34 PRACTICAL FLY-FISHER. 



Grayling are never found in any quantity in rivers 

 running through exposed mountainous districts ; nor are 

 they found in rivers whose chemical constituents are of a 

 cold, saline nature ; thus the geological character of the 

 bed of the river influences them. They seldom get to a 

 great size in rocky or gravelly streams, but require a 

 combination of sand and loam. In most rivers, where 

 they attain a large size, the current is never very rapid, 

 but is generally found to be a combination of pool and 

 stream ; and the vegetation on the bank of the river 

 seems to exert a particular influence over them, as they 

 seldom thrive in any stream running through a barren 

 district ; this may be accounted for to a certain extent 

 by the want of insect life, to be found in such situations. 



It would therefore seem that a good Grayling 

 river should have four requisites ; 1st, a moderately 

 warm temperature of the external air and the water : 

 2nd, a particular chemical constitution of the water : 

 3rd, a mixture of pool and stream : and 4th, a culti- 

 vated country, through which it runs. In the Aire T 

 Wharfe, and the Rye, these are to be found ; but more 

 particularly in the Eye, which is the best Grayling 

 river I know. It is one continuation of pool and stream, 

 and in fact contains all the advantages I have just men- 

 tioned. I shall return to a description of those streams 

 in the course of this chapter. 



Not only do we find the Grayling occupy a differ- 

 ent portion of the stream, but his habits of feeding differ 

 from those of the Trout ; he is seldom taken in the 

 rough and rapid streams, but more generally in the still 

 water, or eddies by the side of them. Their favourite 

 places for feeding would seem to be either in the slow 



