Page:Walker (1888) The Severn Tunnel.djvu/257

154 in, at a point nearly midway between Sudbrook and 5 miles 4 chains shaft.

The brickwork of the tunnel having been completed, the side-heading was arched over above the level of the water from the Great Spring, and over the arch filled up with rubble masonry from the point where the western end intersected the fissure. When the door was reached, one of the sluices was shut on July 13, and a 12-inch pipe being laid to carry the water from the other, the rest of the heading was filled up with rubble masonry, and the opening through the side-wall of the tunnel closed. The 12-inch cast-iron pipe was laid to bring water from the spring to the boilers, and a small shaft was sunk at the side of the tunnel, nearly over the end of the side-heading, and a pipe led down through the shaft to connect with the pipe in the heading.

In addition to the sluice at the head-wall, a sluice was fixed on this pipe at its eastern end. The sluice by the head-wall was opened before the heading was filled with masonry, and the sluice at the other end was kept at our command for supplying water as might be hereafter required. At the end of the cast-iron pipes a pressure-gauge was fixed to the pipes to indicate the pressure of the water, and so tell how much it had risen day by day. The following table shows the rate at which the water rose: