Page:Walker (1888) The Severn Tunnel.djvu/72

Rh , the road to be a cross-sleepered road with steel rails weighing 86 lbs. to the lineal yard of rail.

The original amount of the contract was very considerably increased, firstly, by the whole of the tunnel having an invert; secondly, by the brickwork lining being made 3 feet thick, instead of 2 feet 3 inches, over a considerable part of the length of the tunnel; and, thirdly, from the lowering of the whole of the gradients, which will be mentioned later.

The clause in the contract which stated that the 660 yards under the ‘Shoots’ were to be completed before the rest of the work was proceeded with, was inserted because the Directors and the engineer still thought the chief danger in constructing the tunnel was from an irruption of the river-water; and no one supposed that there lay hidden under the land, within a quarter of a mile of the western shore, a greater difficulty and danger than any to be met with under the bed of the river. The very precautions which were taken for security under the river were the cause of magnifying the other difficulties, and there never was a clearer case of ‘De Scylla in Charybdim.’