Engineering Wonders of the World
Volume I

THE STORY OF THE SEVERN TUNNEL. 89 trance lift the water that finds its way into the cuttings and tunnel. Ever since the opening of the tunnel to general traffic the pumps have been ceaselessly at work, emptying some 24,000,000 gallons a day into the Severn—a quantity equal to about one-eighth of the water supply of London, and sufficient to form in one year a lake having a depth of 6 feet and an area of about 7 j square miles! Travellers through the darksome tunnel are probably quite unaware that they pass close to fourteen huge pumps, by which alone the safety of the great tube is preserved. The Severn Tunnel is a striking illustration of the extent to which a submarine is handicapped in the matter of drainage as compared with a big mountain tunnel, which can be, and is, so graded as to free itself of water by gravitation. The ventilation of the tunnel is performed by a huge Guibal fan, 40 feet in diameter, which extracts the foul air through a shaft at Sudbrook. To conclude with a few striking facts and figures. The construction of the tunnel occu- pied fourteen years. In the busiest seasons about 3,500 men were engaged. The lining of the tunnel con- Facts _ 1 • 1 ar,d sumed 77,000,000 bricks — Figures three - fifths of which were made on the spot — laid in about 37,000 tons of Portland cement. For the necessary blasting of rock 250 tons of explosives were used. The successful conclusion of this great under- taking was a triumph for Sir John Hawkshaw, Mr. Walker, and his doughty lieutenants. There are much longer tunnels in existence, but none of them has laid a heavier tax on the perseverance and resourcefulness of its engineers and their staff. A TRAIN EMERGING FROM THE SEVERN TUNNEL. {Photo, Great Western Railway Company.)