Page:Walker (1888) The Severn Tunnel.djvu/244

Rh end of the tunnel was led into the tunnel itself, and pumped by the pumps fixed in the Sea-Wall pumping-shaft.

The two 70-inch engines and the two 60-inch engines were being erected in the houses provided for them, and the pumps were being fixed in the shafts.

In order to deal with the water from the Great Spring, Sir John Hawkshaw decided to drive a side-heading parallel to the centre-line of the tunnel, but about 40 feet to the north of it, from the Old Pit at Sudbrook to the point where it would intercept the spring itself.

The gradient of the tunnel rising 1 in 90, the heading was to be driven at a gradient of about 1 in 500; so that, when it reached the point where the Great Spring had broken in, it would be about 3 feet below the bottom of the invert of the tunnel.

The driving of this heading was commenced in July, both from the point at which it was to join the tunnel and at a point 50 yards to the west, by a cross-heading from the tunnel, in order to ensure the correctness of the lines. By the 20th September this side-heading had been driven about 18 yards past the point where the head-wall had been built across the tunnel.

Sir John Hawkshaw had further decided that, in order to reduce, if possible, the quantity of water to be dealt with—which, we knew, to a very considerable extent came from the loose bed of the little