THE FRESH- WATER LOCHS OF SCOTLAND. 



79 



depth of 119 feet having been observed towards the eastern end of the 

 basin. The eastern basin just falls short of attaining a depth of 100 

 feet, the maximum observed being 99 feet; the 75-feet contour is 

 approximately oblong in outline and nearly one-third of a mile in 

 length. The 50-feet basin is a continuous area stretching from about a 

 quarter of a mile from the west end to within 100 yards from the east 

 end of the loch, and is nearly two and a half miles in length. 



The area of the lake-floor covered by less than 50 feet of water is 

 about 352 acres, or 56 per cent, of the entire area of the loch; the area 

 covered by water between 50 and 100 feet in depth is about 217 acres, 



FIG. 23. LOCH TUMMEL. 



(Photograph by J. Parsons, B.Sc.) 



or 34^ per cent. ; and that covered by more than 100 feet of water is 

 about 60 acres, or 9J per cent, of the total area of the loch. 



Loch Tummel was surveyed 011 April 23 and 24, 1902, the level of 

 the surface of the water being found, by levelling from Ordnance Survey 

 bench-mark, to be 454-5 feet above the sea. When levelled by the 

 surveyors of the Ordnance Survey on June 26, 1860, the surface of the 

 water was found to be 453'3 feet above sea-level. 



Temperature Observations. The temperature of the surface water of 

 Loch Tummel at 1.30 p.m. on April 23, 1902, was 43'2 Fahr. ; at 

 9.45 a.m. on the next day (April 24) the surface temperature was 45'0, 

 and at 1 p.m. in the centre of the loch the surface temperature was 





