SEA-FISHERIES LABORATORY. 271 
He makes, however, the following remarks upon them 
which may be of use in connection with future work :— 
“ You will notice that there appears to be a complete 
reversal of conditions between August 24th and September 
12th. On August 24th, the water of lowest salinity 
(chlorine = 34°08) 1s at 62 fathoms, and the water of 
highest salinity (chlorine=54°12) is at 20 fathoms, and 
from 20 fathoms to the surface there is a slight decrease, 
but the general condition may be taken as high salinity 
above and low salinity below. On September 12th, the 
water of highest salinity (chlorine=354'07) is below and 
of low salinity (chlorine=33°96) above. In this case 
there appears to have been an inflow of cold, high salinity 
water along the bottom. The difference between the 
temperatures of the bottom samples is well marked, and 
is much more than would be accounted for by the 
difference of the surface temperatures. I think the 
hydrographical conditions in the neighbourhood would 
be of great interest if more frequent observations could 
be taken. 
“Tt would seem improbable from these results that 
that complete mixing of the water occurs which I under- 
stand has been found between the Isle of Man and 
Kngland—there is a very definite division of the water 
into layers which probably correspond to inflows of water 
along the deep channel: I] should think that current 
measurement work in the same locality might produce 
very interesting results. ’ 
TrpEs IN THE IRtsu SEA AROUND THE ISLE or Many. 
Amongst the factors that may have an effect on the 
variations of the plankton in space, time and quantity, 
the tidal streams still remain to be considered. 
The main lines of the tidal currents in the Irish Sea 
