30 Proceedings of the Royal Society 
at 210 feet, 41°T ; at 480 feet, close to the bottom, 41 o, 0 Again, on 
Loch Katrine in 1814, fonr days earlier than in 1812, he found 
near the surface, 56° # 4; at 180 feet, 41 0, 9; at the bottom, 41 0, 3. On 
Loch Tay, in August 1812, he found at the surface, 57 0, 2; at 210 
feet, 43°*2 ; at the bottom, 420 feet, 41°*9. These results, if we 
could only know exactly how they were obtained, are singularly 
interesting as comparative with mine, got about sixty years after- 
wards. If they be quite accurate, they indicate a bottom-tempera- 
ture decidedly below what I have always obtained; and this is 
quite intelligible under the view I have taken of the probability of 
annual change, according to the character of the preceding winter; 
for all the winters preceding the times of Mr Jardine’s observa- 
tions were uncommonly severe. Or, taking a different view of the 
facts, these comparative observations give no countenance to the 
fanciful announcement by some late meteorological alarmists, that 
the climate of G-reat Britain is undergoing progressive deterioration 
by descent of the polar ice. Accurate deep-water observations in 
our deep lakes will in time very easily test this hypothesis ; if 
Jardine’s and my own be both correct, they may denote certainly 
no deterioration, but, if any change, a slight improvement rather. 
But I have shown how the difference probably arose from a 
temporary peculiarity of the climate of each year observed. As to 
Mr Jardine’s observations, we cannot now learn exactly how he 
worked, and we can trust for their correctness only to the 
character, universally allowed him during his life, of being a 
singularly acute, exact, conscientious observer of all physical facts 
and phenomena. 
