216 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



curves in the Irish Sea speak, I think, for themselves. It 

 would hardly be possible to draw the isohalines 

 substantially different from the way in which they are 

 drawn on the charts, and it is clear that such a distribu- 

 tion of salinities can only be explained by a flow of water 

 from South to North. 



The figures on the charts refer to surface salinities, 

 but the Irish Sea is practically homosaline throughout, 

 and where any differences of salinity with depth do occur 

 they are small, and do not affect the above conclusions. 

 The isohalines show very plainly how the northward 

 flowing current tends to flow along the eastern side of the 

 Irish Sea. They also show that a great deal of the water 

 flows round to the east of the Isle of Man (as indicated 

 also by the tides). In this last connection it is most 

 interesting to note that whereas the spring maximum of 

 the salinities is well marked at Stations V, VI, VII and 

 XI, between the Calf of Man and Holyhead, it is 

 practically undetectable at stations on the 54° of latitude 

 West of the Calf of Man. This probably means that 

 nearly all the water flowing through the Irish Sea passes 

 to the East of the Isle of Man. It is to be noted that in 

 my report for 1908, where I also referred to this last 

 point, there is an error in the third paragraph from the 

 bottom of the last page but one — " the 34 - isohaline on 

 the chart " should read " the dotted line on the chart." 



The curves of equal temperatures for the surface 

 water of the Irish Sea during 1909 have been drawn and 

 discussed by Mr. Johnstone, and are reproduced in 1he 

 plates illustrating his paper in the present report. These 

 isotherms show even more strikingly than the isohalines 

 the direction of flow of the water. In particular they 

 clearly show the current bending round to the East of the 

 Isle of Man. 



