174 
BATHYMETRICAL SURVEY OF 
into two deep basins by the shoaling of the bottom between the penin- 
sula of Hudha Dubh on the southern shore and the island opposite to it 
towards the northern shore, but even here there is a depth near the 
centre of 72 feet, so that the 25-feet and 50-feet areas are continuous 
from end to end of the loch. The 2 5 -feet contour-line follows approxi- 
mately the outline of the loch ; the 50-feet contour is extremely sinuous, 
in some places following the outline of the loch and in other places, 
especially in the central part of the loch, being far removed from the 
shore-line. Of the two 100-feet basins the south-eastern one is the 
larger and deeper, being over three-quarters of a mile in length, and 
widest towards the centre of the loch, narrowing on approaching the 
south-eastern prolongation. The maximum depth of the loch (180 feet) 
was observed towards the south-eastern end of this basin, and about 
200 yards from the north-eastern shore. The north-western 100-feet 
basin is less than half a mile in length, with a maximum depth of 
153 feet. Some of the lines of soundings show minor undulations of 
the lake-floor, and in one case towards the north-western end a sounding 
of 20 feet was recorded about 250 yards from the southern shore with 
a depth of 80 feet between it and the shore ; this shallow sounding may 
possibly be connected with the shallow water surrounding the large 
island lying to the south-west. There are indications of moderately 
steep slopes, especially along the south-western shore, where soundings 
exceeding 40 feet were recorded in various places close inshore. The 
areas between the consecutive contour-lines, and the percentages to 
the total area of the loch, are as follows : — 
0 to 
50 feet 
296 acres 
45 •! per cent. 
50 ,, 
100 „ 
239 ,, 
36-5 
100 ,, 
150 „ 
100 ,, 
15-3 
Over 
150 ,, 
21 ,, 
3T 
656 ,, 
100-0 
Bad 
a’ Ghaill 
was surveyed on 
September 18, 1902 
elevation of the lake-surface above the sea could not be determined. 
Temperature Observations. — Temperature observations taken at 
5 p.m. in the deepest part of the loch gave the following results: — 
Surface .. ... ... . . . ... 54°'5 Fahr. 
50 feet ... 54°-5 ,, 
100 ,, 50°-5 ,, 
170 „ 50° -0 „ 
This series shows a constant temperature down to 50 feet, then a fall of 
4° between 50 and 100 feet, the extreme range being 4°-5. 
Loch Otvskeich (see Plate XLI.). — Loch Owskeich (or Oiskaig) lies 
about a mile to the north-west of Loch Bad a’ Ghaill, to which it is 
