1904] Time Factor on Correlation between Barometric Heights. 405 



is desirable to take Wilmington earlier in order to predict for Halifax 

 later. For the southern pair of stations there is the same kind of 

 difference between the summer and winter results ; this seems to indi- 

 cate that the phenomenon is really connected with the season, and does 

 not depend on influences external to the Earth, since the summer for the 

 first pair is the winter for the second. Moreover, it is found that for 

 the two southern stations the change of pressure passes from north-west 

 to south-east, so that in predicting we ought to take St. Helena 

 earlier than Cape Town. The following tables give the correlations 

 obtained : 



Table I. Correlation of Barometric Heights at Halifax and 

 Wilmington. 



Table II. Correlation of Barometric Heights at Cape Town and 



St. Helena. 



* Positive when the reading is taken later at Halifax, 

 f Positive when the reading is taken later at Cape Town. 



