628 
Proceedings of the Royal Society of Edinburgh. [Sess. 
with those on 28th August during a S.W. wind is instructive. At Inver- 
moriston the N.E. winds have much more “ gather ” than the S.W. winds. As 
a matter of fact, during strong N.E. winds observation was impossible, owing 
to the size and character of the waves. On the 5th, then, it is seen that 
although the wind was not strong (force 1 on scale of 1 to 10) the velocities 
of the currents measured ranged from 3‘2 to 16’9 cm. secs, from the surface 
down to 60 feet, all with a north-easterly direction. At 100 feet and 200 feet 
the directions were N. 8 W. and N. 10 W. respectively. On the morning of 
the 6tli, a day of variable breezes, there was a current of 3’9 cm. sec. from 
S. 39 W. at the surface, and the current at 30 feet was very variable. On 
the 28th there was a very strong S.W. wind, so that waves were breaking 
into the boat, yet as near the surface as 15 feet we have a current velocity 
of 11 2 cm. sec. from the N.E. and of 12 3 cm. sec. at 30 feet from the same 
quarter. The surface was too rough for an observation to be made there ; 
but a curious effect was noticed during a temperature observation : when 
the thermometer was sunk to a considerable depth the displacement of the 
line from the vertical was very marked in a direction opposite to that of 
the wind. 
The observation on 5th August above referred to was made during an 
isolated day of N.E. winds. From 14th to 20th August, however, there 
were continuous easterly winds, variable in strength. In no case is there a 
trace of a south-westerly current nearer the surface than 30 feet, and, save 
for a single observation on 17 th August, none nearer than 90 feet. All 
night observations from 14th to 15tli August show an average current of 
1*5 cm. sec. from N. 40 E. at 120 feet, and from 15th to 16th of 1*0 cm. sec. 
from N. 31 E. at 180 feet. But it is evident that the latter observation was 
made on the upper margin of the return current, for while ten balls indicated 
a N.E. current, there were also three indications of currents N. 60 W., S., 
S. 40 W. Two days later, on the 17th, there are indications of a return 
current from 30 to 60 feet. The rising of the return current during the 
continuance of N.E. winds is clearly shown by the overnight observations 
commenced on 15th and 17th August, viz. : — 
Date. 
Depth. 
Average 
Current 
Velocity. 
Directions. 
Aug. 15-16 
180 feet 
DO cm. sec. 
10 N. 31 E. 70 ; jN. 60 W. 
jS. ; L S. 40 W. 
„ 17-18 
150 „ 
1*2 „ 
„s. 10 W. 60 ; X N. 20 E. ; 
,N. 20 W. ; ,N. 40 E. 
