THE FRESH- WATER LOCHS OF SCOTLAND. 7 



which is, according to the Ordnance Survey maps, 270 feet above sea- 

 level, has a total length of about 4 miles, with a maximum width of less 

 than three-quarters of a mile. The mean breadth is about two-fifths 

 of a mile, or 704 yards, being 10 per cent, of the length. Its waters 

 cover an area of about 1030 acres (or over 1| square miles), and it drains 

 an area nearly eighteen times greater, or about 18,300 acres (28J square 

 miles). The total number of soundings taken in Loch Vennachar was 

 423, an average of 263 per square mile, the average depth of these being 

 41 feet, and the greatest depth observed being 111 feet (18 \ fathoms), 

 so that it may be regarded as a relatively shallow loch. The bulk of 

 water contained in the loch is estimated at 1,903,000,000 cubic feet, 

 and the mean depth at 42J feet (7 fathoms), being 38 per cent, of the 

 maximum depth. The length of the loch is 190 times the maximum 

 depth, and 498 times the mean depth. 



FIG. 6. LOCH VENNACHAR, LOOKING SOUTH-WEST. 



(Photograph hi/ G. W. Wilton.) 



It will be observed from an examination of the map that the loch is 

 deeper in the eastern than in the western portion, the western end being 

 shallow and covered with weeds, so that one must proceed nearly a mile 

 from the west end of the loch before encountering depths of 50 feet, 

 and this is merely a small patch separated from the principal 50-feet 

 depression by a distance of nearly two-thirds of a mile. In August the 

 water in the loch is at its lowest, and the weeds at the west end most 

 abundant. The principal 50-feet depression is about 2 miles in length, 

 with a mean breadth of about one-third of a mile and a maximum 

 breadth of nearly half a mile. It includes two 100-feet depressions : the 

 first one is very irregular in shape, situated approximately in the centre 

 of the loch, and contains the greatest observed length (111 feet), which 

 lies towards the northern shore; the second one occupies the central 

 portion of the large 50-feet depression, the greatest depth observed 



