THE FRESH-WATER LOCHS OF SCOTLAND. 
213 
Loch Baoinavat (see Plate LXXXIV.) is a small loch about 3 miles 
north-east of Carloway, on the west coast, on a land surface gently rising 
towards the south. It is three-quarters of a mile long, from east to west, 
and a quarter of a mile broad at the extreme west end. It is narrow at 
the east end, and expands and deepens westward. A very small area, 
exceeding 50 feet in de[>th, with the maximum of 61 feet, lies close to the 
north shore and near the west end ; the mean depth is 20J feet, the area 
about 73 acres, and the volume 65 millions of cubic feet. The drainage 
area is barely half a square mile. The outflow is by a small stream, which, 
leaving the east end of the loch, flows north past several mills, into Loch 
na Aluilne. The surface was 109*5 feet above sea-level on August 22, 
1903. The temperature only varied one-fifth of a degree from surface to 
bottom — surface, 55°*8 Fahr. ; 54 feet, 55°*6. 
Loch Langavat (see Plate LXXXV.). — Loch Langavat, the most 
extensive body of fresh water in the island of Lewis, is centrally situated 
in the broadest part of the island, between Lochs Seaforth and Erisort on 
the east, and Lochs Resort and Little Roag on the west. The upper end 
of the loch lies among hills of over 1500 feet in height. The land falls 
towards the lower end, which borders on a broad plain, studded with 
innumerable lochs, stretching for miles to the north and east. In form it 
is very irregular — long and narrow, with undulating shore-line and zigzag 
axis — several constrictions and bends dividing it into distinct basins. The 
length, in a straight line from south-west to north-east, is 1\ miles ; if the 
centre line were followed it would be much greater. The maximum 
breadth is three-quarters of a mile. There are three large basins of over 
25 feet in depth, besides some smaller depressions. The largest and 
deepest basin occupies the southern section of the loch, which is 3J miles 
long, fully half a mile broad in the centre, and is almost straight. The 
25-feet contour is parallel with the shore-line, and encloses an area nearly 
3 miles long. The area enclosed by the 50-feet contour is fully a mile in 
length, and contains two small areas over 75 feet in depth, with maxima 
of 97 and 98 feet respectively, separated by an elevation on which the 
depth is 72 feet. This large basin is separated from the next by a very 
narrow strait where the depth is only 9 feet. The mid basin is deepest 
at the south-western end, where the depth of 90 feet occurs, and shallows 
and contracts towards the north-east. The next bend to the east leads to 
the third section of the loch, which is as long and broad as the first 
(3^ miles long and three-quarters of a mile broad), but of much m#re com- 
plex form, the axis curving, the shore-line much broken up, the contours 
irregular and interrupted by numerous islands. The largest area of over 
25 feet is at the south-west end, and has a maximum depth of 40 feet ; 
smaller areas of greater depth are found further to the north-east. In the 
last large expansion near the lower end of the loch is a depth of 65 feet. 
The mean depth is 25 feet, the superficial area 3^ square miles, and the 
