2.80 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



get two equations, and by solving these simultaneously 



a and b can be determined ; a being ^ and b being 



At 



3m ! 



I being the half range. All this is very simple and 



2 I 3 



involves very little arithmetical work. What we really do 



dt° 

 is to approximate to , t° being the temperature and t the 



time. Only by taking moments about the means of the 

 periods in question can it be seen whether the tempera- 

 ture is decreasing, increasing, or is stationary, since 

 the " accidental " variations from day to day obscure the 

 trend of the curve. The daily increment of temperature 

 thus calculated is shown in Table VI. It is of practical 

 importance only in the months of May and November, 

 when the sea-temperature is changing rapidly. It need 

 hardly be applied in the months of February and 

 November. 



(2). The variation in temperature between various 

 points on the Holyhead to Calf of Man line of stations, 

 must also be considered. The stations are ten miles 

 apart, and Station 5 is about 10 miles distant from 

 Calf of Man, while Station 6 is about the same distance 

 from Holyhead. The difference of temperature in a 

 distance of thirty miles on some of the Lancashire lines 

 of Stations may be considerable, but it is quite small on 

 the line including Stations 5, 6, and 7. The mean 

 temperature of each station, at each cruise during the 

 years 1907-1912, has been calculated, and the differences 

 are shown in Table VII. The temperature of Station 6 

 is regarded, in each case, as T° C, and the difference 

 between this and the mean temperature of the adjacent 

 stations is shown. The greatest positive difference is 

 0'63° in August; and the greatest negative difference 

 0"33° C. in February. As a rule the sea-temperatures at 



