SEA-FISHERIES LABORATORY. 141 



shown by 1907, but the general effect is not convincing. What 

 the graph suggests is a possibility rather than a complete 

 demonstration. If the one poor year, 1910, is taken out there 

 is still no essential alteration. Therefore we see that 1907 

 exhibits so remarkable and characteristic a succession of 

 maxima and minima as to impress itself on the combined 

 temperature curves of the six following years. 



The daily fluctuations in temperature for the months June 

 to September for the same years have also been examined. 

 The smoothed curve plotted from the ten-daily averages for the 

 summer of 1907 (the year in which the January-March tidal 

 periodicity of temperature is so plain) rises sharply from 

 11-17° C. to a maximum of 1744° C. on July 27-28th, and 

 it falls again as rapidly. The slope of the corresponding curve 

 for 1910 is less, and the maximum is 15 '6° C. on August 4th. 



If the daily temperatures for the summer 1907 at More- 

 cambe Bay Ship be treated in the same way as in the case of 

 the earlier months there is, it is true, a marked fluctuation 

 above and below the mean line. Minor and irregular fluctua- 

 tions are more noticeable in the summer months, as might be 

 expected since, at this period, the air-temperature and solar 

 radiation act with greater effect on the surface water and so 

 bring about bigger fluctuations.* 



The curve, made as before, shows tidal maxima on 

 June 11th, August 10th, September 8th and September 22nd. 

 These are opposed to minima of temperature, which is the 

 condition one expects. The spring- tide maxima on June 26th, 

 July 11th and August 23rd, however, occur against parts of 

 the temperature curve, which are equivocal as regards the 

 occurrence of maxima or minima. The summer of the year 

 1907, then, does not fulfil the promise of its spring. 



The whole series of years 1907-12 and 1914 were next 



* See Robertson, " Observations of North Sea Surface Temperatures 

 and Salinities, 1904-5," North Sea Fisheries Investigations Committee Rept, 

 II (Northern Area), cd. 3358, 1907, p. 155. 



