1921] Severn Crossings and Tidal Power 315 



WEEKLY EVENING MEETING, 

 Friday, March -4, 1921. 



J. H. Balfour Browne, K.C. D.L. J.P. LL.D., 

 Vice-President, in the Chair. 



W. A. Tait, M.Inst.C.E. M.R.I. 



Severn Crossings and Tidal Power. 



Several very pretty engineering: problems have arisen in regard to 

 the crossings of estuaries and rivers on the British coast. 



It is interesting to note that the Thames, Forth and Tyne were 

 in turn pioneers in less usual forms of crossing — thus : 



1. The Thames was first with subaqueous tunnelling, and after- 

 wards with a bascule bridge. 



2. The Forth was first with a train ferry, and afterwards with a 

 cantilever bridge. 



3. The Tyne was first with a double-decked bridge arranged to 

 carry both road and railway traffic. 



Brunei's Thames Tunnel, between Wapping and Rotherhithe, 

 was intended to enable road traffic to be taken directly across the 

 Thames without going a journey of several miles up to and down 

 from London Bridge through as busy thoroughfares as are to be 

 found anywhere. This tunnel was driven through mud without the 

 aid of compressed air, and was opened in 1843, after having occupied 

 nearly eighteen years in construction, including a stoppage of about 

 seven years owing to want of funds. 



The work was carried on under the direction of the first and 

 second of the illustrious trio of Brunels. The length of the tunnel 

 is about a quarter of a mile, and it was completed at an overhead 

 cost of about £1,300 per lineal yard, arid was probably one of the 

 most costly forms of construction ever carried out. The work was 

 frequently interrupted by the Thames breaking in. 



(A slide was thrown on the screen showing the measures taken 

 to stop an inrush of water. The slide also showed men going up to 

 the leading end of the tunnel in a boat.) 



The tunnel seems only to have been completed in the first 

 instance between the shafts on either side of the river, and to have 

 been then used for foot passengers ; some shops were opened inside. 



It was acquired in 1865 by the East London Railway Co. for 

 VOL.XXIIL (No. 115) *z 



