16 
BATHYMETRICAL SURVEY OF 
217 acres, or one-third of a square mile, and the drainage area is nearly 
9| square miles. The maximum depth of 8 feet was recorded at six 
soundings in the northern half of the loch. The volume of water is 
estimated at 49 million cubic feet, and the mean depth at feet. The 
loch was surveyed on October 10, 1902, when the elevation of the lake- 
surface was found by levelling from bench-mark to be 153*7 feet above 
the sea; when visited by the Ordnance Survey officers on February 18, 
1870, the elevation was 155*5 feet above sea-level. The height of the 
water is regulated by a sluice, and the cracked peaty soil at the margin, 
with boulders covered by a luxuriant growth of Fontinalis, indicated a 
very recent fall of about 2 feet from a former long-maintained level. 
Like the other lochs in this locality, Loch Hempriggs is a shallow, 
flat-bottomed basin, over two-thirds of the lake-floor being covered by 
more than 5 feet of water, and the mean depth of the entire loch is about 
65 per cent, of the maximum depth. The temperature of the surface 
water on the date of the survey was 48°*9 Fahr., while readings at depths 
of 3 feet and 7 feet gave in each case 48°*5. 
