THE FRESH- WATER LOCHS OF SCOTLAND. 
93 
the length. Its waters cover an area of about 111 acres, or over one- 
sixth of a square mile, and it drains an area nearly 30 times greater, 
or over 5 square miles. Nearly 60 soundings were taken, the maximum 
depth observed being 95 feet. The volume of water is estimated at 
189,623,000 cubic feet, and the mean depth at 39 feet, or 41 per cent, 
of the maximum depth. The length of the loch is 53 times the maximum 
depth and 130 times the mean depth. The loch is of simple conforma- 
tion, and, on the whole, comparatively deep, only half a dozen soundings 
under 10 feet being recorded close to the shore. Off the northern shore, 
towards the west end, the slope of the bottom is very steep, soundings 
of 31 feet and 44 feet having been taken about 80 and 100 feet from the 
shore respectively; this is equal to a slope of 1 in 2*3 to 2-6. The 
eastern end, and south-eastern portion of the loch around the island, are 
comparatively shallow. The 25-feet basin is about three-quarters of a 
mile in length, stretching from quite close to the west end to within 
one-sixth of a mile from the east end. The 50-feet basin is nearly half 
a mile in length, and the 75-feet basin, occupying the western half of 
the loch, is over one-third of a mile in length. The maximum depth 
of 95 feet was observed in two places approximately near the centre of 
the wide western portion of the loch. The area of the lake-floor 
covered by less than 25 feet of water is about 50J acres, or over 45 per 
cent, of the total area of the loch; that covered by water between 25 
and 50 feet in depth is about 21 J acres, or over 19 per cent. ; that 
covered by water between 50 and 75 feet in depth is about 19 acres, or 
17 per cent. ; and that covered by more than 75 feet of water is about 
20J acres, or over 18 per cent, of the entire area of the loch. The flat- 
bottomed character of the deep western portion of the loch is well 
brought out by a comparison of the last two percentages, while the high 
percentage of the bottom covered by less than 25 feet of water is due to 
the comparatively large shallow area in the south-eastern and eastern 
part of the loch. Loch Daimh was surveyed on May 26, 1903, but the 
level of the surface of the water above the sea could not be determined. 
T emperature Observations . — The temperature of the surface water 
on commencing the survey at 9.30 a.m. on May 26, 1903, was 51°-0 
Fahr., and a series of temperatures taken in the deepest part of the 
loch gave the following results : — 
Surface 
10 feet 
25 „ 
50 „ 
90 ,, 
50° -3 Fahr. 
47° -0 „ 
44°-0 „ 
43° -5 „ 
43° 0 „ 
The range in the temperature of the water from surface to bottom was 
thus 7°*3. The fall of temperature from the surface to a depth of 
10 feet amounted to 3°*3, and that between the depths of 10 and 25 feet 
amounted to 3°-0, and below 25 feet the fall amounted to 1°*0. 
