THE FRESH-WATER LOCHS OF SCOTLAND. 
151 
was found to be 214*8 feet above sea-level. The highest drift-mark 
observed was 4^ feet above the level of the loch on September 12, 1902. 
Temperature Observations. — Temperature observations taken in 
Loch Assynt showed very little variation in the temperature of the 
surface water during the week occupied by the survey, the highest 
reading recorded being 55°*0 F. at 10 a.m. on September 12, towards 
the east end of the loch, and the lowest 53°*6 at 10 a.m. on the 16th, 
also near the east end. Beneath the surface the fall of temperature 
was also small, as shown by the following serial observations taken at 
noon on September 16, to the north of Garbh Dhoire : — ■ 
Surface ... ... .. ... ... ... .. 5.S°7 Fahr. 
50 feet ... ... ... ... ... ... 53° *5 ,, 
150 „ 52°*7 ,, 
240 „ 52°*0 ,, 
The range of temperature from surface to bottom was thus only 1°*7, 
and the extreme range observed throughout the whole body of water 
was only 3°*0. 
Loch Leitir Easaich (see Plate XXXV.). — Loch Leitir Easaich (or 
Letteressie) lies immediately to the west of, and at a slightly higher 
level than. Loch Assynt, into which it flows by a stream only a few 
yards in length. The ground around it is low. The waterfall at its 
western end, from which the loch derives its name, is very fine. Loch 
Leitir Easaich is considerably over half a mile (or about 1100 yards) in 
length, the maximum breadth being two-fifths of a mile (or about 700 
yards), and the mean breadth about one-eighth of a mile (or about 230 
yards), or 21 per cent, of the length. Its waters cover an area of about 
62 acres, and it drains an area thirty-three times greater, or 2| square 
miles. Nearly 30 soundings were taken, the maximum depth observed 
being 70 feet. The volume of water is estimated at 44,909,000 cubic 
feet, and the mean depth at 20 feet, or 28| per cent, of the maximum 
depth. The loch is extremely irregular in outline, the main body 
trending north and south, with an arm running in an easterly direction 
towards Loch Assynt. The maximum depth observed in this arm was 
31 feet, separated by shallower water from the deep basin in the main 
body of the loch, where there is a small area exceeding 50 feet in depth 
towards the western shore. The areas between the contour-lines, and 
the percentages to the total area of the loch, are as follows : — 
0 to 25 feet 36 acres 68*8 per cent. 
25 „ 50 „ 22 „ 23*6 
Over 50 ,, 4 ,, 7’6 ,, 
62 „ 
100*0 
