of the Fishery Board for Scotland. 
369 
The season of greatest rainfall and most frequent storms falling in the 
low-sun period of the year tends to diminish the transparency of the water, 
and the greater dryness and calmness of the summer tend to increase the 
transparency apart from the greater penetrating power of the sun's rays 
from its high altitude and the clear sky. At the eastern end of each of 
the trawling stations the transparency is greater than at the western end, 
indicating that the chief cause of turbidity in the water comes from the 
west or riverward part of the Firth. 
Station IX. stands by itself in being fairly outside the Firth of Forth, 
and the average transparency is nearly the same at both ends, averaging 
4J fathoms in winter and 6J fathoms in summer. In both seasons it is 
higher than at any other station for t?ie same period, and the fact of the 
disc being visible 2 fathoms deeper in summer is probably mainly due to 
the greater altitude of the sun. 
The east end of Station VIII. conies close to the west end of Station 
IX., and the transparencies are about the same, but the west end coming 
near the shore at Canty Bay shows much less transparency. This may 
be due in part to dust blown olf the roads and fields by the prevailing 
south-westerly wind, which may often be seen tinging the water for a 
considerable distance from shore. 
The east end of Station VII. comes near the west end of Station VIII., 
and has a transparency slightly less ; its western end, near Fiddra, shows 
still slighter transparency. 
Station VI. is short, and the transparency of the water is the same at 
both ends, each being equally distant from the coast of Fife. 
Station V., stretching along the axis of the Firth, at the greatest 
possible distance from land, presents some features of interest. The 
transparency is practically the same at both ends, a fact of no small 
importance when taken in connection with the transparency being con- 
siderably greater than that at either VI. or VII. It shows that the 
turbidity of the water in the seaward portion of the Firth comes from the 
shores on the south and north, and is not carried down the middle of the 
channel by the tide from the muddy reaches of the Forth estuary. 
The eastern ends of Stations I. and III. are near Inchkeith, and in 
both the transparency is the same, 2 fathoms in winter and 2 J fathoms 
in summer. At the eastern end Station I. has water of greater trans- 
parency, but that of Station II. near the south shore of the Firth is the 
same as at its eastern end. 
Station II., curving round Largo Bay on the north, and Station IV., 
curving round Aberlady Bay on the south, are uniform in transparency 
at the two ends, but the transparency is greater in the former. 
Classifying the mean results we find that in the axis of the Firth at 
the farthest distance from land the depths to which a white disc is visible 
are as follows : — 
Off Inch- Between Sts. 
keith. Elie Ness Off Isle VIII., E. 
Sts. I.,W. and Fiddra. of May. and Open Sea. 
III., W. St. I.,E. St. v., W. St. v., E. IX., W. St. IX.,E. 
Summer, . 2-4 3-5 4-6 4 '8 6-2 6 '5 
Winter, . 1-9 2-4 3 8 37 4-2 4-4 
Range, . 0-5 11 0*8 I'l 2*0 2-1 
This shows a steady increase in transparency, and an increasing range 
between the penetrating effects of a low sun and a high sun. 
Contrasting with these the observations along the north shore we 
have : — 
2 a 
