174 BATHYMETRICAL SURVEY OF 



into two deep basins by the shoaling of the bottom between the penin- 

 sula of Rudha 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 25-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 : 



to 50 feet 296 acres 45 '1 per cent. 



50,, 100 239 ,, 36-5 



100., 150 ,, 100 15-3 



Over 150 , 21 3'1 



656 100-0 



Loch Bad a' Ghaill was surveyed on September 18, 1902; the 

 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 r>4v> 



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 Owskeich (see Plate XLL). Loch Owskeich (or Oiskaig) lies 

 about a mile to the north-west of Loch Bad a' Ghaill, to which it is 



