THE FRESH-WATER LOCHS OF SCOTLAND. 11 



lii Loch Doine the deeper water occupies approximately the centre 

 of the loch, the deepest soundings (65 feet) being found, however, nearer 

 the eastern than the western end of the loch. The 50-feet depression 

 covers over one-third of the area of the loch, being about three-quarters 

 of a mile in length with a maximum width of over one-eighth of a mile. 

 It seems doubtful whether this 50-feet depression is not really separated 

 into a larger and smaller portion, for the narrow neck shown on the 

 map is founded upon a single sounding of exactly 50 feet. The greatest 

 depth, 65 feet, was observed in several spots situated towards the 

 eastern end of the loch. The area with depths over 50 feet is estimated 

 at 47 acres, or 35 per cent, of the entire area of the loch, while the area 

 with depths less than 50 feet is estimated at 88 acres, or 65 per cent, 

 of the area of the loch. 



Loch Lubnaig (see Plate VI.). The outflow from Lochs Doine and 

 Voil passes by the river Balvag, 5 miles in length, into Loch Lubnaig, 

 the surface of whose waters is, according to the Ordnance Survey maps, 

 405 feet above sea-level, or 9 feet lower than that of the other two lochs. 

 A consideration of the intervening ground indicates that in post-glacial 

 times these three lochs formed one single sheet of water. 



Loch Lubnaig has a total length of nearly 4 miles, following ap- 

 proximately a line drawn down the centre of the loch, with a maximum 

 width of about two-fifths of a mile. The mean breadth is nearly a 

 quarter of a mile, or 422 yards, being 6 per cent, of the length. Its 

 waters cover an area of about 614 acres (or nearly 1 square mile), and it 

 drains an area 36J times greater, or about 22,400 acres (nearly 35 square 

 miles). The total number of soundings taken in Loch Lubnaig was 

 394, the average depth of these being 20J feet, and the greatest depth 

 observed 146 feet (24 J fathoms). The bulk of water contained in the 

 loch is estimated at 1,144,000,000 cubic feet, and the mean depth at 

 42^ feet (or 7 fathoms), being 29 per cent, of the maximum depth. 

 The length of the loch is 145 times the maximum depth, and 493 times 

 the mean depth. 



Loch Lubnaig differs from the other lochs in the neighbourhood in 

 that it does not constitute a single basin. The bottom is apparently 

 very irregular ; the contour lines of depth do not follow the contour of 

 the loch, hollows and ridges alternate with each other, and in some 

 places comparatively deep water is found close to the shore, while in 

 other places shallow water extends a considerable distance from shore. 

 The loch is also, comparatively speaking, very narrow and shallow con- 

 sidering its size, nearly two-thirds of the area being under 50 feet in 

 depth. The loch may be conveniently divided into two halves, defined 

 by the central constriction in the outline of the loch at the entrance of 

 the Ardchullarie burn, where the bottom shallows and separates the two 

 principal deep depressions; the northern half trends in a north-west 



