THE FRKSH- 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 

 1J 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 10J 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 1^ 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 : 



