THE FRESH- WATER LOCHS OF SCOTLAND. 275 



basin opposite the entrance of the Allt Bhreacnais, hased on half a dozen 

 soundings, the deepest in 58 feet. Silting up has taken place at the 

 embouchures of the inflowing streams, notably at the two ends of the loch ; 

 to this is evidently due the curious loop in the 25-feet contour at the 

 western end. In the south-western angle of the loch, where the Allt 

 Grain enters, lies a little basin with a maximum depth of 24 feet, cut off 

 from the main loch by the narrows between Eilean Mhic na h-Ainnis and 

 the western shore, in which the depth is only a foot. The areas between 

 the contour-lines, and the percentages to the total area, are as follows : 



Feet Acres. Per cent. 



to 25 263 ... 37-4 



25 50 ... 214 ... 30-5 



50 75 148 ... 21-1 



Over 75 78 ... ll'O 



703 100-0 



A series of temperatures taken in the deepest part of the loch at 

 6-10 p.m. indicated a uniform temperature of 41'0 Fahr. from surface to 

 bottom. Two surface readings near shore earlier in the day gave 43 " - 9 

 and 44 -1. 



Lochan na B\ (see Plate CXXVI.) lies in Argyllshire near the boun- 

 dary of Perthshire, 10 miles from Dalmally and a mile from Tyndrum, the 

 road and railway between these places passing along the northern shore. 

 It is a shallow loch, trending almost east and west, surrounded by swampy 

 ground covered in places with small trees. It is about three-quarters of a 

 mile in length, with a maximum breadth of about one-eighth of a mile, and 

 covers an area of about 39 acres. The maximum depth of 6 feet was 

 observed near the centre of the loch. The volume of water is estimated at 

 6 million cubic feet, and the mean depth at over 3 feet. The loch was 

 surveyed on May 21, 1903, when the elevation was 823'25 feet above sea- 

 level ; the elevation is given on the Ordnance Survey map as 822 feet, but 

 the date is not mentioned. 



Loclt EdrrJinc (see Plate CXXII.) is situated near the head of Loch 

 Awe, and is irregular in outline, trending almost north and south. The 

 loch is nearly two-thirds of a mile in length, with a maximum breadth of 

 over one-third of a mile, covering an area of about 70 acres, and draining 

 an area of over 12 square miles. The basin is simple, though the contour- 

 lines are sinuous in character, the maximum depth of 58 feet being 

 observed towards the south end. The volume is estimated at 70 million 

 cubic feet, and the mean depth at 23 feet. 



It was surveyed on May 22, 1903, when the elevation was found to be 

 r_'2'4 feet above sea-level; on June 25, 1864, the Ordnance Survey officers 

 determined the elevation as 122'0 feet. The temperature of the surface 

 water was 51'<> Fahr. 



