294 POLAR PROBLEMS 



occasions almost identical readings were taken at Cape Evans and Cape 

 Adare, though the latter is 450 miles north. . . ; Pressures de- 

 crease to the east of the mountains — the large area of warmish water 

 in the Ross Sea undoubtedly tending to this result. . . . Sometimes, 

 however, when a 'low' lies over New Zealand, a 'high' covers Cape 

 Adare, as shown on December 23, 191 1. 



Cape Evans [77° S.] Pressure 29.955 



Cape Adare Pressure 30.004 



Terra Nova 500 miles NE. of Cape Adare Pressure 30.01 



"This leads to the inference of breaks in the great low-pressure belt 

 of the Southern Ocean. 



"During the voyage of the Terra Nova to and from Antarctica, it 

 was possible to trace the relation of Australasian and Antarctic pres- 

 sure curves. From December i, 1910, until December 23, 1910, 

 the ship was proceeding south from the Auckland Isles [lat. 50°] 

 to lat. 60° 31'. In general it may be stated that there was a distinct 

 resemblance in the barometric variations of the station at the Bluff, 

 N. Z. [46^°], and those at the ship until latitude 67° was reached. 

 On the return voyage correlation was again possible only between 

 these latitudes. The second voyage gave similar results. These 

 graphs showed a great similarity in the barographs at Cape Adare 

 and Cape Evans. . . . The Cape Adare (71°) and Cape Evans 

 (77^°) barographs are almost totally opposed to those obtained at the 

 Bluff. The Terra Nova graph of course starts in unison with the 

 Bluff and ends in unison with Antarctica. It apparently passes 

 through the region of maximum amplitude about 60° S. Summa- 

 rizing, we may state that Australasian weather does not reach to 

 Cape Adare (71°) but may extend south beyond the Antarctic Circle 

 (66°)." 



Simpson has shown the same sort of relation more accurately in 

 the accompanying chart (Fig. 8). Here he has compared pressure 

 changes in Australia and America with those at Cape Evans (which 

 he thinks may be taken as fairly typical of Antarctica) . 



Figure 8 shows that encircling the Antarctic is a region in which 

 all the correlation coefficients are negative. This zone lies approxi- 

 mately along latitude 40° S. There appears to be a seesaw of pressure 

 between the Antarctic and the belt of anticyclones. In other words 

 a month of high pressure over the Antarctic is accompanied by a 

 month of low pressure over latitude 40° S. To the north of Australia 

 is a belt where the pressure changes take place in the same sense as 

 the changes over the Antarctic. This belt was strongly developed in 

 I 902-1 903. 



Thus the Antarctic is one of the great "centers of action" of the 

 world. Changes here affect all the southern hemisphere. 



