THE FRESH-WATER LOCHS OF SCOTLAND. 
229 
These figures indicate that the average slope is gentle in the 
shallower water, and much steeper in depths exceeding 50 feet, but 
it will be observed from the map that the contour-lines approach 
very close to the shores in certain places, indicating a steep slope in 
these positions. 
Temperature Observations . — The surface temperature at 11.45 a.m. 
on July 29, 1902, was 56°-l, and at 4 p.m. on July 30, when the 
following series was taken, it was more than half a degree lower : — 
Surface 
10 feet 
20 „ 
30 „ 
50 ,, 
, 75 „ 
85 
120 „ 
55° -4 Fahr. 
55° -4 „ 
55° -4 „ 
55° -4 „ 
53° -6 „ 
49°-8 ,, 
48° -4 „ 
47° -2 „ 
This series shows a constant temperature from the surface down to 
30 feet, then a slight fall of 1°'8 between 30 and 50 feet, followed by a 
rapid fall of 5°-2 between 50 and 85 feet, thence to the bottom a slight 
fall of l°-2, the total range of temperature from surface to bottom 
being 8°-2. 
Loch Mhic’ Ille Riahhaich (see Plate L.). — Loch Mhic’ Hie Hiabhaich 
is a small, irregular, shallow loch lying to the south-east of Loch a’ 
Bhaid-Luachraich (into which it flows by the Allt na Criche), surrounded 
by low, rounded hills ; on one of the islands is a fortress, but nothing 
seems to be known of its history. It was surveyed on July 31, 1902, 
but its elevation above the sea could not be determined; from the 
contour-lines on the Ordnance Survey maps it is apparently rather 
less than 600 feet above the sea. It is half a mile in length from 
north to south, and rather less in maximum breadth from south-east to 
north-west. It covers an area of about 36 acres, and drains an area of 
nearly three-quarters of a square mile. Two soundings of 12 feet were 
taken near the north end at the outflow, and a sounding of 10 feet off 
the eastern shore of the larger island ; with these exceptions, the lake- 
floor is covered by less than 10 feet of water. The volume is estimated 
at 8 million cubic feet, and the mean depth at 5J feet. 
The temperature of the surface water at 12.30 p.m. on July 31, 
1902, was 57°-0 Fahr. 
Loch nan Dailthean (or na Daline), lying to the south-west of Loch 
Mhic’ Ille Hiabhaich, and flowing into Loch Thuirnaig (an inlet of 
Loch Ewe), was visited by the Lake Survey, but not sounded. It is 
said to be so shallow that cows may walk over the whole of it, except 
a small hole near Thuirnaig House, in which the depth is 4 feet. 
