IV.] INUNDATION OF THE NILE. 63
historian does not name its author, is unquestionably that of
Hecataeus—though more than half a century kter in date than
the preceding, is far more primitive in its character. According
to this, the increase of the volume of water was due to the
connexion of the Nile with the circumfluent river Oceanus, from
which in the southern part of its course it was supposed to be
derived; and the sweetness of its water was accounted for by the
supposition that its saline ingredients evaporated owing to the
heat of the sun in its passage through the torrid regions1.
Herodotus rightly dismisses this explanation without further dis-
cussion, as depending on an antiquated theory.
He treats with hardly greater consideration the naxasoras»
third view, which is assigned by Diodorus and others to Anax-
agoras, that it proceeded from the melting of snow during the
summer on the mountains in the interior of Libya. Notwith-
standing the reasonableness of this as a conjecture, the historian
at once dismisses it, on the ground, which we now know to be
erroneous, that it was impossible for snow to lie in so hot a
country. After disproving these views to his satis-
faction he propounds his own, which has very
little to recommend it; namely, that, as in the winter-time the
sun withdraws towards the upper parts of Libya, the streams
which feed the rivers there will naturally shrink during that
season, in consequence of the scorching heat of his rays. This
suggestion might serve as a possible explanation of the lowering
of the level of the water in winter, but leaves untouched the
question of its overflow in summer. It was reserved
for Aristotle and Eratosthenes to suggest the true
cause, in the tropical rains which fall during the
spring and early summer on the highlands about the upper
waters of the Blue and White Nile; and this was afterwards
confirmed by Agatharchides through information obtained from
natives of the interior of Africa.
We must here notice two inventions, generally attributed by
1 See Diodor. i. 40. 4; fiaprvpeiv ferofrrois Kdlrfyv forepjSoX?^ -rijs yKvidnp-as
roO /earA rbv NrfXo? Waros* && -yip TJJS KaraKCKavfj^y^ aMv jMovra /rafltyw&u,
xai 8& roOro yXwcfrrarov efrat vtorw T&V yrvrafuw, are ffoei roO rvpdfavs v&