THE FRESH-WAITER LOCHS OF SCOTLAND. 279 



feet. The loch was surveyed on May 23, 1903, but the level could 

 not be determined ; from spot-levels the elevation is apparently about 

 feet above the sea. There are two deep basins in the loch, the 

 northern one having a maximum depth of 59 feet, while the southern 

 one includes the deepest water in the loch. It is curious to note near 

 the middle of the southern basin a shoal sounding in 22 feet surrounded 

 by much deeper water, and a short distance to the south an isolated deep 

 sounding in 70 feet. 



The following temperatures taken in the deepest part of the loch show 

 a range of less than 3 Fahr. from surface to bottom : 



Surface 49'8 Fahr. 



25 feet 49'3 



50 48-9 



60 47-9 



70 ., 47-0 



85 ... 46-9 



Black Lochs (see Plate CXXX.). The Black Lochs may be looked 

 npon as three expansions of the Lusragan burn (or rather four, since the 

 upper loch is cut into two basins), stretching for a distance of about 2 miles 

 in a north-east and south-west direction. The upper or northern extremity 

 is about a mile to the south-east of Connel ferry. The basins decrease in 

 depth on proceeding from north to south, the maximum depth of 36 feet 

 having been observed close to the north end, while the maximum depth in 

 the lower half of the upper loch is 32 feet, in the middle loch 27 feet, and 

 in the southernmost basin 22 feet. The lowest part is blocked for a con- 

 siderable distance by reeds, which are found also at various places along 

 both shores up to the head. They were surveyed on May 25, 1903, the 

 approximate elevation, judging from spot-levels, being about 80 feet above 

 the sea. The temperature of the surface water was 58-3 Fahr. 



LocJian nan Rath and Lochan na Beithe (see Plate CXXXI.) lie close 

 to the northern shore of Loch Etive, opposite Connel ferry. They seem to 

 have been formed by landslips. Lochan nan Rath covers an area of about 

 14 acres, and is cut into two basins by a ridge across the narrow central 

 part, on which there is only 2 feet of water. To the south-west of the 

 ridge a depth of 19 feet was recorded, while the maximum depth of 32 feet 

 was found to the north-east of the ridge. The temperature of the surface 

 water on May 26, 1903, was 62-2 Fahr. 



Lochan na Beithe forms a comparatively simple deep basin, covering an 

 area of about li' acres. The deepest part lies towards the western shore, 

 where four soundings exceeding 50 feet (maximum 58 feet) were taken. 

 The volume of water is estimated at 23 million cubic feet, and the mean 

 depth at 28 feet, or nearly one-half of the maximum. There is a slight 

 constriction near the middle, accompanied by a -slight shoaling of the 

 water. The surface temperature on May 26, 1903, was 58-4 Fahr. 



