THE FRESH-WATER LOCHS OF SCOTLAND. 107 



south-east is over a third of a mile, the maximum breadth being nearly 

 a quarter of a mile, and the superficial area 26 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 depth at 7J 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. 



LocJt Ochiltree (see Plate XL.). Loch 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 Fyntalloch, 

 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 deepest part of 

 the loch gave the following results: 



Surface 58-5 Fahr. 



10 feet 58-0 



20 ' 57'4 



30 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 XLL). 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 6^ 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 

 biirn flowing eastward through a marsliy stretch into Mochrum Loch. No 

 rock was seen in the stream, but there was rock exposed near the outflow. 

 There is rock at Castle island, and several other small islands. Besides 



