AND OTHER WATER WAVES 245 



It is between Hock Cliff and the Severn Bridge 

 that the bore usually commences, according to all 

 testimony. The river at low water below Hock 

 Cliff continues to flow in a single channel, the posi- 

 tion of which, however, is no longer fairly constant, 

 as at Newnham, but depends greatly upon the 

 quantity of land water. After a wet season it hugs 

 the left bank, cutting a deep trough in the loose 

 sands, and making as wide a bend as the permanent 

 bank permits. This is the condition which, accord- 

 ing to the testimony collected by the late Frank 

 Buckland I and also by myself, gives rise to a large 

 bore at Newnham, about four miles farther up. 



In dry seasons the channel, which contains all 

 the water during most of the time of ebb and 

 during the commencement of flood, lies much 

 farther from the eastern shore, taking a straighter 

 course. Presumably in this as in other cases which 

 I have noticed elsewhere, the shorter course is due 

 to the influence of the flood tide, which tends to 

 flow in a chord of the arc made by the ebb, or 

 river current. 2 After the dry season of the summer 

 of 1901, the ebb was flowing in such a channel, 

 far from the eastern shore and between perpen- 



1 '" Log-Book of a Fisherman and Zoologist," 1875. 



2 Geographical Journal, August, 1901 : " On Sand-waves in 

 Tidal Currents." 



