794 Proceedings of the Royal Society 
Observations of the Deep-Water Temperature of Lochs Tay , Katrine, 
and Lomond , by the late James Jar dine, Esq., G.E. 
Depth. 
Loch Tay. 
Aug. 12, 1812. 
Loch Katrine. 
Sept. 3, 1814. 
Loch Katrine. 
Sept. 7, 1812. 
Loch Lomond 
Sept. 8, 1812. 
Surface 
57°-2 
56°*8 
57°-9 
59°*5 
30 feet 
56°- 7 
60 
49°-6 
5o"-9 
90 
45°-5 
440.4 
120 
440.4 
43 V -5 
150 
43°'3 
• . . 
180 
42°*3 
210 
43°*2 
41°*5 
240 
... 
41°*7 
300 
)) 
... 
41 °* 5 
360 
... 
41°*5 
... 
420 
41°’ 9 
... 
... 
480 
;; 
4l°-7 
41°*4 
41°*7 
540 
y) 
41°*5 
600 
>> 
... 
... 
41°*5 
These results are strikingly accordant with those obtained by 
Sir Robert Christison, The difference as regards the deep- 
water temperature of Loch Lomond may he, and probably is, only 
instrumental. 
These observations were made in the summer and early autumn, 
or when the temperature of the sea and of lakes is about the 
annual maximum. Taken in connection with Sir Robert’s observa- 
sions, they warrant the conclusion that the deep-water temperature 
of Loch Lomond remains during the whole year either absolutely 
at, or very nearly at, the low figure of 42 o, 0. 
The observations also show that this is not a peculiarity of Loch 
Lomond, hut that it is also a characteristic of Lochs Katrine and 
Tay, and most probably of other deep waters. 
The mean annual temperature of the air at Loch Lomond, from 
the mean at Balloch Castle, calculated on the 13 years’ average, 
ending 1869, is 48 o, 0,* which is 6 o, 0 higher than the uniform 
deep-water temperature of the loch. The deep-water temperature 
* In this and following temperatures 0 o, 2 has been added, in order to bring 
them to the level of the loch, which is 72 feet lower than the thermometers at 
Balloch Castle. 
