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 1^ 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 Menteith (see Plate X.). The Lake of Menteith resembles 

 Loch Leven 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 1J 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-J times greater, or over 4000 acres (nearly 6J 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 bottom 



