EFFECTS OF RAIN AND SNOW. 21 



and thickly-inhabited counties, where access is cut off to 

 the pure springs of water ! 



As regards salmon, if I am rightly informed by a gentle- 

 man at Gloucester, who is a proprietor of twelve miles of 

 the river Severn, the grilse spawns in September and Octo- 

 ber ; the salmon in October, November and December. 

 The young fish issue from the egg in from 100 to 120 days, 

 according as the warmth of the water may have varied, 

 which at that time of the year, from cold, rain or snow, it 

 frequently does ; the process of incubation being retarded 

 in proportion to the effects produced by the nitrous quality 

 of snow-water, which reduces the temperature from 55 to 

 30, and that in a few hours ; and when a large mass of 

 snow falls into a spring- stream, it acts like salt combined 

 with snow r and freezes all before it. Oyster-beds for miles 

 are sometimes from this cause totally destroyed in one 

 night; for when this occurs all fish retire to the deeps. 

 Some streams, from this, in conjunction with other causes, 

 freeze upwards from their very beds in the shallows, and it 

 is there where most fish prefer to spawn : so that every egg 

 is directly destroyed ; but, fortunately, this extreme case is 

 not of frequent occurrence, although I have observed it in 

 more instances than one. The ice forms on the bed of the 

 stream, and rises upwards to the surface as the water reco- 

 vers its original temperature. There are parts of the Colne 

 where this can be observed. As grilse spawn so much 



