NO. 4 TEMPERATURE VARIATIONS IX THE NORTH ATLANTIC 45 



to or in some degree obliquely to them his consequence would be 

 erroneous and his temperatures anomalies for the twelve stations 

 would prove little either in one direction or the other. 



Petersen found further that the deviations in the surface tempera- 

 tures of the North Atlantic Ocean have a well marked tendency to 

 swing about an axis in the center of the ocean at about 40° west 



/Z // /O 9 8 



/ 



Figure 14. Isopleth diagram of the average temperatures for each month 

 of the year (J-D ) at T. Petersen's twelve stations (i to 12) along the abscissae. 



longitude in such a way that the temperature deviations eastward 

 and westward of this axis are of opposite sign. Petersen's obser- 

 vational material is, however, not sufficiently complete and satisfac- 

 tory to prove such a conclusion, particularly for the w^estern fields. 

 Petersen's investigations have interest for us in that they embrace 

 all the months of the year, and we can therefore follow the march 

 of the average temperatures from month to month. In figure 14 



