THE FRESH-WATER LOCHS OF SCOTLAND. 5 



The trend of the loch is almost north and south, the outline being some- 

 what oblong. The loch exceeds 1 J miles in length, with a maximum breadth 

 of over three-quarters of a mile, the mean breadth being over half a mile. 

 It is thus a very wide loch in relation to the length, the greatest width being 

 one-half, and the average width one-third, of the length. Its waters cover 

 an area of about 523 acres (over three-quarters of a square mile), and it 

 drains an area fourteen times greater, an area of 11^ square miles. Seventy 

 soundings were taken, the maximum depth of 26 feet being observed 

 towards the southern end and nearer the western shore. The volume of 

 water contained in the loch is estimated at 304 million cubic feet, and the 

 mean depth at 13^ feet, or one-half of the maximum depth. The loch was 

 surveyed on October 3, 1902, when the elevation of the lake-surface was 

 found to be 414-8 feet above the sea ; when levelled by the officers of the 

 Ordnance Survey on July 28, 1869, the elevation was nearly identical : 

 414*5 feet above sea-level. 



Loch an Ruathair is a comparatively shallow and flat-bottomed basin. 

 The 1 0-feet contour-line coincides" approximately with the outline of the 

 loch, but the area enclosed by the 20-feet contour is peculiar in form, 

 consisting of a main body situated in the southern portion of the loch, 

 sending out two prolongations in a northerly direction. These prolonga- 

 tions approach the eastern and western shores respectively, while the 

 central parts in the northern half of the loch are occupied by slightly 

 shallower water. The deepest sounding of 26 feet was taken in the centre 

 of the main body of deep water above referred to, about one-third of a 

 mile from the southern end of the loch. The slope of the bottom is 

 moderately steep off the western shore near the southern end, where 

 soundings of 10 and 12 feet were recorded about 100 feet off-shore, but 

 elsewhere the soundings indicate a very gentle slope. The flat-bottomed 

 character of the loch as a whole is shown by the following table, giving 

 the areas between the contour-lines, and the percentages to the total 

 area : 



Feet. Acres. Per cent. 



OtolO 169 ... 32 



10 20 251 ... 48 



over 20 '. 103 ... 20 



523 100 



A series of temperatures taken in the afternoon of October 3, 1902, 

 gave identical readings at the surface, at 10 feet, and at 18 feet, viz. 

 53-0 Fahr. 



Loch Coire nam Meann (see Plate II.). Loch Coire nam Meann (or 

 Coire nam Mang) lies about 4 miles to the north-west of Loch an 

 Ruathair, at the foot of Ben Griam Mhor. It is a good fishing loch, 

 the trout being very large, but is preserved. This loch is nearly circular 

 in outline, with a maximum diameter of over half a mile, covering an area 



