232 THE ANTARCTIC. 



describes it in the latest edition of his Allgemeine 

 Erdkunde somewhat as follows : " The north-west re- 

 turn trade-wind of the southern hemisphere flows in the 

 upper strata of the air from the Equator to the Pole, and 

 according to theory it ought to blow due west to east 

 between the latitudes of 6o° and 70 S. To replace the 

 air sucked away from the Equator, air currents ought 

 to be observed on the surface of the earth ; these starting 

 from hio-h southern latitudes as west-south-west winds, 

 should in consequence of the earth's rotation gradually 

 assume a south-west and a south direction till at last they 

 became the south-east trade-wind. But instead of this 

 we find on the vast oceanic surfaces of the southern 

 hemisphere, between latitudes 40° and 6o° S., very violent 

 and constant west winds, the " Roaring Forties " of 

 English mariners. These owe their existence to the all 

 but total absence of extensive tracts of land, which would 

 create over large expanses of surface, in the southern 

 summer, local minima, and in the southern winter local 

 maxima of atmospheric pressure, and would thereby 

 essentially alter the distribution of the winds. We find, 

 on the contrary, in the southern summer, and still more 

 in the southern winter, a strongly-marked zone of high 

 atmospheric pressure, extending from 40° to 20 S., or 

 even to the Equator ; the winds which radiate from the 

 latter towards the south assume an easterly direction in 

 consequence of the rotation of the earth, and circle round 

 a zone of low atmospheric pressure which lies round the 

 South Pole from the fortieth parallel, its maximum of 

 depression coinciding possibly with the Antarctic circle. 

 As the winds must in general tend towards this minimum 

 of depression and towards its cyclones which pursue a 

 west to east direction, any influence exercised by the 

 constant west wind on the south polar lands must be 

 largely reduced, these regions being situated mostly to 

 the south of this belt of minimum of depression. If no 



