THE FRESH- AVATER LOCHS OF SCOTLAND. 
79 
Feet. 
Acres. 
Per cent. 
0 to 25 
57 
38*5 
25 „ 50 
39 
26-3 
50 „ 75 
33 
22-1 
75 „ 100 
12 
8*1 
Over 100 
8 
5*0 
149 
100-0 
The loch was surveyed on June 6, 1903, when the elevation was found 
to be 420*0 feet above the sea ; when visited by the Ordnance Survey 
officers on August 31, 1864, the elevation was 422*9 feet above sea-level. 
Temperature Observations . — Serial temperatures were taken in the 
deepest part of the loch with the following results : — 
Surface ... 
10 feet . . . 
20 „ ... 
45 „ ... 
90 ... 
60°-0 Fahr. 
59°'8 „ 
55°-7 „ 
47°*8 „ 
47°*0 „ 
These observations show a range of 13° from surface to bottom, there 
being a fall of about 4° between 10 and 20 feet, and a further fall of about 
8° between 20 and 45 feet. 
Loch Duhh-mor (see Plate XXXI.). — Loch Dubh-mor is a small but 
comparatively very deep loch situated less than a mile to the south-east 
of Loch Tralaig, and little more than a mile to the north-west of Loch 
Avich. The outline is sub^circular, though the shore-line is somewhat 
irregular, the maximum diameter being about one-third of a mile. The 
superficial area is about 30 acres, of which 64 per cent, is covered by less 
than 50 feet of water, and 9 per cent, by more than 100 feet of water. 
Near the north-eastern shore is a small deep area enclosing the maximum 
depth of 114 feet, the shore-slope being steepest in this locality. The 
volume of water is estimated at 66 million cubic feet, and the mean depth 
at 51 feet. The elevation could not be determiued by levelling, but is 
apparently about 900 feet above the sea. 
Temperature Observations . — Serial temperatures taken on June 5, 1903, 
in the deepest part of the loch gave the following results 
Surface .. 
10 feet 
16 M .. 
20 „ .. 
25 ,, .. 
50 „ .. 
100 „ .. 
67°*4 Fahr. 
57°*0 „ * 
54°-6 „ 
49°-2 „ 
47°-8 „ 
46°-0 „ 
44°-7 „ 
These readings are all lower than those taken at similar depths in 
the larger Loch Tralaig on the following day, the difference at the depth 
of 20 feet, for instance, being as much as 6°*5. The range shown by 
these observations is 12°*7, the most rapid fall being recorded between 
