105 
1908-9.] Temperature Observations in Loch Garry. 
in May the rate at which heat' enters the lake begins rapidly to increase, 
and at the same time the temperature gradient in the lake increases, 
indicating that when the rate of heat-supply is sufficiently great, wind 
currents are not sufficiently strong to produce a thorough mixing of the 
water. Increasing differences of density also tend to make wind-produced 
currents less far-reaching, and the temperature gradient in the lake rapidly 
increases. 
On 6th May the temperature at the surface and 200 feet was respectively 
44'5° and 41 '2°, there having been little variation in the bottom temperature 
during the previous ten days. Owing to stormy weather no observations 
were made on the 7th, but on the 8th the bottom temperature had risen to 
42° — a rise of *8° — showing the influence of currents produced by winds. 
A more marked case occurred about a week later. On 15th May the 
surface temperature was 46'3° F., and at the bottom 42'3° ; again there 
had been very little variation in the bottom temperature. On the 16th 
and 17th the wind was very strong and no observations could be made, but 
on the 19th it was found that the bottom temperature had risen l - 7° to 
44’0°. There was a continuance of moderately strong winds, with the result 
that the bottom temperature had risen to 44 - 5° by 22nd May, and to 45‘0° by 
the 27th. Variable winds were experienced till the 5th of June, when the 
bottom temperature was only 45*2°, showing little variation for the previous 
nine days, but the wind increased on the 5th, and observations on 6th June 
showed a bottom temperature of 45'5°, and on the 10th 46'0°. 
As will be seen in Table II., about the middle of June the lake, instead of 
gaining in heat, began to lose it. The result is the formation of a slight 
temperature discontinuity. 
Table IV. 
Observations at Centre of Loch Garry , June 1908. 
6th. 
8tli. 
9th. 
10th. 
11th. 
12 th. 
13 th. 
15th. 
16th. 
17th. 
18th. 
19th. 
20th. 
Surface 
56-8 
52-2 
53T 
52-8 
52-8 
52-0 
51-9 
51-8 
51*4 
51-9 
52-0 
52-2 
52-0 
25 
50-5 
51-5 
50-0 
52-0 
5T9 
52-0 
51-8 
51-5 
5T2 
51-3 
51T 
51-4 
5T5 
50 
48*0 
50-9 
48-9 
48-7 
49-0 
50-4 
51-0 
51-3 
51T 
51-0 
50-5 
50-5 
50-9 
75 
47-0 
49-0 
47*0 
47-0 
46-7 
47-0 
46-8 
46-7 
47*6 
47-0 
47-6 
47-5 
47-3 
100 
46-0 
45-9 
46-4 
46-2 
46-2 
46-4 
46-3 
46-3 
46*0 
46-3 
46-2 
46-4 
46-2 
150 
45-8 
45*7 
45-9 
46-0 
46-0 
46-0 
46-0 
46-0 
46-0 
46*0 
46-0 
46-0 
46-0 
200 
45-5 
45*5 
45-8 
46-0 
45-8 
459 
45-9 
46-0 
46-0 
46-0 
46-0 
46-0 
46-0 
Table IV. gives some of the observations made at this time, and they 
show the gradual appearance of a discontinuity between 50 and 75 feet, 
