THE FBESH- WATER LOCHS OF SCOTLAND. 155 



Loch na Cuaich (see Plate LVII.) lies on the east side of Glen Truim, 

 about 5 miles north-east from the head of Loch Ericht. Stac Meall na 

 Cuaich rises to a height of 3000 feet immediately to the east of the loch. 

 Trending in a north-east and south-west direction, the loch is nearly a 

 mile in length, with a maximum breadth of a quarter of a mile near the 

 south-west end, whence it narrows gradually towards the opposite end. 

 The superficial area is about 116 acres, and the drainage area exceeds 

 2^ square miles. The maximum depth of 85 feet was observed approxi- 

 mately near the centre of the loch, but towards the south-west end. The 

 volume of water is estimated at 214 million cubic feet, and the mean depth 

 at 42 ^ feet. The loch was surveyed on May 12, 1904, and the elevation 

 from spot-levels was estimated to be about 1296 feet above the sea. The 

 loch forms a simple basin, the contour-lines coinciding approximately 

 with the outline, but approaching closer to the eastern than to the western 

 shore, indicating a steep slope on the eastern side ; in fact, in one place a 

 sounding in 50 feet was taken about 50 feet from the eastern shore, equal 

 to a gradient of 1 in 1. The surface temperature was 41'8 Fahr. 



Loch an Duin (see Plate LVII.) lies about 7 miles to the east of the 

 head of Loch Ericht, and 5 miles south-east from Loch na Cuaich, at an 

 elevation of 1600 feet among the mountains, which rise on the west to 

 2707 feet, and on the east to 2844 feet, above the sea, the lower slopes 

 forming steep screes of small material. The shores are all stony, and the 

 outflow to the north is among stones. Loch an Duin drains northward 

 into Loch Bhradain, and thence into Loch an t-Seilich. It is a long and 

 narrow loch, trending almost north and south, and over a mile in length, 

 the maximum breadth being less than one-fifth of a mile. The superficial 

 area is about 102 acres, and the drainage area exceeds a square mile. The 

 maximum depth of 102 feet was observed in the middle of the loch. The 

 volume of water is estimated at 134 million cubic feet, and the mean depth 

 at over 30 feet. The basin is simple, the deeper water occupying a central 

 position, where the contour-lines approach close to the shores, showing 

 that the sides are very steep ; in one place off" the eastern shore a sounding 

 in 45 feet was taken about 50 feet from shore. The 25-feet basin is rather 

 more, and the 50-feet basin rather less, than half a mile in length, the two 

 ends of the loch being comparatively shallow, about two-thirds of the lake- 

 floor being covered by less than 25 feet of water. The deep, central part 

 is flat-bottomed, with the U-shaped section characteristic of ice-eroded 

 basins. The loch was surveyed on October 14, 1904, but the elevation 

 could not be determined; from spot-levels it was estimated to be about 

 1 590 feet above the sea. A gravelly beach was seen at places 2 feet above 

 the water. Temperatures taken in the position of the deepest sounding 

 showed that the water was practically uniform in temperature throughout, 

 the reading at the surface being 44'2 Fahr. ; while at 50 and 100 feet 

 identical readings of 44 7< were recorded. 



