274 
BATHYMETRICAL SURVEY OF 
narrowing towards the eastern end. It is over 1| miles in length, with 
a maximum breadth of one-third of a mile, the mean breadth being a 
quarter of a mile. Its waters cover an area of 267 acres, or nearly half 
a square mile, and it drains an area 72 times greater — an area exceed- 
ing 30 square miles. The maximum depth of 176 feet was observed 
approximately near the centre of the loch. The volume of water is 
estimated at 819 million cubic feet, and the mean depth at 70 J feet. 
The loch was surveyed on August 22, 1902, when the elevation of the 
lake-surface was found to be 465'6 feet above sea-level ; when visited 
by the officers of the Ordnance Survey on June 6, 1870, the elevation 
was 465T feet above the sea. 
Loch Beannachan forms a simple basin, the contour-lines following 
approximately the outline of the loch, but approaching in each case 
nearer to the western than to the eastern end. There is a large wooded 
island at the entrance of the inflowing river at the west end, and a 
small island near the exit of the outflowing river at the opposite end. 
The slope offshore is in some places very steep, especially at certain 
points along the southern shore, and at the position of the deepest 
sounding the slope is steeper oft the southern than off the northern 
shore, as is shown in the cross section C-D on the map. The longi- 
tudinal section A-B shows the gradual slope towards the two ends, 
with quite a flat-bottomed character in the deeper water, which is also 
indicated by the larger area between 100 and 150 feet than between 
50 and 100 feet, as given in the following table; — ■ 
0 to 
50 feet 
1 13 acres 
42 '3 per cent. 
50 „ 
100 „ 
67 „ 
25-0 
100 „ 
150 „ 
72 „ 
27-2 
Over 
150 ,, 
15 ,, 
5 "5 , , 
267 „ 
lOOO 
Temperature Observations . — A series of temperatures taken in the 
deepest part of the loch at 4.15 p.m. on August 22, 1902, gave the 
following results : — 
Surface 
10 feet 
20 „ 
30 „ 
40 „ 
50 „ 
60 „ 
75 „ 
100 „ 
170 „ 
55° 0 Fahr. 
55° -0 
? J 
54° -8 
5 1 
53° -0 
3 3 
52° -9 
5 3 
52° -0 
3 5 
50° ’5 
3 3 
46° -9 
3r 
46° T 
3 3 
46° -0 
3 3 
