THE FRESH-WATER LOCHS OF SCOTLAND. 
247 
ture at a depth of 50 feet than in either of the others. The temperature 
observed near the foot of the loch was lower at all depths than that 
observed towards the head, the difference amounting to 2° at 20 and 
at 50 feet, and to 0°’4 at 100 feet. The most pronounced fall in 
temperature was recorded between 50 and 100 feet towards the two 
ends of the loch, but between 30 and 50 feet in the central series (first 
column). The range of temperature shown by these serial observations 
is about 12°, while the extreme range of all the observations from 
surface to bottom during the week spent on the survey is over 17°. 
Loch Dilate (see Plate LIV.). — Loch Dilate (or Doilate) lies about 
1| miles to the east of the lower portion of Loch Shiel, into which it 
flows by the river Polloch entering Loch Shiel about 6 miles above 
its outflow. The ground between the two lochs is low, the fall from 
Loch Dilate to Loch Shiel being only 10 J feet, but high and moun- 
tainous country surrounds Loch Dilate in all other directions. The 
principal feeder is the river Hurich, which takes its rise in Lochan 
Dubh at the head of Glen Hurich, and after a course of 6 miles empties 
itself into the east end of Loch Dilate. The loch trends east and west, 
and is nearly IJ miles in length. It is widest towards the east end, 
where the maximum breadth is over one-third of a mile, the mean 
breadth being about one-seventh of a mile. Its waters cover an area 
of about 142 acres, or nearly a quarter of a square mile, and it drains 
an area fifty-eight times greater, or nearly 13 square miles. Forty-five 
soundings were taken in Loch Dilate, the maximum depth observed 
being 55 feet. The volume of water contained in the loch is estimated 
at 145 million cubic feet, and the mean depth at 23J feet, or 43 per 
cent, of the maximum depth. The loch was surveyed on July 8, 1902, 
and the elevation of the lake-surface above the sea, by levelling from 
bench-mark, was found to be 22‘0 feet. When levelled by the officers of 
the Ordnance Survey on October 16, 1867, the elevation was found to 
be 23’4 feet above sea-level. 
Loch Dilate forms a simple basin, the deeper water being centrally 
placed, and the contour-lines following approximately the outline 
of the loch. A sounding of 12 feet was recorded off the bay in the 
south-east corner of the loch, apparently surrounded by shallower 
water, though possibly continuous with the 10-feet area, but this is 
the only irregularity in the lake-floor indicated by the soundings. 
Along the central portion of the southern shore the contour-lines 
closely hug the shore, indicating a comparatively steep slope in this 
locality. A section along the central line of the loch from west to 
east is shown in section A-B on the map. The areas between the 
contour-lines drawn in at equal intervals, and the percentages to 
the total area of the loch, are as follows : — 
