6 SIEGE OF THE SOUTH POLE 
at noon, there was no such easy method of finding longi- 
tude, because there was no time-keeper by which a travel- 
ler could carry with him the time of an initial meridian. 
The instruments for finding latitude were also clumsy in 
the extreme, and the method most in use for centuries 
was that of noting the length of the longest day. It was 
difficult, for these reasons, to lay out a line due north and 
south, the ends of which could be fixed with any precision 
in order to measure the size of the Earth; hence it is 
amazing how very near the estimate of such a mathema- 
tician as Eratosthenes came to the truth. 
When the shape and size of the Earth became known 
the main problem of geography was completely altered ; 
it was no longer the question of the possibility of an 
antarctic region existing; but the possibility of reaching 
it. The problem, in fact, was the wider one of the dis- 
tribution of land and water, of climate and the means 
of travelling, the antarctic problem of to-day being but 
the unsolved residue of the larger problem. 
The estimates of Eratosthenes (about 250 B. C.) made 
it apparent that the Habitable World of the Greeks occu- 
pied only about one-quarter of the surface of the sphere. 
It seems a limited World to us, though vast enough to 
those whose swiftest means of transport were the horse 
and the galley. Controversy was active amongst the 
Greek philosophers as to the plan of the Earth. The 
Stoics upheld the continuity of the ocean and viewed the 
Habitable World as one out of four large islands placed 
symmetrically upon the sphere, one to balance the other. 
Nature loved life, so those three unknown Worlds were 
also inhabited and it was easy to fit the hypothetical peo- 
ples with appropriate and expressive names according to 
their position with regard to the Old World, the Antoken, 
