366 
BATHYMETRICAL SURVEY OF 
portions ; the largest of these approaches the west end of the loch, and 
is miles in length. Two lesser areas, each about two-thirds of a mile 
in length, occur close together in the narrow middle part of the loch. 
The 75-feet area towards the upper end of the loch is nearly miles in 
length. The shallowings between these various basins are all opposite 
the mouths of streams, but in one instance the stream is too small to 
account for the shallowing, and other larger streams appear to have had 
no effect on the contours. The largest 7 5 -feet basin includes two areas 
of over 100 feet, a very limited one in the narrow part of the loch, with 
a maximum depth of 105 feet, and another, 1 J miles in length, near the 
west end. This 100-feet area is at the broadest and deepest part of the 
lake, and includes an area, two-thirds of a mile in length, of over 150 
feet, in which two soundings of 174 feet and 170 feet respectively were 
taken, with a shallowing of 155 feet between them. The two small 
75 -feet areas near the middle of the lake include depths of 112 and 114 
feet respectively. The easternmost 7 5 -feet area includes two very small 
basins of over 125 feet, with maxima of 133 and 141 feet. Many lesser 
irregularities occur. For about half a mile from the inflow of the 
river Pattack the loch is very shallow, and the bottom and shores 
are sandy. 
The approximate areas between the contour-lines at intervals of 
50 feet, with the percentages to the total area of the loch, are given 
in the following table : — 
0 to 50 feet 
765 acres 
40 ‘3 per cent. 
50 ,, 100 ,, 
686 ,, 
36*1 ,, , 
100 ,, 150 ,, 
396 ,, 
20-8 
Over 150 ,, 
53 , , 
2-8 
1900 „ 
100-0 
— — 
' 
Temperature Observations. 
— The following 
series of temperatures. 
taken towards the east end 
of the loch at 
noon on June 3, 1902, 
indicates a range of only l°-2 Fahr., the greater part of the variation 
occurring in the upper 10 feet of water; — 
Surface 
5 feet 
10 ,, 
20 
30 ,, 
50 ,, 
70 „ 
100 „ 
47° *0 Fahr. 
46° -6 „ 
46° -2 „ 
46° -0 „ 
45° -9 ,, 
45° -9 ,, 
45° -8 ,, 
45° -8 „ 
Loch Ossian (see Plate LXXXVI.). — Loch Ossian (or Ouchan) is 
a narrow loch in a valley running nearly north-east and south-west to 
the north of Hannoch moor (see Fig. 55). It lies at a considerable 
