THE FBESH-WATER LOCHS OF SCOTLAND. 31 
mile from the head of Scourie hay, but at an elevation of nearly 50 feet 
above the sea. The loch trends almost east and west, and is nearly a mile 
in length, with a maximum breadth of a third of a mile, its waters covering 
an area of about 111 acres, or one-sixth of a square mile. The maximum 
depth of 121 feet was observed approximately near the middle of the loch, 
but rather nearer the west than the east end. The volume of water is 
estimated at 270 million cubic feet, and the mean depth at 55 J feet. The 
loch was surveyed on September 8, 1902, when the elevation of the lake- 
surface was found to be 48*5 feet above the sea, so that the 50-feet contour- 
line on the map shows approximately the area of the bottom which falls 
below the sea-level. 
Loch a’ Bhaid Daraich forms a simple flat-bottomed basin, with no 
indication of any pronounced iiTegularity. The contour-lines coincide 
approximately with the outline of the loch, having here and there a 
slightly sinuous character, and there are in places steej) off-shore slopes, 
as, for instance,v off the northern shore towards the west end, where a 
sounding in 45 feet was taken about 40 feet from shore — a gradient ex- 
ceeding 1 in 1. The following table gives the approximate areas between 
the consecutive contour-lines drawn in at equal intervals of 25 feet, and 
the percentages to the total area of the loch : — 
Feet. 
Acres. 
Per cent. 
Oto 25 
26 
23-3 
25 „ 50 
29 
26-2 
50 „ ^75 
19 
17-6 
75 „ 100 
. . • 
22 
19-5 
Over 100 
15 
13-4 
111 
100-0 
These figures show that Loch a’ Bhaid Daraich departs from the usual 
rule of decreasing area with increasing depth, for in each of the zones 
between 25 and 50 feet, and again between 75 and 100 feet, the area is 
greater than in shallower water. 
Temperature Observations . — A series of temperatures taken at 2 p.m. on 
the date of the survey, in the deepest part of the loch, gave the following 
results : — 
Surface ... 
20 feet 
40 „ 
42-5 „ 
45 „ 
50 „ 
60 „ 
100 „ 
no „ 
57°-2 Fahr. 
57°*1 „ 
56°-l „ 
54°-8 „ 
52'^-0 „ 
50°-8 „ 
50°-0 „ 
48°-9 „ 
These observations show a range of temperature throughout the body 
of water amounting to 8°*6, the greatest fall being observed between 42J 
and 45 feet, viz. a fall of 2°*8 in the interval of 2J feet of depth— -a decrease 
exceeding 1° per foot. 
