THP] FRESH-WATER LOCHS OF SCOTLAND. 
403 
diameter, is fully half a mile, the mean breadth being over one-third of 
a mile. The superficial area is about 131 acres, and the contents 136 
millions of cubic feet. The drainage area is rather over 1 square mile.. 
Some small burns come in from the hills to the north, and the overflow 
is carried into the Doe burn, a mile to the south-west, and so into 
Loch Ness. 
Loch Tarff is shallow. Though it has a maximum depth of 89 feet, 
the mean depth is only 24 feet, nearly two-thirds of the area being less 
than 25 feet deep. The bottom is irregular, there being three separate 
basins over 25 feet in depth. Two of these are unimportant and lie 
FIG. 62. LOCH TARFF, LOOKING NORTH-EAST. 
(rhotof/raph hy Mr. G. WeM. From “ Proc. Pay. Soc. Ediu.,” by permission of the Conncil.) 
towards the south-east shore, with maximum depths of 27 and 42 feet 
respectively. The largest 25-feet area lies to the north-west of Eilean 
Ban, and stretches from south-west to north-east nearly across the loch, 
with a breadth of one-fifth of a mile. It encloses a small 50-feet area 
and a very small area of over 75 feet, both to the north of the centre 
and nearer the north-east shore, the maximum sounding, 89 feet, being 
found about half-way between the island and a rocky point north-west 
from it. 
T emperature Observations . — A series of temperatures taken in the 
deep part on April 25, 1903, showed a range of only 14 degrees, as 
shown in the following table : — 
