64 BATHYMETEICAL SUKVEY OF 



Leitreach. The loch trends nearly north and south, and is irregular in 

 outline, two-thirds of a mile in length, and over a quarter of a mile 

 in maximum breadth, the superficial area being about 78 acres, while the 

 area draining into it is nearly 2 square miles. The maximum depth of 44 

 feet was found towards the lower (northern) end, in the vicinity of the 

 two islands situated in the lower half of the loch. The volume of water 

 is estimated at 56 million cubic feet, and the mean depth at 16 J feet. 

 The loch was surveyed on October 25, 1904, when the elevation was 

 found to be 1242'6 feet above the sea, as compared with 1242-3 feet 

 determined by the officers of the Ordnance Survey on August 6, 1867. 

 Serial observations taken in the deepest part of the loch showed that the 

 temperature of the water was practically uniform, the reading at the 

 surface being 46-4 Fahr., and at 25 feet and at the bottom 46-2. 



Loch Anna (see Plate XXIII.). Loch Anna lies about 1J miles from 

 the northern shore of Loch Alsh at Ardelve. It trends in a north-west 

 and south-east direction, and is one-third of a mile in length, the super- 

 ficial area being about 24 acres, and the drainage area about half a square 

 mile. The volume is estimated at 13 million cubic feet, and the mean 

 depth at nearly 13 feet. The wide northern portion contains the deepest 

 basin, the maximum depth of 27 feet being found close to the north- 

 eastern angle of the loch, while at the upper end there is a small basin 

 based on soundings in 20 and 21 feet. The loch was surveyed on October 

 24, 1904, the elevation being estimated from spot-levels at about 1040 feet 

 above the sea. The temperature of the water was found to be uniform, 

 readings at the surface and at a depth of 20 feet giving 44*6 Fahr. in 

 each case. 



