THE FRESH-WATER LOCHS OF SCOTLAND. 
383 
was determined from bench-marks as being 52 ’6 feet above the sea, 
and to this datum-level all soundings have been reduced. A levelling- 
staff was erected first at Fort Augustus, then at Invermoriston, Foyers, 
and Temple piers, and the height of the water on this staff was read 
daily during the progress of the survey, so that the variations in level 
from day to day, and the variations from the starting-point, were readily 
known. These staff readings showed that the water fell gradually but 
irregularly, and by April 15 it was 1 foot lower, and by the 18th it was 
IJ feet lower, than on April 1. 
Loch Ness proper may be said to extend from the head of the 
loch at Fort Augustus to the narrows at Bona ferry, a distance of 22| 
miles following the axis of maximum depth. This figure is inferior 
to the length of Loch Awe (25 J miles), and slightly in excess of the 
length of Loch Lomond (22| miles) ; if we regard the small basin of 
Loch Dochfour, which is continuous with Loch Ness at its northern 
end, as forming part of the loch, then the total length from the exit 
of the river Ness to the head of the loch, is about 24J miles. 
In this place it is proposed to include Loch Dochfour in dealing with 
Loch Ness; it is a basin about IJ miles in length, with a maximum 
depth of 50 feet in the wide central portion, whence it narrows towards 
the two ends, the southern narrows leading into Loch Ness, and the 
northern termination being divided into two branches, the eastern 
branch forming the river Ness, and the western branch the continuation 
of the canal. With a strong south-westerly wind there is a surface 
current from Loch Ness into Loch Dochfour through the narrows at 
Bona ferry, and, if long continued, the water becomes banked up in 
Loch Dochfour, and gives rise to a return current along the bottom into 
Loch Ness; with a strong wind from the north-east the surface current 
sets in the opposite direction, i.e. from Loch Dochfour into Loch Ness. 
Cut off from the western margin of Loch Dochfour, by embankments 
carrying the towing-path for the canal, are two small basins, one called 
Abban water, having a maximum depth of 9 feet, the other without a 
distinctive name, having a maximum depth of 23 feet; they stand at 
the same level as Loch Dochfour, the water evidently percolating 
through the embankments. 
Loch Ness may be said to be fairly uniform in breadth, though 
varying to some extent, but on the whole its shore-line is very regular 
when compared with other large lochs. The upper portion between 
Fort Augustus and Foyers for about 10 miles is under a mile in width, 
except at the opening of Glen Moriston, where the breadth slightly 
exceeds a mile. The portion between Foyers and Castle Urquhart for 
about 5 miles is almost exactly a mile in width, while the lower portion 
between Castle Urquhart and Torr point for about 5 miles exceeds a 
mile in width. The widest part of the loch is at Urquhart bay, from 
the mouth of the river Enrick due east to the opposite shore, where the 
