1898-1902. No. 4.] 



PRESSURE. DAILY PERIOD. 



53 



November. 



December. 



The last column in the Tables gives the number of days in each 

 month from which bi-hourly observations have been available for the 

 determination of the daily period. It will be seen that all the months 

 from November to June are represented by fully four years, while the 

 other months, — particularly August — or the months in which the 

 Fram was under way, are less favoured in this respect. The means 

 for these latter months have been computed, the numbers being given 

 a weight proportional to the number of observing days. They are desig- 

 nated as Weighted (W.) Means. 



The last of the above Tables gives the means for the meteorologi- 

 cal seasons (Dec— Febr. etc.) and for the year. 



Treating the bi-hourly deviations from the daily mean by harmonic 

 analysis, we find the values of the constants a^ A^ a^ A^ in the 

 formula 



p^ — p^=. a, sin (Ai + t) + a^ sin (A^ + 2^ 



t reckoned from midnight. 



