94 THE SALMON RIVERS OF SCOTLAND 



peratures become approximated to the temperature of the main river, 

 or when their thermal conditions are already relatively high. Tem- 

 perature in this connection must be treated in close association with 

 volume of water. The volume of the Earn is greater than that of 

 many spring rivers, and its temperature does not appear to be 

 unduly low ; but it has the Tay to compete with at its mouth, and 

 for reasons to be described it has an insufficient stock of fish. 

 Between Dupplin and Earn mouth the river winds about like the 

 Eorth. At one point, near Forgandenny, a great loop has been cut 

 off, and in course of time other loops will no doubt be cut off. As 

 the crow flies, the distance to Dupplin is 9 miles, but by the course 

 of the river it is 14 miles. 



At Dupplin the first dyke occurs. This is a cruive dyke which 

 not many years ago was fished to the great detriment of the river in 

 general. The cruive box habitually had a rush of water through it 

 so heavy that it was seldom, even when the heck was off, that fish 

 could freely pass. I have seen fish lying so closely packed at the 

 sides of the white water rushing from the cruive box, that their 

 back-fins and tails were out of the water. I have lifted fish out by 

 the tail here and thrown them up over the obstruction. Needless 

 to say, at such times the river-watchers have always to be on the 

 spot. By an agreement amongst the various proprietors, this cruive 

 is now disused, and a pass has been constructed round the right- bank 

 end of the dyke. I am told that numbers of fish go through the 

 pass, and also that numbers of fish go over the dyke as they used to 

 do whenever the water-level is suitable for them to do so. It is the 

 presence of this dyke which is still responsible for the great collec- 

 tion of fish at the end of the season in the Dupplin Eeserved Water, 

 and for the great value of this fishing. Hence the very material 

 difficulty of regulating the fisheries of the Earn in the general 

 interest. 



And even if Dupplin Dyke were totally removed it would at once 

 become necessary to deal with the somewhat similar structures 

 further up. Strathallan, Millearn, Colquhalzie, and Brklgend or 

 Cook's Dykes have still to be negotiated, and there is not a pass 

 at any one of them. Another dyke formerly existed at Dornock, 

 below Crieff, but the two mills which derived water therefrom practi- 

 cally fell into disuse, and a merciful flood managing to make a 

 breach in the structure, Lord Ancaster, to whom it belonged, allowed 

 the natural gap to remain, and to be enlarged by subsequent floods. 

 Strathallan, like Dupplin, is a cruive dyke, the others supply water to 



