I9I5-] 



IN AIR CIRCULATION OF THE GLOBE. 



217 



ciently explained. As will be readily seen by reference to Fig. 8, 

 wherever Wilkes was within about three degrees, or some 200 miles, 

 of the inland-ice, the prevailing westerly winds were replaced by 

 southerly and southeasterly ones blowing off the ice. Mawson's 

 own observations leave us in no doubt whatever that this rule of 

 control holds for those margins of the continent which he explored 

 to the eastward of longitude 150° E. 



So apparent is the zone of control limited to a belt of 200 miles 

 breadth, at the time of year when Wilkes made his observations, 

 that the winds within and those without this zone for several de- 

 grees further, have been plotted in separate roses with results shown 

 in Fig. 9. 



Fig. 9. At the left; wind-rose based upon Wilkes's observations at 

 points distant less than 200 miles from the inland-ice ; and, at the right ; wind- 

 rose for a zone several degrees in width lying immediately outside the zone 

 of control. 



Capt. Davis of the Australian Antarctic Expedition cites an in- 

 teresting incident in the voyage of the Aurora off "Wilkes Land" 

 which indicates he was at the margin of the zone of control. *^*^ 



The wind observations made by the " Challenger Expedition " at 

 points which we now know to have been near the inland-ice,*'^ are 

 confirmation of this conclusion that the effect of the anticyclone 

 extends outward from the margins. Had the observations been 



6*a Home of the Blizzard, vol. 2, p. 40. 



^° Challenger Reports, Summary of Results, First part, chart 23. 

 those of the first German expedition in 1901-03,"^ offer valuable 



^^ W. Meinardus, " Deutsche Siidpol-Expedition igoi-os," Vol. 4 (Meteor., 

 Vol. 2), pp. 312-319. 



PROC. AMER. PHIL. SOC, LIV. 2l8 O, PRINTED AUG. 9, I9I5. 



