190 
Part III. — Ninth Annual Report 
Tarbert (Jura), Gruinart (Islay), and Killisport are short lochs, and 
permit very readily of an interchange of water with the neighbouring 
open sea. Wherever the entrance to the lochs was narrow and long, 
the surface density was lower, and especially was this the case where 
the loch receives land water from a large drainage area. 
There is less variation in the bottom densities ; but here, again, another 
factor in addition must be taken into consideration, viz., the depth of 
the loch in question. Wherever the Ibch is shallow, the tendency, 
according to the laws of diffusion, is naturally for the bottom density 
to approximate to that of the surface. The only instance in which I 
found the density of the bottom water less than the surface was in the 
case of Rum (3 miles westwards), where water taken from 47 fathoms 
was of slightly less specific gravity than surface water. The average of 
the bottom densities is nearly 27. These observations were taken by the 
system in use at the Board's regular observing Stations and at the Kiel 
Stations of the German Government. 
Temperature observations were taken by the reversing thermometers 
in ordinary use on board the 'Garland,' and these indicate the actual 
temperatures of the water 18 inches below the surface and 2 or 3 
feet above the bottom. Where they differ from the temperature at 
which the specific gravity observations were determined, this difference 
is due to the rise of temperature which almost invariably takes place 
between the time when the water is withdrawn from its place in the sea 
and the reading of the hydrometer. The following are the temperatures 
for the lochs of which the densities are previously given (the dates being 
the same and the time approximately so) : — 
Temp, of Sea. 
Depth. 
Temp, of Air. 
Transparency. 
Surface. 
Bottom. 
° C. 
°C. 
Fathoms. 
" Fahr. 
Fathoms. 
Loch Creran, . 
11-2 
10-1 
8^ 
54-3 
2 
>»»>•• 
11-6 
10-5 
7 
55 
2i 
,, Spelve, N., . 
10 
9-8 
7 
53 
H 
>) n S.j, . 
10 
9-5 
7 
58 
2i 
10-8 
10-2 
7 
57 
3| 
10-6 
9-8 
20 
63 
8i 
,, Sunart, . 
11-1 
10-1 
8 
62-5 
Scridain, 
12-9 
10-7 
9 
61 
3 
-na-Keal, 
12-25 
10-75 
4i 
57-5 
,, Moidart, 
107 
10-5 
4i 
56-5 
4^ 
Aylort, . 
10-8 
10-8 
2 
65 
Bottom. 
,, Harport, 
11-7 
11-3 
7 
60 
H 
11-8 
11-7 
7 
54 
5 
\\ Vattin, . 
11-7 
11-6 
4i 
54-25 
4i 
,, Dimvegan, 
11-5 
11-1 
56 
3^ 
Greshoriiish, . 
10-5 
10-8 
3 
56 
Bottom. 
>) »> 
10-8 
10-8 
4 
58 
3 
Snizort, 
Tarbert (Jura), 
10-5 
10-4 
45 
55-8 
6i 
13-2 
13-6 
7 
56 
3i 
3 
Gruinart, 
1T25 
11-25 
H 
54-75 
Lochiudaal, . 
13 
12-8 
3i 
55 
Bottom. 
Loch Kyan, S., 
14-7 
14-5 
3 
52 
Bottom. 
„ Mid, . 
14-2 
14-1 
6 
55 
2 
West L. Tarbert, E., 
13-8 
13-7 
2i 
59-5 
Bottom. 
„ w., 
14-1 
12 
13i 
58 
5 
Loch Killisport, E., 
11-3 
11-3 
H 
53 
Bottom. 
W.. 
11-3 
10-9 
12 
49 
6 
„ Swen, E., 
13-7 
12 
8 
51 
4i 
M »j S.E., . 
13-8 
11-8 
6 
51 
4 
