THE FRESH-WATER LOCHS OF SCOTLAND. 



59 



very much depressed. It is nearly 4 miles in length, with a maximum 

 breadth of three-quarters of a mile, and a mean breadth of one-third of a 

 mile. Its waters cover an area of about 851 acres, or 1| square miles, and 

 it drains an area of 41 square miles. The maximum depth of 206 feet 

 was observed at the widest part of the loch, at the junction of the two 

 limbs of the V. The volume of water is estimated at 2183 millions of 

 cubic feet, and the mean depth at 59 feet. The loch was surveyed on 

 August 21 and 22, 1902, when the elevation was found to be 129'0 feet 

 above the sea, nearly identical with that determined by the Ordnance 

 Survey officers on July 29, 1870, viz. 129-2 feet. The range in level is 

 4 to 5 feet, the water being lower than usual for the season at the time 

 of the survey, and might rise 3 or 4 feet higher, and fall a foot lower. 



Loch Danih is complex in conformation, there being three 25-feet 

 basins separated from each other by shallower water. The northern basin 

 is unimportant, with a maximum depth of 34 feet. The southern basin is 

 of simple form, over three-quarters of a mile in length, and encloses a 

 ]""-feet basin over half a mile in length, having a maximum depth of 

 135 feet. The central basin is the largest and deepest, being 2J miles in 

 length, and enclosing towards its southern end a small 200-feet basin, 

 elliptical in form, and nearly a quarter of a mile in length. At the 

 northern end of this central basin the 50-feet contour is irregular, shallow 

 water extending towards the middle of the loch, and approaching very 

 close to a small area slightly exceeding 100 feet in depth. Here a sound- 

 ing in 42 feet was recorded less than 30 yards from one in 115 feet, giving 

 a gradient of nearly 1 in 1. The shore-slopes to the east of the 200-feet 

 basin are fairly steep, a sounding in 84 feet having been taken about 

 40 yards from shore, and one in 134 feet about 90 yards from shore. 



Temperature Observations. Serial temperatures were taken in the 

 deepest part of the loch on August 21, and in the southern basin on 

 August 22, with the following results : 



These observations show a range of 14 D> 6 Fahr., the superficial layers 

 of water down to 50 feet being nearly uniform in temperature, while 

 between 50 and 100 feet there was a fall of 7 C and 7J 7 . In the deepest 

 part of the loch there was a further fall of 5J between 100 and 150 feet. 



