THE FRESH-WATER LOCHS OF SCOTLAND. 227 



on soundings of 51 and 53 feet, lies in the centre of the south-western 

 part of the loch. The 75-feet area is situated in the north-western part 

 of the loch, and sinks below sea-level, the deepest spot being 25 feet 

 below the level of the sea. 



The areas between the consecutive contour-lines, and the percentages 

 to the total area of the loch, are as follows : 



to 25 feet 72 acres 35 '8 per cent. 



25,, 50 69 34-4 



50,, 75 39 19-8 



Over 75 , 20 . lO'O 



200 , 100-0 



Thus 70 per cent, of the lake-floor is covered by less than 50 feet of 

 water. 



Temperature Observations. A series of temperatures was taken in 

 the deep part of the loch at 2.30 p.m. on July 25, 1902, with the 

 following results : 



Surface 57'0 Fahr. 



10 feet 57-0 



25 56-8 



50 53'0 



80 ,, 50-2 



This series shows an almost constant temperature down to 25 feet, 

 then a rapid fall of 3'8 between 25 and 50 feet, and a further fall of 

 2-8 between 50 and 80 feet. 



Loch Gliiuragarstidh (see Plate XLVII.). Loch Ghiuragarstidh 

 lies about half a mile to the north of Loch Kernsary, into which it 

 drains by the Allt Loch Ghiuragarstidh. The islands are covered by a 

 few feet of peat and soil, and have many fir trees growing on them. 

 The loch was surveyed on July 28, 1902; the elevation of the lake- 

 surface was determined, by levelling from Loch Kernsary, as being 

 11 6' 7 feet above mean sea-level. 



Loch Ghiuragarstidh is about 1200 yards in length, with a maximum 

 breadth of about 370 yards, the mean breadth being about 230 yards. 

 Its waters cover an area of 58 acres, and it drains an area nearly ten 

 times greater, or about 560 acres. The volume of water is estimated 

 at 23 million cubic feet, and the mean depth at 9 feet. The breadth of 

 the loch at the position of the deepest sounding is 27 times the depth. 

 The shore development is 1-63, and the insulosity 0'028. The bottom is 

 very irregular in the southern half of the loch, large boulders and reefs 

 rising above the surface of the water in many places. In the northern 

 half the lake-floor is more regular, and it is only in this part that the 

 depth exceeds 10 feet, the maximum depth of 37 feet having been 



