SEA-FISHERIES LABORATORY. 165 
equilibrium, since the value for o, for a cooler layer is 
ereater than the value for the underlying layers, while 
for a warmer intermediate layer it is less than the value 
for the overlying ones. ‘This is well shown in the case of 
Station Vin July. The differences of o, for Stations VII 
and VIIT in May are within the hmits of experimental 
error. 
Similar cases of warmer or cooler intermediate layers 
were noticed in 1906 and 1907, but at quite different 
stations. 
From what has been said above it will be readily seen 
that these irregularities are of a purely accidental nature, 
and it is necessary to point out most emphatically that 
their existence in rare cases in the Irish Sea has nothing 
whatever to do with currents of either cold or warm water 
between the surface and the bottom. Such currents 
certainly do not exist. 
On the chart which accompanies this report the 
position of the isohaline lines has been indicated. All 
the observations made during 1906-1908 have been utilised 
in fixing the position of these lines, which, however, must 
only be considered as approximate, asthe observations, 
except at the ten ordinary stations, are far too few. The 
positions of the various stations at which observations 
have been made are indicated by small circles. The chart is 
meant to refer to the month of June, when the isohalines 
may be regarded as being in a sort of mean position. 
The extreme limit at which the Gulf Stream Drift 
ean be detected is approximately indicated by the 34:0 
isohaline on the chart. 
In conclusion, the plans for the hydrographie work 
for the year 1909 are given. 
Stations VIII, 1X and X will be given up, as it is con- 
sidered that as much information has been obtained from 
them as can be got, 
a 
