50 



Professor Barlow on the Tides 



5. The difference of level between the high and low water, 

 at several places on the river, and other miscellaneous particu- 

 lars. 



1. Sectional areas of water-way at London Bridge, and at 

 Southward y Blackfriars, Waterloo, and Westminster Bridges, 

 at different periods and states of' the tide. 



The linear water-way at London Bridge between the Piers Ft. itu 



above the Starlings, - - - _ . 524 2 



Linear distance occupied by the Piers, - _ . 406 10 



Total distance between the abutments, - . _ 931 



' Linear water-way below the Starlings at low water, - 230 11 



Linear distance occupied by the Starlings, - - 7OO 1 



From this table it appears, that, at low water spring-tide, the 

 sectional area of the water-way at London Bridge is not more 

 than about two-fifths of that at Waterloo Bridge, which has the 

 least water-way at low water of the other four bridges ; this con- 

 traction acts as a dam, and causes the water to accumulate so 

 much above bridge, that the sectional area below bridge is very 

 little more than one-third of that above bridge. 



And at high water spring-tide, the water-way at London 

 Bridge is, at a medium, about half that at Southwark, which 



