THE FRESH- WATER LOCHS OF SCOTLAND. 225 



The temperature was found to be constant from the surface to a 

 depth of 15 feet, thence the temperature fell 4 to the bottom in 40 

 feet. 



Loch Tollie (see Plate XLVII.). Loch Tollie is situated 1J miles to 

 the west of the lower end of Loch Maree, and drains into its north- 

 western arm. The ground immediately surrounding the loch is low, 

 though Meall Airidh Mhic Criadh to the south-west, and Creag Mhor 

 Thollie to the south-east, rise to over 1100 feet. The loch is roughly 

 elliptical in outline, the major axis having an east and west direction. 

 One of the islands near the northern shore was for some time a strong- 

 hold of the McLeods. 



Loch Tollie was surveyed on July 29, 1902, the elevation of the lake- 

 surface being 387 - feet above sea-level ; when visited by the Ordnance 

 Survey officers on November 13, 1869, the level was found to be 387-7 

 feet. The water must at one time have stood at a higher level, for at 

 the east end, where the stream leaves the loch, there are the remains of 

 a dam (now fast disappearing), which held up the water for supplying 

 a mill farther down the burn. 



Loch Tollie is under a mile in length, with a maximum breadth of 

 about 800 yards, the mean breadth being about 500 yards. Its waters 

 cover an area of about 169 acres (a quarter of a square mile), and it 

 drains an area eight times greater, or 2 square miles. The maximum 

 depth of 86 feet was observed in the centre of the loch off the mouth 

 of the Allt Loch Laraig. The volume of water is estimated at 244 

 millions of cubic feet, and the mean depth at 33 feet. The breadth of 

 the loch at the position of the deepest sounding is 27 times the depth. 

 The shore development is small (I'll), and the insulosity 0'002. The 

 deeper water occurs in the western part of the loch, though the 25-feet 

 area sends a narrow tongue into the eastern part. The 75-feet area 

 in the centre of the loch is small, with a narrow tongue extend- 

 ing towards the northern shore. The areas between the consecutive 

 contour-lines, and the percentages to the total area of the loch, are 

 as follows : 



to 25 feet 81 acres 48'0 per cent. 



25,, 50 43 25-6 



50,, 75 35 20-6 



Over 75 , 10 , 58 



169 ,, 100-0 



Temperature Observations. The following series of temperatures 

 was taken in the centre of the loch at 6 p.m. on July 29, 

 1902: 



