On the Fall of liivers. 



313 



The Fall of the Thames. 



I 



II. The Thames. — This noble river, although the most 

 important in Great Britain in a commercial point of view, is 

 only the fourth in point of magnitude. The entire length of 

 its course is 215'2 miles, which is 9 miles less than the 

 Shannon ; its descent is 376-3 feet. Unlike the Shannon, it 

 has a more equally distributed fall throughout its course ; 

 from its head to Lechlade, a distance of 22-0 miles, its fall is 

 6 feet ; and from thence to its mouth its average fall is only 

 1-2 feet per mile.* 



III. The Tweed. — We have already fully treated of this 

 river in the foregoing observations ; in point of area of its 

 basin it ranks ninth amongst British rivers. 



IV. The Clijde. — My results respecting the fall of this and 

 the preceding river are almost entirely based upon levellings ; 



* From Teddington to London Bridge it is IC ft. 9 in. at low, and I ft. Gin. 

 at liigh water. 



