The Scientific Advantages of an Antarctic Expedition. 445 



As regards the southern hemisphere, Professor Davis states that : 



" In the southern hemisphere the circumpolar eddy is much more 

 symmetrically developed." Again, " the high pressure that should, 

 result from the low polar temperatures is therefore reversed into 

 low pressure by the excessive equatorward centrifugal force of the 

 great circumpolar whirl ; and the air thus held away from the polar 

 regions is seen in the tropical belts of high pressure" (pp. 110, 111)- 



The meaning of this is that the remarkable low-pressure region 

 of the southern hemisphere is continued southward to the South 

 Pole itself, the pressure dimiaishing all the way ; and that in the 

 region of the South Pole the air currents poured thitherwards along 

 the surface of the earth ascend and thence proceed northwards as 

 upper currents of such enormous intensity and volume that they 

 pile up in the tropical region of the southern hemisphere a mean 

 sea-level atmospheric pressure about an inch and a half higher than 

 the sea-level pressure near the South Pole whence it has started. 



Now, to bring the matter to the business which this meeting of 

 the Royal Society has in hand — if this theory were true and sup- 

 ported by the facts of observation — it is plain that no meteorologist 

 could signify his .approval of any scheme that could be proposed for 

 exploring the Antarctic regions, it being obvious that these strong 

 west-north- westerly winds, if they blow vertically round and in upon 

 the pole, heavil}^ laden, as they necessarily would be, with the aqueous 

 vapour they have licked up from the Southern Ocean, would over- 

 spread Antarctica with a climate of all but continuous rains, sleet, 

 and snow which no explorer, however intrepid and enthusiastic, could 

 possibly face. 



But is this the state of things ? Let it be at once conceded that, 

 as far south as about 55° lat. S., the prevailing winds and the 

 steadily diminishing mean pressures on advancing southward, fairly 

 well support the theory. South of this, however, southerly and 

 south-easterly winds begin to increase in frequency, until from 

 60° lat. S. into higher latitudes, they become the prevailing winds. 

 This is abundantly shown from the winds charted on the maps of 

 the " Challenger " Report, as well as from the unanimous experience 

 of all that have navigated this region from Ross to the present time. 

 Thus the poleward blowing winds from west-north-west in these 

 summer months stop short, distant at least 30° of latitude from the 

 South Pole. 



These prevailing south-easterly winds necessarily imply, as has 

 been shown in the analogous case of the North Pole, the existence 

 of a more or less pronounced anticyclone overspreading Antarctica ; 

 which in its turn necessarily implies the existence of upper currents 

 from the northward, blowing towards and in upon the polar region 

 to make good the drain caused by the surface out-blowing south- 



