348 BATHYMETRICAL SURVEY OF 



Monar. A terrace of gravel surrounds the loch, except on the northern 

 shore, where the hill an Carnach rises steeply from the lake-shore. 

 There is a large island named Eilean a' Mhuilinn near the east end, and 

 two smaller islands at the mouth of the inflowing river at the west end. 

 The loch trends in an east-north-east and west-south-westerly direction, 

 and is nearly a mile in length, with a maximum breadth in the centre 

 exceeding one-third of a mile, whence it narrows towards the two ends. 

 The superficial area is about 100 acres, and the area of land draining 

 directly into it is about 37f square miles, but since it receives the 

 overflow from Lochs Monar, an Gead, an Tachdaidh, and Calavie, its 

 total drainage area is nearly 88 square miles an area 550 times greater 

 than that of the loch. The maximum depth of 94 feet was observed in 

 the wide part of the loch towards the northern shore. The volume of 

 water is estimated at 150 million cubic feet, and the mean depth at 

 over 34 feet. The loch was surveyed on October 12, 1903, when the 

 elevation was determined, by levelling from bench-mark, as being 

 417-65 feet above the sea; when visited by the Ordnance Survey officers 

 on June 1, 1866, the elevation was found to be 417'5 feet above sea- 

 level. A drift-mark was observed 5 feet above the surface of the 

 water on the date of the survey, when the level was about its normal. 



Loch a' Mhuilinn consists of a deep central basin, with two small 

 subsidiary shallow basins at the two ends, as shown in the longitudinal 

 section on the map. Towards the west end, immediately to the north 

 of the island at the mouth of the inflowing river, a depth of 25 feet was 

 recorded, separated from the main basin by a rise of the bottom, on 

 which a maximum depth of 12 feet was observed. Towards the east 

 end, between Eilean a' Mhuilinn and the mouth of the outflowing river, 

 a depth of 24 feet was recorded, separated from the main basin by a 

 depth of 3 feet in the narrows between the island and the northern 

 shore. In the main deep basin the contour-lines are continuous and 

 the bottom regular, seven soundings in depths exceeding 80 feet having 

 been recorded to the west and south-west of Eilean a' Mhuilinn, two of 

 them in depths exceeding 90 feet. The area of the lake-floor covered 

 by less than 50 feet of water is about 72 acres. 



Temperature Observations. The following series of temperatures 

 taken in the deepest part of the loch shows that the body of water was 

 nearly uniform in temperature on the date of the survey, the extreme 

 range observed being less than 1 Fahr. : 



Surface 47'2 Fahr. 



10 feet 47'0 



25 46-8 



50 46'6 



90 464 ,, 



Loch Butiacharan (see Plate LXXXII.). Loch Bunacharan (or 



