THE FRESH-WATER LOCHS OP SCOTLAND. 83 



about 65 per cent, is covered by less than 25 feet of water. The con- 

 formation is simple, two soundings at the maximum depth of 45 feet 

 being recorded near the middle of the loch. The loch was surveyed on the 

 same day as the upper loch, the elevation being approximately 336 feet 

 above the sea. The surface temperature was 56'8 Fahr. 



From the opposite table it will be seen that in the thirteen lochs under 

 consideration 855 soundings were taken, and that the aggregate area of the 

 water-surface is 1*60 square miles, so that the average number of soundings 

 per square mile of surface is 515. The aggregate volume of water con- 

 tained in the lochs is estimated at 1828 millions of cubic feet. The 

 area drained by these lochs is about 34 square miles, or 20 J times the area 

 of the lochs. 



