TEASSACTIONS OF SECTION G. 865 



3. The Severn Tunnel. By T. A. Walker. 



After referriiifj to the incon-venience caused to traffic between Bristol aud tbe 

 towns of South Wales before the introduction of railways by the broud tidal 

 -estuary of the Severn and the detour which it necessitated in the Great AN esterii 

 Railway, the author mentions that a bridge was designed by Sir J. Fowler to 

 cross the river at Chepstow; but this project was subsequently abandoned, and in 

 1862 the company established a steamboat ferry at New Passage which was met 

 by trains at either side. Tbe tides, at times attaining a height of 45 ft., rendered 

 this arrangement very inconvenient, and in 1871 Mr. C. Richardson deposited 

 plans for the tunnel which has since been constructed. 



It is situated about three-quarters of a mile south of the line followed by the 

 steamboats, where the river is 2^ miles wide at high water, and the deep water 

 ■channel is cut through hard Pennant rock of tbe Coal Measures. The Act was 

 obtained in the Session of 1872, and the Great Western Railway Company com- 

 menced the works in February 1873. The new line, as designed and approved 

 T)y Parliament, consisted of a railway descending from the South Wales Railway 

 for about four miles on a gradient of 1 in 100 to the deepest part of the river, 

 inown as ' The Shoots,' and ascending from that point by the same gradient of 

 1 in 100 to join the Bristol and South Wales Railway near PUniug station, 

 the total length of the railway being about eight miles, and tbe length of the 

 tunnel four and a half miles. The thickness of rock above tbe crown of tiie arch 

 was in one place 15 ft., in another 30 ft., but generally from 80 to 100 ft. 

 The company made numerous preliminary experiments with a view to ascer- 

 tain the nature of the work to be undertaken, during which considerable 

 difficulties were experienced, owing to the large quantity of water met with. 

 These were continued till October 1879, when the heading on formation level 

 then being driven westward from the Sudbrook shaft tapped a great spring 

 of fresh water which proved to be in vastly greater volume than the pumps 

 could master, and in twenty-four hours the whole of the works in connection 

 with that shaft were drowned. The pumps at the other shafts also proved 

 unequal to the quantity which percolated from the adjoining heading, and the 

 works were brought to an entire standstill at the end of October 1879. 



The heading under the river had been advanced so far that only 130 yards 

 intervened between that being driven from Sudbrook eastwards and that driven 

 from the Gloucestershire side westwards. At this stage Sir John Hawkshaw, in 

 conjimctiou with Mr. Charles Richardson, took entire charge of the work, and the 

 contract was let to the author in December 1879. 



After narrating the various steps taken to remove the large quantitj^ of water 

 in the works and describing the difficulties met with, the paper states that by 

 November 1880 the depth of water was reduced to 30 ft. on the bottom heading. As 

 the progress was then particularly slow, and it was known that there existed at about 

 1,000 ft. under the river from the shaft an iron door, by which the water flowing 

 from under the river could be stopped from coming to the shaft, the author sent 

 one of the divers, named Lambert, with two assistant divers to help him, to try to 

 shut this door. As the length of hose he would have to drag with him to supply 

 Air to his helmet was 1,200 It., it was impossible for him to attempt this without 

 assistance. One diver was stationed in the bottom of tbe shaft to pull down tbe 

 hose and feed it forward into the heading. Lambert, with anotlier diver, then 

 proceeded about 500 ft. up the heading, and then Lambert alone, the other man 

 remaining at the end of 600 ft. to drag forward and feed to Lambert the floating 

 air hose as he advanced. By this means Lambert was enabled to reach within 

 :about 100 ft. of the door, but the friction of the hose on the roof of the heading 

 then became too great for his powers, and though he sat down and pluckily began 

 to draw the hose forward, and so proceed a few feet at a time, he was at last 

 compelled to give it up in despair and to return to the shaft defeated. 



Wearing the Fleuss diving dress, however, Lambert again proceeded on 

 November 8 to shut the door. He reached the door in safety, pulled up one of 

 the rails of the tramway which passed through it, but then, no doubt overcome by 



1887. 3 c 



