402 BATHYMETRICAL SURVEY OF 



mile in length, and one-ninth of a mile in greatest breadth. It is only 

 about 8 acres in area, and drains an area of over 100 acres. Its volume 

 is 2 millions of cubic feet, twice that of Loch nan Losganan. It drains 

 by a small burn into the river Coiltie. The basin is simple, with 

 evenly sloping sides, and the deepest sounding of 18 feet almost in the 

 centre. 



Loch Laide (see Plate XCII.) is a little shallow round loch, 

 measuring just about one-third of a mile in diameter, lying at a con- 

 siderable elevation among the hills to the west of Loch Ness, near its 

 northern end, above Abriachan, and about 1J miles distant. It is 

 surrounded by moorland and low hills, rising on the south side nearly 

 600 feet above the loch (Cam an Leitire, 1424 feet), within a distance 

 of half a mile. There is no bench-mark nearer to the loch than the 

 summit of this hill. On August 4, 1869, the Ordnance Survey officers 

 found the height above sea-level to be 859-8 feet. 



The superficial area of Loch Laide is about 39 acres, and it drains an 

 area of 1^ square miles. It has a volume of water of 9 millions of cubic 

 feet, only two lochs in the Ness basin (Lochs Dubh. and nan Losganan) 

 being less in volume. It is fed chiefly by one small burn, rising some 

 2 miles to the south-west, and the overflow is carried by the Allt Loch 

 Laide into Loch Ness at Abriachan. The bottom of Loch Laide is very 

 uneven. The gre'atest depth, 9 feet, is found close to the east shore. In 

 the centre the depth is only 4 feet, and other soundings of 3 and 4 feet 

 are found far out. There are low islands near shore to the south and 

 west. The mean depth is just over 5 feet, or fully half the maximum 

 depth. 



The surface temperature on May 20, 1904, was 52-3 Fahr. ; at 5 

 feet, 51-7; and at 8 feet, 51-3. 



Loch Tarff (see Plate XCL). Loch Tarff is a beautiful loch of 

 triangular form (see Fig. 62) lying high among the hills to the east of 

 Loch Ness, from which it is about a mile distant, and 3 miles north-east 

 of Fort Augustus. There are several large and small islands, some of 

 which are covered with trees. Rocky hills rise on all sides, but to no 

 great height above the loch in the immediate neighbourhood. Beinn a' 

 Bhacaidh (1813 feet) on the north is 850 feet above the loch. The high 

 mountain range, culminating in Corrieyairack, is more distant on the 

 south-east. The outline is almost an equilateral triangle. The shores 

 are undulate. The large Eilean Ban is close to the shore on the north- 

 east. On April 25, 1903, the elevation of the lake-surface was 956*2 

 feet above the sea, almost identical with that observed by the Ordnance 

 Survey officers on July 17, 1866, viz. 956'3 feet. The greatest diameter 

 measured from north-west to south-east exceeds two-thirds of a mile. 

 The maximum breadth, taken at right angles to the line of greatest 



