230 THE ANTARCTIC. 



quantity, whilst the radiation of heat into the atmosphere 

 and the aerial currents and climatic influences caused 

 thereby depend on the local distribution of land and 

 water. Accordingly, an interchange of air, such as, 

 for example, takes place between western Europe and 

 the Atlantic, effecting so considerable a rise in the mean 

 annual temperature of north-western Europe, could not 

 possibly take place there. This is clearly exhibited by 

 the charts of the distribution of temperatures and of atmos- 

 pheric pressure. The isothermal lines and the isobars 

 show but few and slight curves, and instead we observe 

 a pronounced parallelism between both kinds of climatic 

 curves, which, although mainly conjectural, are probably 

 enough in accordance with actual facts. The climate of 

 Antarctic regions proper can consequently either not be 

 inferred at all, or only to a slight extent from that of the 

 surrounding ocean, but it must be based on the thermic 

 condition of the country itself, on the prevailing winds, 

 and finally on the general circulation of the atmosphere 

 over the globe. 



The prime and weightiest factor of the south polar 

 climate is the geographical position of those regions. As 

 has just been observed, it is purely oceanic, but this 

 characteristic is not fully distinctive, as it is shared by 

 every island, and even among the continents, primarily 

 by Australia, then by South America, and at bottom 

 by all the continents of the world. But that which 

 distinguishes the Antarctic regions from all other insular 

 masses of land, and the effect of which has already 

 been faintly indicated, is its circumpolar oceanic position. 

 This alone prevents the existence of any essential con- 

 trast in temperature between the several meridians, which 

 leads to convection-currents of the air, and of the waters 

 that depend on them ; it alone conduces to the almost 

 symmetrical distribution of atmospheric heat and pressure 

 which is graphically exhibited by the uniform zones of 



