116 
BATHYMETRICAL SURVEY OF 
at other places the shores are less steep, and surrounded by smooth, 
rounded, heather-covered hills. The water was very dark in colour, 
and, though there was apparently no great amount of inflow, there was 
a considerable outflow. Loch Fender is one-third of a mile in length 
from north-east to south-west, and one-fifth of a mile in maximum 
breadth, the mean breadth being over one-tenth of a mile, or 32 per 
cent, of the length. Its waters cover an area of over 22 acres, and it 
drains an area nine times greater — an area of over one-third of a square 
mile. Nearly 60 soundings were taken, the maximum depth observed 
being 78 feet. The volume of water contained in the loch is estimated 
at 30,998,000 cubic feet, and the mean depth at 31| feet, or 41 per 
cent, of the maximum depth. The length of the loch is 22 times the 
maximum depth and 55 times the mean depth. Loch Fender forms a 
simple basin, the bottom sloping down on all sides to the deepest part, 
which is approximately centrally placed, but nearer the north-east than 
the south-west end, the maximum depth of 78 feet having been observed 
about 300 feet from the north-eastern shore. The average slope of the 
bottom is very steep, especially off the south-eastern shore, where were 
recorded soundings of 29 feet 20 feet from shore, 26 feet 30 feet from 
shore, and 17 feet 20 feet from shore, giving gradients of 1 in 0'7 and 
1 in L2. Off the north-western shore the gradient is gentler, and the 
north-west angle, where the burn flows into the loch, is comparatively 
shallow and obstructed by weeds. The area of the lake-floor covered 
by less than 25 feet of water is about 11 acres, or 51 per cent, of the 
total area of the loch ; that covered by water between 25 and 50 feet in 
depth is about 5 acres, or 21 per cent. ; and that covered by more than 
50 feet of water is about 6 acres, or 28 per cent, of the entire area of 
the loch. Loch Fender was surveyed on June 5, 1903, and, from spot- 
levels near the loch, it was estimated that the elevation of its surface 
was approximately 1888 feet above sea-level. 
T em'perature Observations . — Temperatures taken in the deepest part 
of the loch at 1 p.m. gave the following results: — 
Surface . 
5 feet , 
10 „ . 
15 ,, . 
25 „ 
50 ,, 
75 „ . 
58° -0 Fahr. 
57° -8 ,, 
52° '0 , , 
45° 0 ,, 
44° 0 „ 
48° -0 ,, 
42° -4 ,, 
This series shows a range of temperature from surface to bottom 
amounting to 15°*6, there being a fall of 12°‘8 between 5 and 15 feet 
{i.e. 5°-8 between 5 and 10 feet, and 7°*0 between 10 and 15 feet). The 
decrease of temperature in the layer of water between 10 and 15 feet is 
thus equal to 1°*4 per foot, whereas the fall is only 1° in the underlying 
layer between 15 and 25 feet. 
