THE FRESH-WATER LOCHS OF SCOTLAND. 
107 
sonth-east is over a third of a mile, the maximum breadth being nearly 
a quarter of a mile, and the superficial area 2(3 acres, of which 67 per cent, 
is covered by less than 10 feet of water. The deeper water occupies a 
central position, the maximum depth of 15 feet being found towards the 
north-eastern shore. The volume of water is estimated at 8 million cubic 
feet, and the mean dej^th at feet, the area drained being about three- 
quarters of a square mile. The temperature at the surface and at a depth 
of 12 feet was identical on August 17, 1903, viz. 57°‘8 Fahr. 
Loch Ochiltree (see Plate XL.). — Loj3h Ochiltree lies a mile and a half 
to the east of Loch Maberry, and is nearly a mile in length from north 
to south, the maximum breadth across the centre being over half a mile, 
and the mean breadth a quarter of a mile. The superficial area is about 
156 acres, of which 74 per cent, is covered by less than 10 feet of water. 
At the northern end is a small deep basin, where the maximum depth of 
34 feet was recorded. The volume of water is estimated at 52 million 
cubic feet, and the mean depth at nearly 8 feet. Besides Loch Fynitalloch, 
the little Black Loch lying to the north drains into Loch Ochiltree, the 
total drainage area exceeding 2 square miles. The loch was surveyed 
on August 17, 1903, when the elevation was 341*1 feet above the sea, 
as compared with 341*5 feet determined by the Ordnance Survey on 
December 14, 1893. 
Temperature Observations . — Serial temperatures in the deej)est part of 
the loch gave the following results: — 
Surface ... 
10 feet . . . 
20 „ ... 
30 „ ... 
58°-5 Fahr. 
58°-0 „ 
57°-4 „ 
57°*4 „ 
The range of temperature from surface to bottom was only 1°*1, and 
this occurred between the surface and a depth of 20 feet, the readings at 
20 and 30 feet being identical. 
Castle Loch (see Plate XLI.). — The Castle Loch lies to the west of the 
Mochrum Loch, the nearest point about half a mile distant. It is slightly 
smaller than Mochrum Loch, and of less irregular form, roughly triangular, 
with the apex to the south-west. The surrounding moor is very rough, 
with much rock showing, except on the north, where smooth rounded hills 
rise, covered with grass or bracken. It measures nearly 1^ miles in length, 
from south-west to north-east, and half a mile in greatest breadth. The 
bottom is nearly flat, and the maximum depth is 11 feet. The mean depth 
is 6J feet, the area about 228 acres, or one-third of a square mile, and the 
volume 65 millions of cubic feet, a very little less than that of Mochrum 
Loch. The loch is fed by a few small burns. The outflow is by a large 
burn flowing eastward through a marshy stretch into Mochrum Loch. No 
rock was seen in the stream, but there was rock ex230sed near the outflow. 
There is rock at Castle island, and several other small islands. Besides 
