extent, so as to form a road upon as level a plane as was considered practicable for the working of the locomotive engine. In some places the high grounds were passed in open cuttings, while in others it was necessary to bore through them in tunnels with deep cuttings at either end.
The most formidable excavations on the line are those at Tring, Denbigh Hall, and Blisworth. The Tring cutting is an immense chasm across the great chalk ridge of Ivinghoe. It is two miles and a half long, and for a quarter of a mile is fifty-seven feet deep. A million and a half cubic yards of chalk and earth were taken out of this cutting by means of horse-runs, and deposited in spoil-banks, besides the immense quantity run into the embankment north of the cutting, forming a solid mound nearly six miles long and about thirty feet high. Passing over the Denbigh Hall cutting, and the Wolverton embankment of a mile and a half in length across the valley of the Ouse, we come to the excavation at Blisworth, a brief description of which will give the reader an idea of one of the most formidable kinds of railway work.
BLISWORTH CUTTING. [By Percival Skelton.]
The Blisworth Cutting is a mile and a half long, in some places sixty-five feet deep, passing through earth, stiff clay, and hard rock. Not less than a million cubic yards of these materials were dug, quarried, and blasted out of it. One third of the cutting was stone, and beneath the stone lay a thick bed of clay, under which were found beds of loose shale so full of water that almost constant pumping was necessary at many points to enable the works to proceed. For a year and a half the contractor went on fruitlessly contending with these difficulties, and at length he was compelled to abandon the adventure. The engineer then took the works in hand for the company, and they were vigorously proceeded with. Steam-engines were set to work to pump out the water; two locomotives were put on, one at either end of the cutting, to drag away the excavated rock and clay; and eight hundred men and boys were employed along the work, in digging, wheeling, and blasting, besides a large number of horses. Some idea of the extent of the blasting operations may be formed from the fact that twenty-five barrels of gunpowder were exploded weekly, the total quantity used in forming this one excavation being about three thousand barrels. Considerable difficulty was experienced in supporting the bed of rock cut through, which overlaid the clay and shale along either side of the cutting. It was found necessary to hold it up by strong retaining walls, to prevent the clay bed from bulging out, and these walls were farther supported by a strong invert—that is, an arch placed in an inverted position under the road—thus binding together the walls on both sides. Behind the retaining walls, a drift or horizontal drain was run to enable the water to escape, and occasional openings were left in the walls themselves for the same purpose. The work was at length brought to a successful completion, but the extraordinary difficulties encountered in executing the undertaking had the effect of greatly increasing the cost of this portion of the railway.