8 SIEGE OF THE SOUTH POLE 
vailed it was recognised that far to the north of the 
pleasant temperate zone, which included the Mediter- 
ranean lands, there was a frigid zone of frightful cold, 
and to the south a torrid zone of frightful heat. The ac- 
ceptance of the spherical theory of the Earth involved the 
duplication of these zones in the southern hemisphere 
and their continuation as unbroken rings round the globe. 
It was very generally held that the frigid zones were unfit 
for habitation on account of the cold, and the torrid zone 
on account of the heat, while the temperate zones alone 
were habitable. Hence the Habitable World of the north 
temperate zone was separated from the Antichthone or 
habitable world of the south temperate zone by the burn- 
ing torrid belt, in which, as the equator was approached 
the heat and dryness of the Sahara grew worse and 
worse, until all life became impossible. The two habit- 
able worlds were believed to be separated by an impassa- 
