16 
BATHYMETRICAL SURVEY OF 
number of soundings taken in Loch Ard was 308, the maximum depth 
being 107 feet. Thus the deepest part of Loch Ard dips two feet below 
sea-level. The cubic mass of water contained in the loch is estimated at 
1,150,000,000 cubic feet, and the mean depth at nearly 44 feet, or 41 
per cent, of the maximum depth. The length of the loch is 113 times 
the maximum depth, and 277 times the mean depth. 
Loch Ard proper forms a comparatively simple basin, shoaling from^ 
the shores down to the deepest part. The 100-feet depression occupies 
a central position, and is about three-quarters of a mile in length. The 
75-feet depression is over miles in length, while the principal 50-feet 
depression, over 1| miles in length, is separated by a very short interval 
from a small detached area in the north-western part of the loch at 
Kinlochard, in which the depth exceeds 50 feet. The 25-feet contour- 
line is very irregular, and there are four isolated patches in which the 
depth exceeds 25 feet : the largest one in the southern prolongation at 
Couligartan has a maximum depth of 39 feet ; a second small area occurs 
between the southern prolongation and the island of Eilean Gorm, in 
which the maximum depth is 35 feet ; the other two areas are situated 
in the eastern prolongation of the loch, the maximum depth in the 
eastmost depression near the outlet of the loch being 33 feet, and in 
the other 39 feet. The soundings taken between Duke Murdoch’s 
castle and Briedach show that the bottom is very irregular : the first 
sounding gave a depth of 17 feet, followed by 44 feet, then 38 feet, then 
23 feet, then 31 feet, the bottom rising on approaching the elevation on 
which Briedach and a beacon are situated. 
The area of the bottom between the shore and the 25-feet contour- 
line is about 240 acres, or 40 per cent, of the area of the loch; that 
between the 25- and 50-feet contours is about 154 acres, or 25 per cent. ; 
that between the 50- and 75-feet contours is nearly 64 acres, or 11 per 
cent. ; that between the 75- and 100-feet contour-lines is about 78 acres, 
or 13 per cent. ; and that deeper than 100 feet is nearly 65 acres, or 
11 per cent. 
/ 
Lake of Menteitli (see Plate X.). — The Lake of Menteith resembles 
Loch Level! somewhat in outline, and in being relatively a very shallow 
basin. It is also historically related with Loch Leven, since Queen Mary 
at one time lived within their precincts ; the ruins of the Priory on 
Inchmahome, in which she resided before her removal to France, are of 
great architectural beauty and antiquarian interest. Its surface is only 
55 feet above the sea. Its maximum length is over \\ miles, and the 
maximum width over one mile, the mean width being five-eighths of a 
mile. Its waters cover an area of 652 acres (over one square mile), and 
it drains an area 6|^ times greater, or over 4000 acres (nearly 6| square 
miles). The number of soundings taken in the Lake of Menteith was 
375, the maximum depth being 77 feet. A small portion of the bottomi 
