370 
Part III. — Ninth Annual Report 
Off Inch- 
keith. Kirkcaldy. Leven. St Monans. Anstruther. 
St. I., W. St. II. W. St. II., E. St. VI., W. St. VI., E. 
Summer, . . 2*4 3-2 3 '4 4*1 4*1 
Winter, . . 1*9 2*5 2-5 27 2-6 
Range,. O'S 0-7 0*9 1-4 I'S 
and with those along the south coast : — 
S.-W. 
Off Mussel- Fiddra. North of Bass . 
burgh. Aberlady. St. VII., of Bass. St. VIII., 
St. IV., W. St. IV., E. III., E. W. St. VII. E., W. 
Summer, . 2*0 2-0 2-4 2-6 3-6 3*8 
Winter, . 1*6 1 '8 2-0 2-0 27 3-3 
Range, . 0-4 0-2 0-4 0*6 0-9 0-5 
This comparison shows that the water is clearest along the axis of the 
Firth, increasing rapidly in transparency toward the sea ; and that in this 
region the range of transparency between summer and winter is very 
marked. Along the north shore the transparency is somewhat less, and 
the range between the limits of visibility in summer and winter is less. 
Along the southern shore the transparency is much less, and the increased 
power of the summer sun produces the least increase in the depth of 
visibility, which was anywhere observed. 
The bearing of transparency of water on the amount of light pene- 
trating into the depths on practical fisheries is considerable. Probably 
the fish in the centre and north side of the Firth can see further through 
the water than those on the south side, and one might even venture the 
suggestion that nets would escape detection more readily on the south 
side than on the north. It might be worth while to compare the species 
and numbers of fish caught with these very clearly marked differences of 
transparency. 
Observations on the West Coast. 
There are as yet only two stations in the Clyde Sea Area where observa- 
tions of temperature have been carried on for a little over a year — 
Ardrishaig and Brodick ; and two stations on neighbouring lochs where 
the work was begun in January 1891 — West Loch Tarbet and Loch Ryan. 
The two latter call for no remark here as the observations have not been 
continued long enough to allow one to judge of their value. The ten- 
day means are given in Table VIL, the monthly means in Table VIII. 
The other observations are, however, full of interest, and cast much light 
on the contrast betw^een the physical condition of the water in the Clyde 
sea area and on the east coast. 
Ardrishaig. — Observations commenced here on 20th January 1890, 
and have been continued with great regularity. The surface temperature 
is observed at 8 a.m. and 3 p.m. from the north-eastern end of the stone 
pier, where the depth of the water at low tide is about one fathom. The 
situation is the best available, being always in the shade, and therefore little 
affected by the heating of the stonework in summer. There is reason to 
fear, however, that the minimum temperatures recorded in winter are too 
low, the water being probably chilled by contact with the cold masonry. 
Loch Gilp, at the mouth of which Ardrishaig is situated, is a short branch 
from Loch Fyne, or rather a prolongation of what I have elsewhere* 
termed the Central Arran Basin. The water is shallow, and at the upper 
end of the loch very extensive sands are uncovered at low tide. Hence 
at ebb tide the water, which is carried past Ardrishaig Pier, is probably 
chilled in winter and heated in summer in consequence of having been 
* ' On the Physical Conditions of the Clyde Sea Area,' read to the Royal Society of 
Edinburgh, May 1891, and recommended for publication in the Transactio7is. 
