48 



The first factor, consisting of the atmospheric pressure differences be- 

 tween two points taken across the line of drift of the ice on its journey 

 to the southward, is being furnished by the United States Weather 



Fig. 14. — November, 1926, anomaly of atmospheric pressure. Condi- 1^ 



t ions when reflected the following spring indicate more ice than normal 



Bui'eau in the form of monthly mean pressure records from^meteor- 

 ological stations scattered around the shores of the North Atlantic. 

 Observation points even in Greenland are now connected with the 



Fig. 15. — December, 1926, anomaly of atmospheric pressure. Conditions 

 when reflected the following spring indicate a normal ice season 



outside world by radio, a fact of great importance to the success of 

 this particular ice forecasting problem. Maps showing the anomaly 

 isobars, one map for each of the months, October, 1926, to Alarch, 



