SALMON. 43 



is occasioned by these creatures, which bore through the 

 gravel. 



Strongly, however, as all these causes operate, there 

 is one more destructive than all of them put together ; 

 namely, the effect of the furious spates which are 

 continually taking place in the Tweed, and which put 

 the channel in motion, and often sweep away the 

 spawning beds altogether. 



Before the hills were so well drained as at present, 

 this was not so much the case ; as the mosses gave out 

 the water gradually, and the river continued full for a 

 long time, to the great solace of the rod fisher. But 

 now every hill is scored with little rills which fall into 

 the burns, which suddenly become rapid torrents and 

 swell the main river, which dashes down to the ocean 

 with tremendous violence. Amidst the great din, you 

 may hear the rattling of the channel stones, as they are 

 borne downwards. Banks are torn away ; new deeps 

 are hollowed out, and old ones filled up ; so that great 

 changes continually take place in the bed of the river 

 either for the better or the worse. 



When we contemplate these things, we must at once 

 acknowledge the vast importance of Mr. Shaw's experi- 

 ments; for if ponds were constructed up the Tweed 

 at the general expense, after the model of those made 

 by him, all these evils would be avoided. The fry 

 might be produced in any quantities by artificial im- 

 pregnation ; be preserved, and turned into the great river 

 at the proper period of migration. There might at 

 first be some difficulty in procuring food for them ; but 

 this would easily be got over. At a very small expense, 



