THE FRESH- WATER LOCHS OF SCOTLAND. 
167 
loch, especially in the one to the south of Creag a’ Choire Mhoir, the 
current was so strong that the greatest difficulty was experienced in 
rowing the boat against it, though assisted by a strong north-west wind. 
The loch is nearly miles in length, with a maximum breadth of over 
one-third of a mile (or about 600 yards), the mean breadth being about 
one-seventh of a mile (or about 250 yards). Its waters cover an area 
of about 209 acres (or nearly one-third of a square mile), and it drains 
directly an area of about 6^ square miles, but since it receives the 
outflow from Loch Veyatie and the other lochs in the basin, its total 
drainage area is nearly 53 square miles — an area 160 times greater 
than that of the loch. Over 100 soundings were taken, the maximum 
depth observed being 90 feet. The volume of water is estimated at 
185,510,000 cubic feet, and the mean depth at 20J feet. Fionn Loch 
is very irregular in outline, broads and narrows alternating with each 
other, and the contours of the bottom are correspondingly diversified. 
There is a long 'narrow tortuous area exceeding 25 feet in depth, 
extending from near the north-west end of the loch to north of the 
reedy bay where the stream from Na Tri Lochan enters, and about 
1| miles in length; a short distance to the south-east is a second small 
25-feet area, with a maximum depth of 37 feet. The deepest water 
occurs in the wide part of the loch about half a mile to the south-east 
of the exit of the Kirkaig river, where there is a small area exceeding 
75 feet in depth, the maximum depth of 90 feet having been observed 
about 120 yards from the south-western shore. The areas between 
the consecutive contour-lines, and the percentages to the total area of 
the loch, are as follows: — 
0 to 25 feet 
153 acres 
73 *0 per cent. 
25„ 50 „ 
49 „ 
23-5 „ 
50 ,, 75 ,, 
2 ,, 
1-0 
Over 75 ,, 
o ,, 
2-5 „ 
209 ,, 
100-0 
This table shows how circumscribed the deep-water area is, 97 per cent, 
of the lake-floor being covered by less than 50 feet of water. The Fionn 
Loch was surveyed on September 16, 1902. The elevation of the lake- 
surface was determined, by levelling from bench-mark, as being 356‘9 
feet above the sea ; when levelled by the officers of the Ordnance Survey 
on October 21, 1870, the elevation was found to be 357*1 feet above 
sea-level. The temperature of the surface water on September 16, 1902, 
was 53°*0. 
