THE FRESH-WATER LOCHS OP SCOTLAND. 69 



shallow, the maximum depth being 20 feet, and the mean depth 7J feet. 

 The superficial area is about a !84 acres, of which 74 per cent, is covered by 

 less than In feet of water. The volume of water is estimated at 61 

 million cubic feet, and the drainage area extends to 30 square miles. The 

 elevation above the sea could not be determined, but the Ordnance Survey 

 maps give it as 1<>24 feet, though the date is not indicated. 



There are three basins in which the depth exceeds 10 feet : one at the 

 east end enclosing the maximum depth of the loch (20 feet), one in the 

 central part of the loch having a maximum depth of 12 feet, and one at 

 the west end having a maximum depth of 16 feet, taken close to a 

 promontory projecting from the northern shore. 



Temperature Observations. Serial temperatures taken in the deepest 

 part of the loch on May 19, 1903, gave the following results : 



Surface 53-0 Fahr. 



10 feet ... 50-0 



15 46-2 



20 46-0 



The range of temperature from surface to bottom was 7, the greatest 

 fall being one of 3'8 between the depths of 10 and 15 feet. 



Lochan na SalacJi Uidhre (see Plate XXVI.). This loch lies to the 

 west of Loch a' Bhaillidh, and is most irregular in outline, consisting of 

 several divisions varying in size, connected by short channels. The two 

 easternmost divisions could not be surveyed, being cut off from the main 

 loch by a narrow channel, with a fall of about 5 feet. There is also a 

 slight fall of 6 inches to a foot in the channel leading into the westernmost 

 division of the loch, though the Ordnance Survey maps give the same level 

 (In22 feet above the sea) for the entire loch west of the falls. On the 

 whole, the loch is shallow, with many islands and boulders. The length 

 of the portion surveyed is nearly 2 miles from east to west, and the 

 maximum breadth over one-third of a mile. The area is about 245 acres, 

 of which 86 per cent, is covered by less than 10 feet of water. In nine 

 places soundings deeper than 10 feet were taken, mostly restricted areas 

 varying from 10 to 12 feet in depth, and only in three places were depths 

 of 2' > feet and over recorded: (1) in the narrower portion between the two 

 peninsulas called Rudha Dubh-mor and Rudha Dubh-beag at the east end, 

 where a sounding in 20 feet was taken ; (2) to the west of Rudha Dubh- 

 beag, where soundings in 22 and 26 feet were taken ; and (3) in the 

 westernmost division, where soundings in 23, 25, and 29 feet (the maximum 

 depth recorded) were taken. The volume of water is estimated at 70 

 million cubic feet, and the mean depth at 6J feet. The area draining 

 directly into the loch is nearly 9 square miles, but as it receives the 

 overflow from Loch a' Bhaillidh, the total drainage area is about 38 J 

 square miles. 



Temperature Observations. Serial temperatures taken on May 19, 1903, 



