Ethiopia, before
it enters Egypt, passes by the cataracts. Then growing on a sudden,
contrary to its nature, raging and violent in those places where it is
pent up and restrained; after having, at last, broken through all
obstacles in its way, it precipitates itself from the top of some rocks to
the bottom, with so loud a noise, that it is heard three leagues off.

The inhabitants of the country, accustomed by long practice to this sport,
exhibit here a spectacle to travellers that is more terrifying than
diverting. Two of them go into a little boat; the one to guide it, the
other to throw out the water. After having long sustained the violence of
the raging waves, by managing their little boat very dexterously, they
suffer themselves to be carried away with the impetuous torrent as swift
as an arrow. The affrighted spectator imagines they are going to be
swallowed up in the precipice down which they fall; when the Nile,
restored to its natural course, discovers them again, at a considerable
distance, on its smooth and calm waters. This is Seneca's account, which
is confirmed by our modern travellers.

3. _Causes of the Inundations of the Nile._--The ancients have invented
many subtle reasons for the Nile's great increase, as may be seen in
Herodotus, Diodorus Siculus, and Seneca.(287) But it is now no longer a
matter of dispute, it being almost universally allowed, that the
inundations of the Nile are owing to the great rains which fall in
Ethiopia, from whence this river flows. These rains swell it to such a
degree, that Ethiopia first, and then Egypt, are overflowed; and that
which at first was but a large river, rises like a sea, and overspreads
the whole country.

Strabo observes,(288) that the ancients only guessed that the inundations
of the Nile were owing to the rains which fall in great abundance in
Ethiopia; but adds, that several travellers have since been eye-witnesses
of it; Ptolemy Philadelphus, who was very curious in all things relating
to arts and sciences, having sent thither able persons, purposely to
examine this matter, and to ascertain the cause of so uncommon and
remarkable an effect.

4. _The Time and Continuance of the Inundations._--Herodotus, and after him
Diodorus Siculus, and several other authors, declare, that the Nile begins
to swell in Egypt at the summer solstice, that is, about the end of June,
and continues to rise till the end of September; and then decreases
gradually during t