THE FKESH-WATER LOCHS OF SCOTLAND. 
59 
very much depressed. It is nearly 4 miles in length, with a maximum 
breadth of three-quarters of a mile, and a mean breadth of one-third of a 
mile. Its waters cover an area of about 851 acres, or 1| square miles, and 
it drains an area of 41 square miles. The maximum depth of 206 feet 
was observed at the widest part of the loch, at the junction of the two 
limbs of the V. The volume of water is estimated at 2183 millions of 
cubic feet, and the mean depth at 59 feet. The loch was surveyed on 
August 21 and 22, 1902, when the elevation was found to be 129*0 feet 
above the sea, nearly identical with that determined by the Ordnance 
Survey officers on July 29, 1870, viz. 129*2 feet. The range in level is 
4 to 5 feet, the water being lower than usual for the season at the time 
of the survey, and might rise 3 or 4 feet higher, and fall a foot lower. 
Loch Damh is complex in conformation, there being three 25-feet 
basins separated from each other by shallower water. The northern basin 
is unimportant, with a maximum depth of 34 feet. The southern basin is 
of simple form, over three-quarters of a mile in length, and encloses a 
100-feet basin over half a mile in length, having a maximum depth of 
135 feet. The central basin is the largest and deepest, being 2J miles in 
length, and enclosing towards its southern end a small 200-feet basin, 
elliptical in form, and nearly a quarter of a mile in length. At the 
northern end of this central basin the 50-feet contour is irregular, shallow 
water extending towards the middle of the loch, and approaching very 
close to a small area slightly exceeding 100 feet in depth. Here a sound- 
ing in 42 feet was recorded less than 30 yards from one in 115 feet, giving 
a gradient of nearly 1 in 1. The shore-slopes to the east of the 200-feet 
basin are fairly steep, a sounding in 84 feet having been taken about 
40 yards from shore, and one in 134 feet about 90 yards from shore. 
Temperature Observations . — Serial temperatures were taken in the 
deepest part of the loch on August 21, and in the southern basin on 
August 22, with the following results : — 
Depth. 
Central basin. 
5.30 p.m., Aug. 21, 1902. 
204 feet. 
Southern basin. 
10.45 a.m., Aug. 22, 1902. 
127 feet. 
° Fahr. 
« Fahr. 
Surface 
56-5 
56-8 
10 feet 
56-5 
— 
30 „ 
— 
i 56-2 
50 „ 
56-0 
I 55-1 
100 „ 
48-5 
i 48-1 
120 „ 
— 
I 48-0 
150 „ 
43-1 
— 
180 „ 
42-2 
— 
200 „ 
42-2 i 
— 
These observations show a range of 14°*6 Fahr., the superficial layers 
of water down to 50 feet being nearly uniform in temperature, while 
between 50 and 100 feet there was a fall of 7° and 7^^°. In the deepest 
part of the loch there was a further fall of 5J° between 100 and 150 feet. 
