TEMPERATURE OF SCOTTISH LAKES 
By E. M. WEDDERBURN, W.S. 
History of Temperature Observations in Scottish Lakes 
Scotland holds an honourable position in the history of the rise 
of Limnology as a science, and only yields the first place to Switzer- 
land in this respect. 
The first observations on the temperature of the water in deep 
lakes were made by Saussure, and the careful manner in which they 
were made is described by him in his Voyages dans les Alpes^ 1779- 
1796. The first observations on the temperature of Scottish lakes 
were not much later, for in the years 1812 and 1814 Mr James 
Jardine, C.E., carried out series of observations at different depths 
in Loch Tay, Loch Katrine, and Loch Lomond, which were published 
by the late Dr Alex. Buchan in 1872.^ These observations were also 
described by Sir John Leslie in 1838 in his Treatise on Vai^ious 
Subjects of Natiiral and Chemical Philosophy (Edinburgh, 1838, p. 281), 
and in the article "Climate " by him in the eighth edition of the Encyclo- 
pcedia Bi-itannica (vol. vi. p. 777), where he expressed the view (now 
shown to be erroneous) that the seasonal variation of temperature in 
deep lakes was limited to fifteen or twenty fathoms. 
As these observations were the first to be made in Scotland, it may 
be of interest to quote Sir John Leslie's account of them, especially 
as it shows that, although one of the earliest writers on lake tempera- 
tures, he had grasped the essential elements of the subject : — 
" But the rays which fall on seas or lakes are not immediately 
arrested on their course ; they penetrate always with diminishing 
energy, till, at a certain depth, they are no longer visible. This depth 
depends without doubt on the clearness of the medium, though 
probably not one-tenth part of the incident light can advance five 
fathoms in most translucid water. The surface of the ocean is not, 
therefore, like that of the land, heated by the direct action of the 
^ Proc. Roy. Soc. Edin., vol. vii. p. 791. 
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