84 BATHYMETRICAL SURVEY OF 



in length from north to south, and also in maximum breadth from east 

 to west, the mean breadth being over a quarter of a mile, or 45 per cent. 

 of the length. Its waters cover an area of over 100 acres, or about 

 one-sixth of a square mile, and it drains an area ten times greater 

 over 1J square miles. About 60 soundings were taken, the maximum 

 depth observed being 70 feet. The volume of water is estimated at 

 108,333,000 cubic feet, and the mean depth at nearly 25 feet, or 35 per 

 cent, of the maximum depth. The length of the loch is 44 times the 

 maximum depth and 126 times the mean depth. A ridge crosses the 

 loch at the narrowest part near the middle, the greatest depth on which 

 is 34 feet. On both sides of this ridge the water deepens, the maximum 

 depth in the southern basin being 45 feet, while the main deep basin 

 lies to the north of the ridge, the maximum depth of the loch (70 feet) 

 having been found less than a quarter of a mile from the north-eastern 

 angle of the loch, where there is a small 50-feet basin about one-tenth of 

 a mile in length; a short distance to the north-east is an isolated 

 sounding of 50 feet, comparatively close to the north-east shore, 

 separated from the 50-feet basin by a sounding of 38 feet. The 25-feet 

 basin is a continuous area half a mile in length and over a quarter of a 

 mile in breadth. The area of the lake-floor covered by less than 25 feet 

 of water is about 53 J acres; that covered by water between 25 and 50 

 feet in depth is about 44| acres; while that covered by more than 50 

 feet of water is about 2J acres. Loch Derculich was surveyed on May 

 27, 1903 ; the elevation above the sea could not be determined. 



Temperature Observations. A series of temperatures was taken 

 in the deepest part of the loch at 8 p.m. on May 27, 1903, with the 

 following results : 



The range of temperature from surface to bottom was 8'0, there being 

 a fall of 4-0 between the surface and a depth of 10 feet, and a further 

 fall of 3-3 between 10 and 25 feet. A comparison of these temperatures 

 with those taken in Lochs Daimh and Giorra on the previous day shows 

 that the water in Loch Derculich was much warmer from surface to 

 bottom than in the two lochs referred to : at the surface the temperature 

 was about 5, and at 10 feet 3 to 4 higher ; at the bottom it was 4 

 higher than at the bottom of Loch Daimh, and 1 higher than at the 

 bottom of Loch Giorra at a much less depth. 



. 



Loch Scoly (see Plate XXVI.). Loch Scoly, a small hill loch in 



