176 
BATHYMETRICAL SURVEY OF 
The details regarding the lochs in the Inver, Roe, Kirkaig, Polly, 
and Garvie basins are collected together in the following table for 
convenience of reference and comparison. Where the elevation above 
the sea was not determined by levelling from bench-mark, the 
approximate elevation is given in brackets ; in the case of Lochs 
Urigill, Cam, Lurgain, and Owskeich, the Ordnance Survey level is 
given with an indication of the date when levelled. 
From this table it will be seen that in the twenty lochs under 
consideration, 2540 soundings were taken, and that the aggregate area 
of the water-surface is over 12 J square miles, so that the average 
number of soundings per square mile of surface is 200. The aggregate 
volume of water contained in the lochs is estimated at about 20,355 
millions of cubic feet. The area drained by these lochs is about 150^ 
square miles, or twelve times the area of the lochs. 
