276 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



police duty does not permit of all the Coastal Stations 

 being regularly visited. Gaps in the various series of 

 data, therefore, occur, but in spite of these the figures are 

 of very considerable value. They have been abstracted 

 from the vessel's temperature log-book, and monthly 

 means have been calculated. These are given in Tables 

 II. and III. The first column under each Station gives 

 the number of observations made during each month ; the 

 second gives the range of dates on which the observations 

 were made; and the third is the mean temperature. In 

 plotting the latter data, the points graphed should, 

 obviously, not be the middles of the monthly periods, but 

 the median dates of the ranges shown in Col. 2. The 

 thermometers used for these observations are " Kiel " 

 instruments, graduated in fifths of a degree C. They 

 are regularly compared with a Bichter thermometer, 

 which again had been compared with a standard hydrogen 

 thermometer at the Charlottenburg Institute. 



Table IV shows the mean monthly sea-temperatures 

 at Nelson Buoy, Liverpool Bar, Great Orme's Head, Red 

 Wharf Bay, and Point Lynus, for the whole period 1909- 

 1912; and these data are also graphed in Text-fig. 1. 

 Some points of interest in these data may be noticed at 

 once. The range of variation of sea temperature is 

 variable; it is greatest (about 12° C.) at the Lancashire 

 Stations, Liverpool Bar, Nelson Buoy, and Piel Gas Buoy, 

 and it is least (about 9° C. to 10° C.) at the North Wales 

 Stations (Great Orme's Head, Eed Wharf Bay, and 

 Point Lynus). The dates of maximum and minimum 

 temperature also vary: at the Lancashire Stations the 

 minimum occurs about the third week in February, 

 while it occurs about the second week in Mai^h at the 

 North Wales Stations. The maximum also varies, 

 occurring about the first week in August in the case of the 



