Page:Walker (1888) The Severn Tunnel.djvu/245

148 river Neddern—to construct a concrete invert in the bed of the brook for a length of nearly 4 miles.

This work was undertaken in August, and was completed by the 7th October; and three of the large engines and pumps being ready for work, on the 30th September it was determined at once to take in hand the work between Sudbrook and 5 miles 4 chains.

The sluices in the head-wall were gradually opened, and at the same time a hole was broken through the brickwork at the top of the head-wall.

In the first day’s work the head of water behind the head-wall was reduced 4 feet 6 inches, and after three days’ pumping all the water was out of the heading, and the foremen were able to go up and inspect the point where the spring had broken in. All the work was found in good condition, having been properly secured by timber just before the 10th October, 1883.

Another cross-heading was driven from the tunnel from behind the head-wall to connect with the side-heading; and the side-heading was pushed forward, and on the 19th December reached a large open joint in the strata, which had formed the channel for the subterranean water. A drawing is given showing a plan of this fissure, and the manner in which it was tapped by the side-heading.

By diverting the water of the spring into the side-heading the tunnel itself was left almost perfectly dry, except where, in taking out the invert, we