THE FRESH-WATER LOCHS OF SCOTLAND. 
251 
corresponding approximately with the level of the sea), and is flat- 
bottomed in character, as shown in cross-section C-D on the map. 
The areas between the consecutive contour-lines drawn in at equal 
intervals, and the percentages to the total area of the loch, are as 
follows : — 
0 to 25 feet 
187 acres 
44T per cent. 
25 „ 50 „ 
111 „ 
260 
50 ,, 75 ,, 
88 „ 
20-9 
75 „ 100 „ 
20 „ 
4-8 
Over 100 ,, 
18 „ 
4-2 „ 
424 ,, 
100-0 
T emperature Observations . — ^The temperature of the surface water 
in Loch Eilt during the two days spent on it varied from 58° to 60° 
Fahr. On July 10, 1902, three series of temperatures were- taken 
beneath the surface, one in each of the three basins into which the loch 
is divided, with the following results : — 
Depth in feet. 
Loch Eilt (eastern 
basin). 
July 10, 1902, 
2’30 p.m. 
Loch Eilt (central 
basin). 
July 10, 1902, 
3'30 p.m. 
Loch Eilt (western 
basin). 
July 10, 1902, 
5 p.m. 
° Fahr. 
° Fahr. 
“ Fahr. 
Surface. 
58-0 
58-1 
60-0 
10 
58-0 
58-1 
60-0 
20 
58-0 
58T 
60 0 
27-5 
55-7 
57-7 
60-0 
35 
52-8 
53-6 
59-7 
50 
50-7 
52-8 
54-8 
75 
53 0 
100 
1 
51-0 
These series show a constant temperature down to 20 feet in each 
case, but the water in the deep western basin was 2° warmer than in 
the other two basins. Beyond the depth of 20 feet, again, the tem- 
perature was about 2° higher in the western basin than in the central 
basin, and 2° higher in the central basin than in the eastern basin, so 
that at a depth of 100 feet in the western basin the temperature was 
rather higher than at a depth of 50 feet in the eastern basin. The 
water in the western basin was warmer at all depths than that in the 
central basin, and in the central basin than in the eastern basin. To 
explain this peculiar distribution of temperature in the waters of Loch 
Eilt on the afternoon of July 10, 1902, the weather conditions during 
the few preceding days must be taken into account. The wind had 
been blowing strong from the north-east from the 3rd till the afternoon 
of the 9th. Rain commenced to fall about 6 a.m. on the 9th, and 
continued till about 8 a.m. on the 10th, so that during the twelve hours 
from 9 p.m. on the 9th to 9 a.m. on the 10th the surface of the loch rose 
