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 Rev. 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 suffered 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 difference 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 different physical conditions, show widely different 
temperatures with minimias much as 10° apart. It 
* Twenty-first Report, Fishery Board for Scotland, II. pp. 76 
and 82. 
