368 BATHYMETRICAL SURVEY OF 



feet ; this is nearly identical with the level determined by the Ordnance 

 Survey officers on May 27, 1870, viz. 1268-6 feet. 



The bottom of Loch Ossian is very uneven, the transverse, as well 

 as longitudinal, sections being undulate. Only the 25-feet contour 

 follows the line of the shore. The 50-feet contour encloses an area 

 2 miles in length. The south-western portion of this for three-quarters 

 of a mile is exceedingly narrow. Near the middle of the loch it 

 broadens to a quarter of a mile, and continues broad to near the out- 

 flow. The area over 75 feet in depth is fully a mile in length, that 

 over 100 feet half a mile, and that over 125 feet a quarter of a mile in 

 length. One mile from the upper end there is in the centre of the loch 

 a shoal, over which the depth is only 11 feet. The approximate areas 

 between the contour-lines, and the percentages to the total area of the 

 loch, are as follows : 



to 25 feet 214 acres 32 '6 per cent. 



25 50 234 35-6 



50,, 75 104 15-8 



75 100 72 10-9 



Over 100 ,, 33 ,, 5'] 



657 . 100-0 



It will be observed that the area of the lake-floor covered by water 

 between 25 and 50 feet in depth is larger than the shore-zone covered 

 by less than 25 feet of water. 



Temperature Observations. The following temperatures taken at 

 1 p.m. on May 16, 1902, show a range of less than 1 Fahr. : 



Surface 44 '3 Fahr. 



10 feet ... 44-l ,, 



25 ' 43-7 



50 43'8 ,, 



100 ,, 43'4 



Loch Gliuilbinn (see Plate LXXXVIL). Loch Ghuilbinn (or 

 Gulbin) is a small and relatively broad loch, lying in the midst of the 

 high mountainous region between Lochs Ericht, Treig, and Laggan. 

 The long axis runs nearly north and south. The surrounding hills rise 

 on all sides into peaks of well over 3000 feet. The loch is fully three- 

 quarters of a mile long, and nearly half a mile in greatest breadth, 

 with a mean breadth of a little over a quarter of a mile. The greatest 

 depth is 49 feet, and the mean depth over 13 feet. The superficial area 

 is about 146 acres, or nearly a quarter of a square mile, and the volume 

 85 million cubic feet. It receives the drainage of a basin extending to 

 29 square miles, including Loch Ossian. It is fed chiefly by the river 

 Ossian, which, besides bringing the overflow of Loch Ossian, receives 



