256 PROCEEDINGS COTTESWOLD CLUB 1909 
because, in the absence of anything to divert it, the course 
is straight. On each side and parallel with it, are streams 
which pour in lower down, thus leaving the river itself 
with an unbroken bank. This is the explanation of the 
straight course. 
We now come to the Island of Alney at Gloucester. 
Here tributaries flow in on each side, and, of necessity, 
there is a channel on both sides. Below Gloucester, at 
The Rea, a tributary flows in on one side only and within 
recent years the river has continued to recede towards 
that side, on principles of which I gave an explanation in 
my paper of 1882. This is illustrated in fig. 9. 
Fic. 9.—The diagram (1) represents a river Mowing through alluvium. (2) The area effaced at 
ood time with river margin indicated: this, where the bank is weakened by a tribut- 
ary stream, is broken away. (3) A partial restoration of channel, the current being 
strong. (4) The same when the current is feeble. (5) A'promontory and river-curve 
developed from No, 4. 
I have often felt unable to understand the positive 
assertions made that the entrance of a tributary stream 
has the effect of driving a river towards the opposite bank 
and diverting its course in that direction. Even Mr Marr’ 
states that “as a consequence, main streams bend away 
from their tributaries where these join them.” But, asa 
question of fact, is this so? In my paper of 1882 I 
pointed out that tributaries generally come in on the 
convexities of river curves, and that the Severn and Avon 
1 “Scientific Study of Scenery,” p. 137. 
