thp: fresh-water lochs of Scotland. 
303 
occupies a central position. The offshore slope is in some places very 
steep, and the average slope outside the 25-feet contour is steeper 
than in the deeper water between 25 and 50 feet, as shown in the 
following table giving the areas between the contour-lines, and the 
percentages to the total area of the loch : — 
0 to 25 feet 77 acres 
25 „ 50 „ 87 ,, 
Over 50 ,, 9 ,, 
173 „ 
44 5 per cent. 
50-6 
100-0 
The surface temperature on August 23, 1902, at 12.30 p.m., was 
57° Fahr. ; and on August 25, at 11.45 a.m., 56°. 
Loch Migdale (see Plate LXX.). — Loch Migdale is situated close to 
the northern shore of the Dornoch firth, and less than a mile from Bonar 
Bridge at the head of that firth. It contains trout and pike, and the 
surrounding scenery is very fine, a conspicuous hill called Migdale Rock 
rising off the north-eastern shore. The island at the west end of the 
loch is artificial, composed of large and small stones; a crossing passes 
from the western shore to the island, and was covered by a foot of water 
at the time of the survey. The loch trends in a north-west and south- 
east direction, and is nearly 2 miles in length, with a maximum width 
of nearly half a mile towards the north-west end, the loch narrowing 
gradually towards the opposite end. Its waters cover an area of 
about 260 acres, and it drains an area of about square miles. The 
maximum depth of 49 feet was observed rather nearer the north-west 
than the south-east end. The volume of water is estimated at 242 
million cubic feet, and the mean depth at over 21 feet. Loch Migdale 
was surveyed on September 24, 1902, when the elevation of the lake- 
surface was found to be 113-6 feet above the sea; when visited by the 
Ordnance Survey officers on November 1, 1869, the elevation was 115*1 
feet above sea-level. 
The loch forms a simple basin, with a few minor undulations of 
the lake-floor. The contour-lines approach nearer to the eastern end, 
where the Spinningdale burn flows out, the water being shallower 
towards the opposite end, with weeds growing off the northern shore, 
at the entrances of Migdale burn and Munroe’s burn. The area of the 
lake-floor covered by less than 10 feet of water is about 70 acres, or 
27 per cent, of the total area, while that covered by more than 25 feet 
of water is about 94 acres, or 36 per cent. Temperatures taken at 
6 p.m. on the date of the survey, in the deepest part of the loch, 
showed very little variation in the temperature of the water, the reading 
at the surface being 54°-9 Fahr., at 25 feet 54°-l, and at 40 feet 54°. 
