Page:Walker (1888) The Severn Tunnel.djvu/85

34 been completed on the 7th, and ten days had been occupied in removing the pumps from the old pit to the new.

A heading had been driven eastwards before the contract was let to me, for a distance of 1,020 feet from the Sea-Wall Shaft. Some time in the summer of 1879, the roof at the end of this heading broke through the marl into a bed of gravel. There had been a great run of gravel and water, and the heading was partly filled. A head-wall had been built across the heading, 240 feet from the shaft, with a door. The door had then been closed, and the water from the gravel shut out. Before the new shaft was commenced, this door was opened, and the heading east of it examined. It was found to be in a bad state, supported by very small timbers, and not at all safe. Some extra timber was put in, and the door, which had been fixed by the Company in this heading, was again closed.

Another cross-heading was driven to suit the new gradients after the pumps were fixed at Sea-Wall, and a commencement was made at lowering the heading westwards to the altered levels.

To secure the ground, a small piece of the tunnel was commenced in a peculiar way, which was afterwards largely adopted.

The lowering of the gradient to so great an extent as 15 feet made the existing headings useless for drainage purposes, and it was decided to put in the arch of the tunnel down to springing