160 
BATHYMETRICAL SURVEY OF 
is estimated at 93 million cubic feet, and the mean depth at nearly 28 feet. 
The floor of the loch is somewhat irregular, there being three deep basins 
separated by two ridges. The largest and deepest basin occupies the 
central portion of the loch, while towards the northern end two soundings 
in 50 feet were taken, the greatest depth recorded on the intervening ridge 
being 34 feet ; near the southern end a depth of 36 feet was found, the 
deepest sounding on the ridge separating it from th« central deep basin 
being 21 feet. About 58 per cent, of the lake-floor is covered by less 
than 25 feet of water. 
The loch was surveyed on July 12, 1905, when the elevation was found 
to be 1585*0 feet above the sea ; the elevation given on the Ordnance Survey 
map is 1585*3 feet, but the date when levelled is not indicated. Tempera- 
tures taken in the deepest ])art of the loch showed a range from surface 
to bottom of 12° Fahr., the readings being as follows : — 
Surface ... 
25 feet ... 
50 „ ... 
85 „ ... 
61°-5 Fahr. 
56°-5 „ 
52°-4 „ 
49°-5 „ 
From the opposite table it will be seen that in the thirteen lochs under 
consideration, 663 soundings were taken, and that the aggregate area of 
the water-surface is over 2J square miles, so that the average number 
of soundings per square mile of surface is 252. The aggregate volume of 
water contained in the lochs is estimated at 2053 millions of cubic feet. 
The area drained by these lochs is 350.^ square miles, or about 133 
times the area of the lochs. 
