THE FRESH- WATER LOCHS OF SCOTLAND. 
265 
maximum deptR of 217 feet, and the largest one extending from north 
of the Douglas water delta as far as Ardvorlich, about 2 miles from the 
head of the loch, enclosing all the deeper basins. The 300-feet and 
400-feet contours are continuous, and enclose areas respectively over 8 
and nearly 7 miles in length, lying to the north of the Douglas water 
delta. The 500-feet basin is cut in two portions by a ridge, on which the 
greatest depth is 483 feet, crossing the loch just south of Tarbet, the 
smaller southern portion being over a mile in length, and having a 
maximum depth of 564 feet, while the northern portion exceeds 3 miles 
in length and encloses the maximum depth of the loch. The 600-feet 
basin is a mile in length, and lies to the north of Tarbet, the maximum 
depth of 623 feet having been recorded little more than half a mile to the 
north-east of Tarbet island. 
The survey of Loch Lomond occupied from May 30 to June 19, 1903. 
On commencing work the elevation of the surface of the water was 
determined by levelling from two bench-marks as being 23’9 feet above 
mean sea-level, and during the progress of the survey the water slowly fell 
to the extent of more than a foot, but all the soundings were reduced to 
that datum level; the elevation determined by the officers of the Ordnance 
Survey on October 12, 1896, was 26'9 feet above the sea, or 3 feet higher 
than on May 30, 1903. A drift-mark measured on June 9, 1903, was 
found to be 7J feet above the water surface, so that the range in level is 
considerable. 
Temperature Observations . — The temperature conditions in Loch Lomond 
have been studied by Mr. J. Y. Buchanan and others, and for purposes 
of comparison half a dozen serial observations taken during the survey 
are given here, arranged geographically from north to south. 
Seeial Tempeeatuees in Loch Lomond. 
Depth 
iu feet. 
’ June 2. Off 
Ardvoi'lich. 
Depth 205 feet. 
June 11. Off 
Culness. 
Depth 622 feet. 
June 18. Between 
the islands of 
Torrinch and 
Inchmoan.i 
Depth T2 feet. 
June 16. Be- 
tween Creinch 
island and 
Inchmurrin. 
Depth 60 feet. 
June 19. Off 
eastern side of 
Inchmurrin. 
Depth 55 feet. 
June 13. Southern 
end. Nearly a 
mile south of 
Inchmurrin. 
Depth 62 feet. 
o Fahr.' 
o Fahr. 
° Fahr. 
! ° Fahr. 
i ° Fahr. 
° Fahr. 
0 
46-0 
58T 
57-4 
1 56-6 
57-2 
59-5 
10 
45-8 
— 
1 
1 56-6 
— 
— 
15 
— 
— 
56-6 
— 
58-3 
20 
45-2 
57-8 
— 
57-2 
— 
25 
45-2 ■ 
— . 
55-3 
— 
— 
— 
30 
— 
52-7 
— 1 
56-0 
57-0 
56-8 
35 
— 
— 
52-0 1 
— 
— 
— 
40 
— 
46-3 

— 
53-5 
52-9 
50 
44-5 
45*8 
50-5 i 
— 
51-2 
— 
60 
— 
— 
— 
55-8 
— • 
49-6 
70 
— 
— 
49-4 
— 
— 
— 
100 
44-0 
43-8 
— 
— 1 
— 
— 
200 
42-8 
42-7 
— 
— 1 
— 
— 
300 
— 
42-2 

— 
— i 
— 
400 
— 
42-2 
— 
— 
— . 
— 
500 
— 
42-2 
_ 
— 
— 
— 
600 
— 
42-2 
— 
— 
— 
