THE FRESH-WATER LOCHS OF SCOTLAND. 223 



The bottom of Loch Clair is fairly regular, the deeper water being 

 found in the wide south-eastern portion, where there is a 50-feet basin 

 about half a mile in length, enclosing a 75-feet basin one-third of a 

 mile in length. The 25-feet area is continuous, passing to the south 

 of the larger island, between which and the southern shore a depth of 

 46 feet was found. The areas between the consecutive contour-lines, 

 and the percentages to the total area of the loch, are as follows: 



to 25 feet 58 acres 34 - 9 per cent. 



-'"> 50 38 24-4 



50,, 75 41 25-9 



Over 75 , 23 , 14'8 



160 100-0 



It will be observed that the zone between 25 and 50 feet is smaller 

 than the zone between 50 and 75 feet, indicating that the average 

 slope is steeper in the shallower zone. 



Temperature Observations. A series of temperatures taken at 4 p.m. 

 on July 24, 1902, in the deep water gave the following results : 



Surface ... 57 0< OFahr. 



5 feet 57'7 



10 ,, ... 57'2 



20 ,, 57'2 ,, 



30 , 540 



40 49'9 



50 48'7 



85 48-0 



It will be noticed that the temperature of the water between 

 5 and 20 feet was higher than that at the surface, the highest reading 

 being at 5 feet. Between 20 and 30 feet a fall of 3'2 is recorded, and 

 between 30 and 40 feet a fall of 4-l, a total fall of 7'3 in 20 feet, the 

 extreme range shown by the observations being 9-7. 



Loch Coulin (see Plate XLIX.). Loch Coulin is situated 300 yards 

 to the south-east of Loch Clair, into which it drains. Doubtless, in very 

 recent times, they formed one loch, for the ground between them is low 

 and alluvial. To the south-west and south-east rise Beinn Liath Mor 

 and Carn Breac. Loch Couliu is very much overgrown with weeds, 

 especially in the narrow north-western portion. It was surveyed on 

 July 24, 1902, the water surface being 304-6 feet above sea-level, or 

 H feet above the level of Loch Clair. 



Loch Coulin is 1J miles in length, with a maximum breadth of one- 

 third of a mile, the mean breadth being about 250 yards. Its waters 

 cover an area of 113 acres, and it drains an area 78 times greater, or 

 14 square miles. The maximum depth of 49 feet occurs near the 

 centre of the broader south-eastern portion of the loch. The volume 



