56 SALMON1A. [SECOND DAT. 



principally of the carp kind : but the true fisherman's 

 flies, those which are imitated in our art, principally 

 belong to the northern, or at least temperate part of 

 Europe, and I believe are nowhere more abundant 

 than .in England. It appears to me, that since I have 

 been a fisherman, which is now the best part of half a 

 century, I have observed in some rivers where I have 

 been accustomed to fish habitually, a diminution of 

 the numbers of flies. There were always some seasons 

 in which the temperature was favourable to a quantity 

 of fly ; for instance, fine warm days in spring for the 

 grannam, or brown fly; and like days in May 

 and June for the alder-fly, May -fly, and stone-fly : 

 but I should say that, within these last twenty years, 

 I have observed a general diminution of the spring 

 and autumnal flies, except in those rivers which 

 are fed from, sources that run from chalk, and 

 wliich are perennial such as the Wandle, and 

 the Hampshire and Buckinghamshire rivers; in 

 these streams the temperature is more uniform, 

 and the quantity of water does not vary much. I 

 attribute the change of the quantity of flies in the 

 rivers to the cultivation of the country. Most of the 

 bogs or marshes which fed many considerable streams, 

 are drained; and the consequence is, that they are 

 more likely to be affected by severe droughts and 

 great floods the first killing, and the second washing 



