Page:Walker (1888) The Severn Tunnel.djvu/255

152 The work remaining to be done being now confined to a very short length, it was necessary to reduce largely the number of men employed, but as many were retained as could be kept at work, and in order to hasten completion, four break-ups were started in the short length near the Great Spring, at distances of only 44 yards apart. The running lengths were also commenced from both faces, and thus ten faces were kept at work through this short length of tunnel.

On opening out the full-sized tunnel, the fissure through which the Great Spring had passed was found to follow a most erratic course. In one place it passed directly across the tunnel from side to side, nearly at right angles to the centre line of the work. At another place it passed from side to side in an oblique direction, running for some small distance directly under one of the side walls. At another point where the tunnel had been perfectly dry, while the mining was done, the lifting of almost the last stone out of the invert set free an immense body of water which no pumps underground could cope with. At another point the water boiled up from a hole 18 feet in depth under the invert with such force that stones, the size of a man’s fist, dropped into the water would descend about 10 feet, and then begin to flutter like a leaf in the wind, and be thrown out again by the water. Into this hole a cast-iron pipe was lowered, attached to a bend at the top to lead the water into the side-heading.