THE FRESH-WATER LOCHS OF SCOTLAND. 
35 
Feet. 
Acres. 
Per cent. 
0to25 
32 
39 
25 „ 50 
40 
48 
Over 50 
11 
13 
83 
100 
Temperature Observations . — A reading at the surface at the north end of 
the loch, on commencing the survey on September 11, 1902, gave 58°*6 
Fahr., while a series taken at 3.30 p.m., in the deepest part of the loch, gave 
the following results : — 
Surface ... 
10 feet ... 
25 „ ... 
57°-2 Fahr. 
57°*0 „ 
56°-0 „ 
55°-5 „ 
These observations indicate a total range of temperature throughout the 
body of water amounting to 3°*1, no very decided fall being observed 
beneath the surface, but the difference of nearly 1|° between the two 
readings at the surface is noteworthy. 
Loch Duartmore (see Plate XIII.). — Loch Duartmore is a small, irregular 
loch, trending almost east and west, and over a quarter of a mile in length. 
Its waters cover an area of about l-3 acres, while, since it receives the 
overflow from Lochs Allt na h-Airbhe and Eucail, its drainage area is very 
large — about 11| square miles, or more than 550 times greater than the 
area of the loch. The maximum depth of 22 feet was observed near the 
east end of the loch. The volume of water is estimated at 3 million cubic 
feet, and the mean depth at nearly 6 feet. The loch was surveyed on 
September IJ, 1902, when the elevation of the lake-surface was found 
to be 81*5 feet above the sea ; this was 4 feet lower than the level of Loch 
Eucail, and 38 feet lower than that of Loch Allt na h-Airbhe. 
Loch Duartmore is on the whole very shallow, the area of the lake- 
floor covered by less than 10 feet of water being about 12 acres, or 92 per 
cent, of the total area. Only in two places were depths extending 10 feet 
recorded : (1) at the extreme eastern end, where soundings in 10 to 22 feet 
were taken, and (2) off the northern shore, near the middle of the loch, 
where soundings in 12 and 16 feet were taken, the last-mentioned only 
about 20 feet from the shore, indicating a steep slope in this position. 
Some of the bays are filled with reeds. Temperatures taken in the deep 
part at the east end, at 2 p.m. on the date of the survey, gave 55°*0 Fahr. 
at the surface and 54°*6 at a depth of 17 feet. 
In the ten lochs included in the following table 994 soundings were 
taken ; the aggregate area of water surface is 3*35 square miles, so that 
the average number of soundings per square mile of surface is 296. 
The aggregate volume of water contained in the lochs is estimated at 6679 
millions of cubic feet. The area drained by these lochs is over 59 square 
miles, or nearly 18 times the area of the lochs. 
