THE FRESH- WATER LOCHS OF SCOTLAND. 
119 
soundings taken giving a depth of 9 feet. The shores are mostly of rock, 
with stony debris, sandy gravel covering the eastern shore at the narrow 
part near the north end. The temperature of the surface water on the 
date of the survey varied from 58°-5 to 60°*5 Fahr., a reading at a dei>th 
of 8 feet giving 58°*0. 
Loch Ken (see Plate XLV.). — Loch Ken is the largest in the basin, 
trending from north- west to south-east, the northern end being over a mile 
south of New Galloway, and the southern end about 7 miles north of Castle 
Douglas, the confluence of the Black Water of Dee with the river Dee being 
looked upon as the southern limit of Loch Ken. The length exceeds miles, 
the maximum breadth across the centre of the loch at the entrance of the 
Dullarg burn being about half a mile, and the mean breadth over a quarter 
of a mile. The waters of the loch cover an area of about 867 acres, or 1| 
square miles, and the area draining into it is very large, extending far to 
the north and west, and including the other lochs within the basin dealt 
with in the preceding pages, as well as a few lochs which were not 
surveyed. The total drainage area thus amounts to about 282 square 
miles. The maximum depth of 62 feet was recorded about a mile from the 
upper end. The volume of water is estimated at 792 millions of cubic 
feet, and the mean depth at 21 feet. The loch was surveyed on July 
14, 1903, the elevation being 142*0 feet above the sea. 
The floor of Loch Ken is irregular, there being six separated areas 
where the depth exceeds 25 feet, and two areas where the depth exceeds 
50 feet. The 20-feet contour would be continuous almost from end to end, 
except for a slight break opposite the entrance of the Arvie burn, where 
the deepest sounding was 19 feet. The deepest basin occupies the wide 
portion at the head of the loch, where there is a 25-feet area over 1^ miles 
in length, enclosing a 50-feet area over three-quarters of a mile in length, 
the maximum depth of 62 feet having been observed towards the eastern 
shore. The second 50-feet area, based on a sounding in 52 feet, lies less 
than a mile from the foot of the loch, occupying a central position in a 
25-feet area three-quarters of a mile in length. To the south of this area 
the water deepens again to 31 feet, and near the entrance of the Black 
Water of Dee another sounding in 33 feet was taken. Of the entire lake- 
floor 71 per cent, is covered by less than 25 feet of water. 
Temperature Observations . — Serial temperatures taken in the deepest 
basin showed a gradual decrease of temperature, the total range from 
surface to bottom being 4°*7 Fahr., as follows : — 
Surface 
25 feet 
30 „ 
35 „ 
40 „ 
55 „ 
60°-2 Fahr. 
59°*5 „ 
58°*5 „ 
57°-5 „ 
56°*5 „ 
55°*5 „ 
Expansions of the River Dee (see Plate XLV.j. — The expansions of the 
