8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



was desirable to have an equal distribution of the observations 

 throughout the months in order to study and to eliminate seasonal 

 influences. If, however, only those months had been used in which 

 both values were present, the main conclusions which follow would 



Table 3. — Mean Departures nf Pressure from Normal in Millibars ivith High 



Year 



Values in parentheses are interpolated from a synoptic chart (polar projection). 



not have been greatly impaired, although the quantitative values 

 would have been dififerent. 



The monthly values of pressure for the months when solar activity 

 was above normal were separated into zones of io° of latitude, 

 namely all between 8o°N. and 70°N., between 7o°N. and 6o''N., etc. 

 Because the statious were not equally distributed, but were mostly 



