THE FRESH- WATER LOCHS OF SCOTLAND. 341 



10 and 20 feet, which is nearly equal to a fall in temperature of one 

 degree per foot of depth. Reference has elsewhere been made to the 

 large range and rapid fall of temperature observed in Lochs Monzie- 

 vaird, Achilty, and Dubh,* and the temperatures here given from 

 Loch na Beinne Baine afford another instance for comparison. 



Loch Lungard (see Plate LXXXIL). Loch Lungard (or Longart, 

 or Glasletter) lies at the head of Glen Cannich, about 5 miles to the 

 north of Loch Affric. It trends east and west, and is 1 J miles in length, 

 with a maximum breadth towards the west end of one-third of a mile, 

 whence the loch narrows gradually towards the east. The superficial 

 area is about 216 acres, or one-third of a square mile, and the area 

 draining into it is nearly 23 square miles. The maximum depth of 

 129 feet was observed in a central position, but towards the east end. 

 The volume of water is estimated at 599 million cubic feet, and the 

 mean depth at nearly 64 feet. The loch was surveyed on October 7, 

 1903, when the elevation of the lake-surface above the sea was found, 

 by levelling from bench-mark, to be 761-3 feet, which is nearly identical 

 with the level observed by the Ordnance Survey officers on October 14, 

 1867, viz. 761-2 feet. When surveyed the water was about its normal 

 level, and in floods might rise about 3 feet. 



Loch Lungard is extremely simple in conformation, the bottom 

 sloping down on all sides towards the deepest part, not the slightest 

 irregularity being indicated by the soundings, while the contour-lines 

 coincide approximately with the outline of the loch. This is shown in 

 both the longitudinal section A-B and the cross-section C-D on the 

 map. The 50-feet basin is 1J miles, and the 100-feet basin rather under 

 a mile, in length, and they are comparatively wide, so that the loch is 

 of a flat-bottomed character, as is shown by the following table, giving 

 the areas and percentages between the contour-lines : 



to 50 feet 87 acres 40 per cent. 



50,, 100 81 38 



Over 100 48 22 



216 100 



Temperature Observations. The following series of temperatures, 

 taken at 2 p.m. on the date of the survey in the deepest part of the 

 loch, indicates a range of only l-2 Fahr. throughout the body of 

 water : 



Surface 49 '2 Fahr. 



25 feet 49-0 



50 48-8 



125 48-0 



* See p. 276. 



