THE FRESH-WATER LOCHS OF SCOTLAND. 
195 
water is reduced to about half a mile. The outline is extremely irregular, 
and there are many islands large and small. The northern part of the 
loch is somewhat triangular, but its centre is filled by three large islands, 
the largest of w’hich, Eilean Leathann, is fully half a mile long. 
As in Loch Scadavay, there are many distinct depressions, separated 
by shallows. In each of these there is considerable depth. In the 
narrow part, west of Eaval, there are three basins with maxima of 
51, 57, and 50 feet respectively. South of Eilean Leathann is a basin 
with a de^ith of 65 feet, and east of the same island one of 58 feet. North 
of Eilean Leathann is a depth of 48 feet. Between Eilean Mor and the 
stream flowing out to the north into Loch Eport lies the deepest basin 
in the loch. It is of very limited extent, measuring only about a quarter 
of a mile each way, betw'een the islands and the shore, but has the 
remarkable maximum depth of 151 feet. To the west of this is another 
very small triangular area, having a depth of 70 feet. The mean depth 
of 25| feet is less than that of Loch a’ Ghlinne-Dorcha, and a little more 
than that of Loch Crogavat. The greater part of the shore is of rock, 
forming on the west a range of cliffs, with some small stretches of gravel, 
stones, and peat. Immediately under the north slope of Eaval is the 
largest stretch of peat-covered gravel, extending about a mile without 
any exposed rock. The large islands, and most of the small ones, are 
of rock. On Eilean Leathann mounds of stony debris lie over the rock. 
The level was ascertained on June 15, 1904, by measuring from Loch na 
Ceithir-Eileana to be 8*2 feet above the sea. 
Loch Obisary is tidal. Though the surface level is little affected by 
the tides, these enter often enough to render the water quite salt, and to 
permit numerous marine animals to- live in it. Mussels (marine) were 
found adhering to the fresh-water weeds, and marine Crustacea abounded 
among the weeds. Large beds of a slender grass-like plant, which 
appeared to be Juncus sujjinus, but was not in flower, reached the surface 
from depths of from 14 to 18 feet. F’rom the deepest part a black gritty 
mud was obtained. 
A series of temperatures was taken in the deep hole at noon, June 25, 
1904. There was a range of 8°*o, and a remarkable inversion was indicated, 
the thermometer at 50 feet reading 1° lower than at the bottom. The 
readings at 50 feet and 100 feet were repeated, after testing by again 
reading the surface temperature, and were consistent with the first 
readings : — 
Surface (repeated) 55°-5 Fahr. 
10 feet 55°-5 „ 
25 „ 50°-4 ,, 
50 ,, (repeated) 47°'2 ,, 
100 ,, (repeated) 48°-2 ,, 
150 „ 48°-2 ,, 
Loch cd Chladaich (see Plate LXXV.). — A very small narrow loch on 
