220 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



REPORT ON TEMPERATURE OBSERVATIONS IN 

 THE IRISH SEA DURING THE YEAR 1909. 



By Jas. Johnstone. 



The main results obtained from the periodic hydro- 

 graphic cruises made during- 1909 are tabulated and 

 discussed by Dr. Bassett in a preceding Paper in this 

 Report, but I wish to give an account of the temperature 

 observations in particular, including data other than 

 those obtained in the course of the periodic cruises. 

 Special attention was directed towards obtaining a series 

 of records which might enable us to plot, with some 

 probability, the course of the isothermal lines in the 

 eastern part of the Irish Sea. This part of the hydro- 

 graphic work was regarded as of considerable importance, 

 apart altogether from the question of the circulation of 

 water in the Irish Sea and St. George's Channel, since it 

 is highly probable that the distribution and migrations 

 of some fishes are to be associated with the annual 

 temperature range on the various fishing grounds. 



The Data. As in 1907 and 1908, copies of the semi- 

 diurnal temperature observations made from the principal 

 West Coast Light Vessels have been supplied by the 

 Meteorological Office, and these are tabulated on page 245. 

 The observations made at 4 p.m. are alone considered. 

 Those from the Cardigan Bay Light Vessel are not 

 included since they were discontinued in 1909. Monthly 

 averages have been calculated. The latter have not been 

 graphed in this Report. 



The table immediately following that' just mentioned 

 gives the temperatures of the sea at the surface at the 

 Hydrographic Stations. In addition to the quarterly 

 cruises a series of observations were also made at inter- 



