30 Observations on talcing doxin and 



is reduced to thirty-six inches per second, wlien the stones 

 remain at rest : proceeding among pebbles about an inch dia- 

 meter, it serves them the same, rising and spreading until its 

 velocity is reduced to twenty-tour inches per second, when they 

 remain at rest: proceeding through coarse gravel about the 

 size of a marble, it serves it the same, rising and spreading until 

 its velocity is reduced to twelve inches per second : and so it 

 proceeds with diminished velocity according to the size of the 

 grain, the velocity and the course always varying with the ob- 

 stacles met with. Gravel, the grain being about the size of 

 aniseed, will be at rest at a velocity of four inches per second. 

 Sand will remain at rest at a velocity of seven inches per second, 

 and precipitate at six inches per second. Clay will remain at 

 rest at a velocity of three inches per second *. By reference to 

 the map of the river Thames west of London Bridge, and bear- 

 ing the above-mentioned facts in mind, it will appear that the 

 banks of the river from Nine Elms, a little above Vauxhall 

 Bridge, to London Bridge may be considered artificially fenced, 

 and only requiring additional aid by raising and wharfing to 

 prevent ovei-flowing and sapping, through any increased height 

 and velocity of the current ; and, consequently, as the waters 

 ■will not be allowed to spread in a neighbourhood where land 

 is so valuable, the bed of the Thames in this part must be 

 deepened naturally if the current acquires increased velocity ; 

 and, therefore, the bridges, in this part, especially Vauxhall and 

 Westminster Bridges, which do not stand upon piles, must be 

 secured. If, proceeding from Fulham and impinging on the 

 s'lore of Wandsworth and Batterseaf, the water should find the 

 soil less resistive than on the opposite bank of the Grove, Chel- 

 sea, and Ranelagh, and the banks be not artificially strength- 

 ened, the water may take a short cut at some high flood in its 

 course to the sea, from Fulham to Nine Elms, and place Battersea 

 in Middlesex. The same principles will apply both to the effects 

 of the flood and ebb tides, from an increased velocity, at the 

 several bendings of the stream ; and, without expensive wharf- 

 ings and continual care after the dam is removed, the proprie- 

 tors of lands on the river shores, where there are elbows, may 

 expect sometunes to lose a rood, and sometimes an acre of 

 their lands, together with their sheep and cows. 



The present turbidness of the rivei-, and the frequent shifting 

 of some of the banks and shoals, show it to be now sometimes 



• See Principrs cf Hi/drnuUque, par M. le Chev. Dii Biiat; Experiences 

 .lur Ifs Cours tics Flenvcs, j)ar M. Gennctc ; and the article River, Ency.Brit. 



■\ The river here is comparatively rough and rapid. The boatmen have 

 a story, that a band of fiddlers at this place were in former times drowned, 

 and that the river has been dancinj: here ever since. Another band are de- 

 termined to make the land join in the jig. 



at 



