340 
BATHYMETRICAL SURVEY OF 
of water is about 178 acres, as compared with 270 acres covered by 
water between 50 and 100 feet in depth, or 35 per cent, as compared 
with 53 per cent. In most lakes the arrangement is the reverse of this, 
the areas between consecutive contour-lines drawn at equal intervals 
usually decreasing with increase of depth. The temperature of the 
surface water at the east end on commencing the survey was 50°‘0 
Fahr., while later in the afternoon, towards the opposite end the 
surface temperature was 49°-5 ; but an easterly gale having sprung 
up, it was found impossible to take serial temperatures beneath the 
surface. 
Loch na Beinne Bdine (see Plate LXXXII.). — Loch na Beinne 
Baine lies in Guisachan forest, about 4 miles to the south-east of Loch 
Beinn a’ Mheadhoin, and 8 or 9 miles to the west of Invermoriston on 
Loch Ness. It is irregular in outline, trends in a north-north-east and 
south-south-westerly direction, and is nearly a mile in length, with a 
maximum breadth of nearly half a mile. The superficial area is about 
154 acres, or a quarter of a square mile, and the area draining into it 
about IJ square miles. The maximum depth of 67 feet was observed 
about a quarter of a mile from the southern end of the loch, midway 
between an island of stones and the eastern shore. The volume of 
water is estimated at 190 million cubic feet, and the mean depth at 
28J feet. The loch was surveyed on June 6, 1904, but the elevation of 
the lake-surface above the sea could not be determined; the height of 
the water at the sluice was about 2 feet, and at one time the loch 
appears to have been considerably higher. 
Loch na Beinne Baine forms a simple basin; the 25-feet contour 
coincides approximately with the outline of the loch, but is deflected at 
the position of the island of stones off the western shore towards the 
southern end, while the 50-feet basin, based on soundings of 67, 64, 54, 
and 52 feet, is contained in the southern half of the loch, and is about 
a quarter of a mile in length. The soundings indicate in one or two 
places slight undulations of the lake-floor, but as a rule the slope of 
the bottom is regular and gentle. The area covered by less than 25 feet 
of water is about 95 acres, or 62 per cent, of the total area. 
T erri'perature Observations . — K series of temperatures taken in the 
deepest part of the loch gave the following results : — 
Surface ... ... ... ... ... ... ... 60° '8 Fahr. 
10 feet ... ... ... ... ... ... ... 60° '0 ,, 
20 „ 50° -5 „ 
40 „ 47°-6 „ 
60 ,, 46°-5 ,, 
These observations indicate an extreme range of temperature from 
suHace to bottom amounting to 14°*3, there being a fall of 9°*5 between 
