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 the 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 part of the lech showed a range from surface 

 to bottom of 12 Fahr., the readings being as follows : 



Surface 61-5 Fahr. 



25 feet 56-5 



50 52-4 



85 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 350J square miles, or about 133 

 times the area of the lochs, 



