THE FRESH-WATER LOCHS OF SCOTLAND. 
371 
0 to 100 feet 
415 acres 
27*0 per cent. 
100 „ 200 „ 
294 ,, 
19-1 „ 
200 „ 800 „ 
440 ,, 
28-6 
800 „ 400 „ 
256 „ 
16-6 
Over 400 ,, 
185 ,, 
8-7 
1540 ,, 
100-0 
The striking characteristic brought out by this table is the 
large area of the lake-floor covered by water between 200 and 300 
feet in depth — an area greater than in either of the two shallower 
zones. 
Temperature Observations . — At the early season when Loch Treig 
was surveyed, the surface was very little warmer than the bottom, the 
whole difference between the surface and 300 feet, on May 29, when the 
last series was taken being only l°-7 Fahr. Five days earlier. May 24, 
the difference was only 0°*7. In the interval the surface had risen 
in temperature l°-6, while at 300 feet the rise was only 0°’6. The three 
serials are contrasted in the table appended : — 
Depth in feet. 
May 24, 
11 '30 a.m. 
May 27, 
9 a.m. 
May 29. 
° Fahr. 
“ Fahr. 
° Fahr. 
Surface 
41-2 
41-6 
42-8 
5 
41-2 
10 
41-0 
41-2 
20 
41-0 
41-7 
30 
41 0 
40 
41-4 
50 
410 
420 
100 
40-9 
41-8 
150 
40-8 
200 
40-8 
41-2 
250 
40-6 
800 
40 5 
... 
4 T 1 
AnBuhli Lochan (see Plate LXXXIX.). — A very small loch situated 
about halfway between Loch Treig and the river Spean and a little to 
the west of the river Treig. It lies at an elevation of 785 to 790 feet 
above the sea, at the west side of an extensive deposit of gravel and 
sand, hills of moderate height rising- on the west shore (see Fig. 57). 
It is of somewhat oblong form, diversified by many little bays, and is 
shallow and weedy towards the south end. It is nearly a quarter of a 
mile long, and covers an area of about 84 acres. The greatest depth is 
40 feet, and the mean depth 15 J feet. The volume of water amounts 
to 6 millions of cubic feet. It has a drainage area of about one-sixth 
of a square mile, receiving only local superficial water. It drains by 
a small stream northward into the river Spean. 
