386 
GEOGRAPHICxlL SYSTEMS. 
ers. of this school av/are of its extent, that Pliny 
pronounces it to be the least of the three conti- 
nents, and inferior to Europe.* 
Another hypothesis, eminently characteristic of 
this school, was probably suggested by African 
phenomena. This was the existence of an unin- 
habitable torrid zone. To those who saw this 
continent, even north of the tropic, spread into 
an expanse of burning sand, which reflected a heat 
scarcely compatible with animal life, it naturally 
appeared that an exposure to the sun's still more 
powerful influence must be inevitably fatal. The 
borders of the desert would probably have been 
fixed as the point beyond which life could not 
pass. But the long course of the Nile, and the 
celebrated kingdom of Ethiopia, proved the ne- 
cessity of looking still higher. Upon the Nile, 
therefore, they measured the habitable world of 
Africa, and fixed its limits at the highest known 
point to which that river had been ascended. This 
is assigned about three thousand stadia (three or 
four hundred miles) beyond Meroe,* which does 
not give the fifty-two days' sail of Herodotus ; so 
that it would appear as if the Nile had been traced 
to a higher point in his time, than in that of Era- 
tosthenes. The latter, however, shews himself 
intimately acquainted with the details of its early 
Lib. vi. 33. 
f Lib. ii. p. 65. (ed. Casaubon). 
