480 Proceedings of Royal Society of Edinburgh. [sbss. 
showed that the temperature fell from 62 o, 0 near Yarmouth Boads 
to 58 O- 0 near the Wash, and to 56°*5 off Scarborough; hut from 
this point northward to Lerwick, the temperature was virtually a 
constant, being 55 0, 5 on entering Bressay Sound. The area over- 
spread by this substantially uniform temperature on the east coast 
of Great Britain is virtually coincident with the southward flow of 
the tidal current from the Atlantic as determined by Dr Fulton. 
Observations of the surface temperature of the sea on these coasts 
amply confirm those made by Dr George Keith in 1865. 
The wind also has an important influence on the currents of 
the North Sea. The winds have been observed by the Scottish 
Meteorological Society’s observers from 1856, and the averages 
during these forty-three years drawn from observations at about 
sixty stations show that the average number of days the different 
winds have prevailed during the year are : — 
N. 
30 Days 
s.w. 
66 Days 
N.E. 
28 
}> 
w. 
69 „ 
E. 
39 
)) 
N.W. 
39 „ 
S.E. 
32 
J5 
Calm 
25 „ 
S. 
37 
55 
Thus the prevailing winds are W.S.W. ; and the observations 
further show that these are by far the strongest of the winds. 
Now these strong W.S.W. winds, considered as producers of surface 
currents of the sea flowing from the British coasts towards 
Denmark, the Skaggerrak, and Norway, are necessarily most effec- 
tive near the southern limits of the tidal currents from the north 
or about the Wash, and thence eastward. 
This is well shown by Dr Fulton’s chart of the observed currents, 
on which it is seen that the floats crossed the North Sea between 
latitudes 55° to 53° N. ; and thence, curving round, impinged on 
the Danish coast near Faro and round to Skagen ; and thence 
diverted through the Skaggerrak ; and thence northward, keeping 
close to the Norwegian coast as far as the Loffoden Islands. The 
prominent characteristic of this current chart is that north of lati- 
tude 55° N., few or none of the floats are represented as having 
crossed the North Sea. North of this parallel the strongest inflow- 
ing tidal currents keep near the east coast of Great Britain, and the 
