132 THE LIFE OF THE SALMON 



fish, each unspoilt by man. In a search for a really 

 warmer river, I have been fortunate in obtaining a 

 valuable series of temperature readings from the 

 Nith, which flows into the Solway. These were 

 taken for me by Kev. Mr. Andson, of Dumfries, in 

 1902, and I am able to compare them with Tay 

 readings for the same year. In the early months of 

 the year the Nith is distinctly warmer than the Tay, 

 and the Nith is a late river, but unhappily it cannot 

 be said to be a river in which the natural supply of 

 salmon is unimpaired. The salmon fisheries of the 

 Nith district have sufi'ered much at the hands of 

 man. In this same year, however, 1902, tempera- 

 tures were taken in the river Ness, which is a well- 

 stocked early river, supplied from one of the largest 

 and deepest lochs in Scotland, and the Ness tempera- 

 ture shows a marked difierence from that of the Tay. 

 Curves have been plotted for each river,* from which 

 it is at once noticeable that while the Ness shows a 

 comparatively flat curve never falling below 42°, the 

 Tay curve at Perth shows acute inclination with a 

 minimum at freezing point (32°). 



We see therefore, from a comparison of the ascer- 

 tained thermal conditions of those rivers, that east 

 coast early rivers do not show any marked difference 

 from late west coast rivers when the selection is made 

 in Sutherland alone ; and second, that east coast 

 early rivers in different parts of the country, subject 

 to difierent physical conditions, show widely different 

 temperatures with minimi as much as 10° apart. It 



* Twenty-first Report, Fishery Board for Scotland, II. pp. 76 

 and 82. 



