492 Sir Frederick Bramwell [Feb. 22, 



section being stopped, the movable part of that section should be 

 opened, and the ship should be allowed to come through. 



A Bill for a similar project was deposited in the present session 

 of Parliament by a private company. 



In the Report of the Parliamentary Committee to which I have 

 referred, is also to be found Telford's projiosition for a one-arch 

 cast-iron bridge, to replace London bridge. A diagram of it is on the 



wall. 



The Parliamentary Committee to whom this and other schemes 

 were referred took the advice of the scientific men of the day on the 

 subject ; among them was John Playfair, Professor of Mathematics at 

 Edinburgh College, who winds up his report of the '27th April, 

 1801, upon Telford's single-arch bridge, with words of modesty and 

 wisdom, which I think are well worthy of being repeated and of 

 being borne in mind : 



" I cannot, however, make an end of this report without observing 

 to the Committee that it is not from theoretical men that the most 

 valuable information in such a case as the present is to be expected. 

 When a mechanical combination becomes in a certain degree com- 

 plicated, it baffles the efforts of the geometer and refuses to submit 

 even to his most improved methods of investigation. This holds 

 particularly of bridges, where the principles of mechanics, aided by 

 all the resources of the higher geometry, have not yet gone farther 

 than to determine the equilibrium of a set of smooth wedges, acting on 

 one another by pressure only, and in such circumstances as, except 

 in a philosophical experiment, can hardly ever be realised. It is 

 therefore from men bred in the school of daily practice and ex- 

 perience, and who, to a knowledge of general principles, have added, 

 from the habits of their profession, a certain feeling of the justness or 

 insufficiency of any mechanical contrivance, that the soundest opinion 

 on a matter of this kind is to be obtained." 



Time will not admit, nor do I think you would be interested, 

 were I to call your attention in the most cursory manner (even by a 

 list of names) to all the various schemes that have, from the days of 

 the Thames Tunnel up to this date, been proposed for below-bridge 

 crossings, but I will at once mention some of the latest. These are — 

 the High Level Bridge, proposed by the Metropolitan Board of 

 Works, to span the river from Little Tower Hill (the road imme- 

 diately to the east of the Tower) to HorselydowTi Old Stairs ; the 

 Low Level Bridge at the same spot, with opening spans for the 

 passage of vessels, advocated by the Corporation ; and the Bill of 

 last year promoted by a private Company, for the making of a subway 

 parallel with the small subway I have already mentioned as 

 extending from Great Tower Hill, on the west side of the Tower. 



The question forces itself upon one — If, as appears self-evident, 

 some means of communication below bridge is needful, and has been 

 needful for the last fifty years, why has it not been made before this ? 

 The answer is^ the difficulties of suitable access, the difficulties of the 



