THE FRESH-WATER LOCHS* OF SCOTLAND. 
11 
In Locli 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 Luhnaig (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 
