THE FRESH-WATER LOCHS OF SCOTLAND. 399 



contents amount to 62 millions of cubic feet. The drainage area, which 

 includes Loch an Staca, is 4 square miles. Beyond the burn from Loch 

 an Staca, and another from the hill (2222 feet) on the west, it receives 

 only superficial drainage. The burn Allt Bhlair flows out to the south- 

 east, and, joining that from Loch na Criche, enters the river Moriston. 

 The basin is quite simple, the deeper water nearer the south-east side, 

 and the maximum depth of 55 feet towards the north-east end. 



When surveyed on June 10, 1904, the level was found to be 1494-1 

 feet above the sea, which differs little from the level determined by the 

 Ordnance Survey officers on May 15, 1869, viz. 1494-4 feet. 



The surface temperature was 56-9 Fahr. 



Loch nam Breac Dearga (see Plate XCL). Situated on the high 

 ground to the west of Loch Ness, about 1 \ miles distant from the middle 

 part of that loch. It lies close to the west of Meall Fuarvounie (2284 

 feet high), which separates it from Loch Ness. The loch is elongate, 

 lying nearly north-east and south-west, and of irregular form, roughly 

 oblong. The surrounding moorland rises little above the loch, except 

 on the east, where the crags of Meall Fuarvounie rise close beside the 

 loch. 



This loch was locally reputed to be of great depth, or even supposed 

 to be bottomless. Though we found it to be the deepest loch in this 

 elevated tract between Glen Urquhart and Glen Moriston, its depth was 

 not remarkable, and not greatly in excess of that of Lochs Liath and an 

 Staca in the same district. It is three-quarters of a mile in length, 

 about one-fifth of a mile in greatest breadth, and one-eighth of a mile 

 in mean breadth. 



The superficial area is about 56 acres, and drains about two-thirds 

 of a square mile. It contains 60 million cubic feet of water. It is 

 drained by a burn running some 2 miles south-westward, into the Allt 

 nan Saighead (Alltsigh), which also receives the overflow of a host of 

 little lochs, which were not surveyed, and runs into Loch Ness. The 

 height above the sea was estimated at 1570 feet. 



The basin is simple, but deepest toward the upper or north end. 

 The lower portion is all under 25 feet in depth. The areas of over 

 25 feet and over 50 feet pass obliquely across the loch from south to 

 north. The 50-feet contour encloses a narrow area, about a quarter 

 of a mile long, with the deepest sounding, 70 feet, in the middle of 

 the loch, but nearer the north end. 



The surface temperature on June 1, 1904, was 52-9 Fahr. ; at 10 

 feet, 52-7 ; at 25 feet, 48-2 ; and at 60 feet, 46-2, giving a total range 

 of 6-7, the greatest fall being one of 4-5 between 10 and 25 feet. 



Loch a Vullan (see Plate CI.). A little loch of triangular form, 

 in the elevated hilly country to the west of Loch Ness, and about 



