Jrom the Removal of London Bridge. 27- 



shown that the removal of London Bridge will admit a greater 

 body of water to flow up the river to the westward, and with a 

 greater velocity, which together will considerably increase the 

 momentum ; and it is equally certain that the same cause will 

 operate in the ebbing tide, and leave the bed of the river nearly 

 dry for several hours in tiie latter part of the ebb. This will 

 in part be remedied by the increased velocity and momentum 

 scouring away the mud, sand, and small gravel, so as to deepen 

 the bed ; but this cannot take place where the matter has 

 more consistence, and to obtain the same depth as at present 

 at low water would require excavation to a very great extent, 

 probably to incur an expense of 40,000/. 



But this lowering of the bed, if accomplished either by the 

 tide scour or artificial excavation, would seriously affect the 

 foundations of some of the other bridges. The piers of West- 

 minster Bridge stand upon gravel without having piles under 

 them, and several are now not more than 3 feet under the pre- 

 sent surface of the river bed, the matter of which I proved to 

 be sand and gravel. By the plate of the geometrical elevation 

 and plan of Blackfriars' Bridge, published from drawings by 

 Mr. Baldwin, the bottom of the platforms is not more than 

 about 5 feet below the present bed of the river: these piers have, 

 it is true, piles of about 10 feet in length under them, but if 

 the bed were lowered they would require to be protected. 

 Some of the piers of Waterloo Bridge have their platforms 

 laid only at about 6 feet 4 inches under the line of the present 

 low-water mark. Respecting the bridges between Westmin- 

 ster and Teddington, which stand partly on stone piers and 

 partly upon wooden piles, I have not hitherto been able to 

 obtiiin any accurate information; but it is clear that the lower- 

 ing of the bed of the river would in some measure affect them. 



With regard to wharfs and houses built on the banks of the 

 river, the lowering of the surface of low water, and extending 

 the time of that depression, would afford an opportunity of a 

 greater drainage fi-om the adjacent soil upon which buildings 

 are erected, and may have the effect of causing settlements : if 

 no excavation takes place in the shores adjacent to the wharfs, 

 the barges, &c. will be longer prevented from approaching to 

 or departing from them : if an excavation does take place, 

 there will be some risk of the walls being imdermined. These 

 observations apply to the whole river as far as Teddington. 



Besides these consequences from lowering the bed of the 

 river, others will unavoidably follow from the tide above Lon- 

 don Bridge rising higher than it does at present. Many of 

 the wharfs by the sides of the river are not more than from 

 1^ to 2 feet above Trinity Datum, and are not unlicquentlv 



D 2 overflowed, 



