178 SALMON! A. [seventh day. 



be fitted to bear changes, which would have destroyed 

 their progenitors. It is said by Block, that graylings 

 are found in the Caspian sea, and in the Baltic, — 

 masses of saline water ; though, as I have proved, the 

 grayling of England will not bear even a brackish 

 water without dying. And notwithstanding the 

 severity of the winter in high northern latitudes, 

 streams under the ice may retain a temperature not 

 much lower than some of the Alpine rivers. I have 

 seen grayling in Carniola, in a source at the hottest 

 season, not quite 50°; and as, in large bodies of 

 water, the deepest part, in frost, is generally the 

 warmest, about 40°, the degree at which water is 

 heaviest, I see no reason why grayling may not be 

 habituated to such a temperature — coolness being 

 generally favourable to their existence. But see, the 

 fog which had filled the valley and hid the mountains 

 from our sight is clearing away, and I fear it will be 

 a hot day. Before the sun becomes too bright is 

 the best time for fishing, in such a day as this. As 

 soon as the fog is fairly off, the water-flies will begin 

 to appear, and fish to sport. 



PHYS. — I see the fog has already disappeared from 

 the deep water in the meadow, where, I suppose, the 

 warmth of the air, from the considerable mass of the 

 water, is greater ; and which is further removed from 

 the hills sending down currents of cold air, from the 



