54 BATHYMETRICAL SURVEY OF 



Feet. Acres. Per cent. 



Oto25 74 ... 54 



25 50 45 ... 33 



Over 50 18 ... 13 



137 100 



Temperature Observations. The following series of temperatures taken 

 in the deepest part of the loch at 5 p.m. on the date of the survey 

 shows (as in the case of Dubh Loch) a uniform temperature in the upper 

 layers of water, with a maximum fall beyond the depth of 50 feet : 



Surface 55-3 Fahr. 



5 feet 55-3 



10 55-3 



20 ' 55-3 



30 54-9 



50 54-0 



60 51-8 



Here the total range is only 3 C< 5, and the fall of temperature between 

 50 and 60 feet 2*2 ; while in Dubh Loch the range was larger, the surface 

 temperature being higher and the bottom temperature lower, and the fall 

 of temperature greater, than in Loch Bad an Sgalaig. 



Loch a 1 Bhealaich (see Plate XIX.). Loch a' Bhealaich (or Vallich) lies 

 less than a mile to the south-west of Loch na h-Oidche, and is almost 

 continuous with Loch a' Ghobhainn, the stream flowing from Loch a' 

 Bhealaich into Loch a' Ghobhainn being only about 200 yards in 

 length, Loch a' Bhealaich trends in a west-north-west and east-south- 

 east direction, and is If miles in length, varying considerably in width, 

 the maximum width being less than half a mile, while the mean breadth of 

 the entire loch is a quarter of a mile. Its waters cover an area of about 

 279 acres, or nearly half a square mile, and it receives the drainage 

 from an area of 5 square miles. The maximum depth of 92 feet was 

 observed near the middle of the wide eastern portion, about a quarter 

 of a mile from the east end of the loch and towards the northern shore. 

 The volume of water is estimated at 398 millions of cubic feet, and the 

 mean depth at 32 J feet. The loch was surveyed on August 8, 1902, but 

 the elevation of the la.ke-surface above the sea could not be determined. 



Loch a' Bhealaich is complex in conformation, including three deep 

 basins exceeding 50 feet in depth, separated by shallower water, the 

 shoalings coinciding with constrictions in the outline. The largest and 

 deepest basin is contained in the wide eastern portion of the loch, where 

 there is a 50-feet area nearly half a mile in length, by a quarter of a mile 

 in maximum width. Separated from this eastern basin by a short interval, 

 in which a maximum depth of 40 feet was observed, is a small central 

 50-feet area, based on soundings in 51, 55, and 55 feet, a quarter of a mile 

 in length. This central area is separated by a longer interval, in which a 



