of Edinburgh, Session 1885-86. 
407 
wards most rapidly in the first half of the month of October. As 
the winter progresses heat leaves the water so rapidly by the sur- 
face that conduction downwards is checked and the deeper waters 
derive but very slight benefit from the summer heat at the surface. 
Observations on 18 th August 1885. — These observations were 
confined to the Tarbet basin, and were only carried to a depth of 
30 fathoms. The weather was perfect for sounding operations, 
being quite calm, so that the steam launch, which was used for the 
work, remained in position without trouble. The sun was very 
Table I. — Observations in Loch Lomond, 15 th October 1885. 
Loeality, j 
Rowar- 
dennan. 
Row- 
creeshie. 
Culness. 
Rob Roy’s 
Cave. 
Miles from Bal- ) 
loch Pier, } 
9 
10 
12* 
15 
<D 
U . 
-M 4-> 
d Cl, 
Si 
Depth at Station, 
25 
70 
100 
60 
<D .2 
Hour of day, 
noon. 
3.80 p.m. 
1 P.M. 
2 P.M. 
g o 
No. of Station, . 
1 
2 
3 
4 
S3 
fcH 03 
03 
«4-l 
Depth. 
Fathoms. 
No. of 
Thermo- 
meter. 
Temperature (Fahr.). 
Range c 
at th< 
0 
57°*5 
58 -7 
58-4 
o 
57-7 
1-2 
5 
21 
56*75 
56-2 
56-3 
55-5 
1-25 
10 
9 
56-0 
55-75 
54-3 
53-45 
2-55 
15 
23 
49-45 
48-85 
47-95 
50-0 
2-05 
20 
47 
44-5 
45-0 
45-2 
45-8 
1-3 
25 
79 
43-35 
43-85 
44-0 
43-8 
0-65 
30 
80 
42-95 
43-35 
43-0 
0-4 
0 to 30 mean, 
50-90 
4974 
1 
49-8 1 
0-35 
Steepest 
f Degs. 
-{ per fm. 
f Depth, 
} 1-31 
1-38 
1-26 
0-84 
Gradient, 
) 
13 
13 
12 1 
17 
powerful all day, and its heating effect may be judged from the 
fact that at 10 a.m. the surface water in the channel off Cam- 
stradden was 58°*9, and at 5.30 p.m. in the same position it was 
62 0, 6 F., indicating a rise of 3° -7 in the course of the day. As an 
assistance to finding the positions of the stations, I give the distance 
in nautical miles in a straight line from Balloch pier ; as a rule, they 
were made in the deepest part of the loch in the locality. 
