Engineering Wonders of the World
Volume I

THE STORY OF THE SEVERN TUNNEL. 81 of this a drainage heading was driven eastwards on a slightly rising gradient, so as to drain the tunnel at its lowest point under the Shoots. By the year 1877 about 1,600 yards of tunnel heading had been driven, and a second shaft, slightly to the north of the Old Shaft, half sunk. The directors then decided to let the contract for the tunnel, but into the Iron Shaft. A few hours later the workings had been drowned completely, the water standing 150 feet deep in the shafts, up to tide level. Its sweetness proved, how- ever, that it had no connection with the river. Dismayed by so untimely a result of seven years’ work, the directors asked Sir John Hawkshaw, their consulting engineer, to take THE SEVERN TUNNEL. the position of the door closed by Diver Lambert, on second thoughts determined to first “ prove the ground ” by a heading through the whole length of the tunnel. They accordingly com- pleted the second shaft, lined it with iron, joined it by a short passage to the Old Shaft, and installed pumps in it. The “ Sea Wall ” Shaft was also sunk on the Gloucestershire side, and two more—the “ Marsh ” and “ Hill ” Shafts—on the western bank. The position of these is shown in the longitudinal section of the tunnel given on page 80. Towards the end of 1879 the first of several disasters which punctuated the history of the undertaking occurred. On October 18 the miners working westwards on Inrush the Upgraje from Old Shaft of Water , , , . , . , struck water, which poured from r Great Spring. out 8u°h quantities from some subterranean reservoir that the men had to run for their lives. The water, on reaching the Old Shaft, fell with a roar some 40 feet to the level of the drainage tunnel, the filling of which gave the men time to make their escape through the cross tunnel (1,408) full charge of operations. This he consented to do on condition that the contract for the completion of the tunnel should be given, to Mr. T. A. Walker, who had won his spurs under him in connection with the Metropolitan Railway and the East Londoi) Railway. This condition was granted, and the contract signed at the end of 1879. Mr. Walker at once proceeded to tackle the Great Spring, as the men named it, which had PLAN OF THE SHIELD FIXED AT THE BOTTOM OF THE OLD PIT TO EXCLUDE THE WATER FROM THE GREAT SPRING. 6