Travellers
relating that these Countries are more infested with it than most other
Parts of _Africa_.

_GRAND CAIRO_ is crouded with vast Numbers of Inhabitants, who for the
most part live very poorly, and nastily; the Streets are very narrow,
and close: it is situate in a sandy Plain at the Foot of a Mountain,
which by keeping off the Winds, that would refresh the Air, makes the
_Heats_ very stifling. Through the midst of it passes a great _Canal_,
which is filled with Water at the overflowing of the _Nile_; and after
the River is decreased, is gradually dried up: Into this the People
throw all manner of Filth, Carrion, _&c._ so that the Stench which
arises from this, and the Mud together, is insufferably offensive[42].
In this Posture of things, the _Plague_ every Year constantly preys
upon the Inhabitants; and is only stopt, when the _Nile_, by
overflowing, washes away this Load of Filth; the _Cold Winds_, which set
in at the same time, lending their Assistance, by purifying the Air.

IN _AEthiopia_ those prodigious Swarms of _Locusts_, which at some times
cause a Famine, by devouring the Fruits of the Earth, unless they happen
to be carried by the Winds clear off into the Sea, are observed to
entail a new Mischief upon the Country, when they die and rot, by
raising a _Pestilence_[43]; the Putrefaction being hightened by the
excessive _Intemperance of the Climate_, which is so very great in this
Country, that it is infested with violent _Rains_ at one Season of the
Year, for three or four Months together[44]. And it is particularly
observed of this Country, that the _Plague_ usually invades it, whenever
Rains fall during the sultry Heats of _July_ and _August_[45], that is,
as _Lucretius_ expresses it, when the Earth is

_Intempestivis pluviisque et solibus icta_[46].

NOW if we compare this last Remark of the _Intemperance of the Climate_
in _AEthiopia_, with what the _Arabian_ Physicians[47], who lived near
these Countries, declare, that _Pestilences_ are brought by
_unseasonable_ Moistures, Heats, and want of Winds; I believe we shall
be fully instructed in the usual Cause of this Disease. Which from all
these Observations compared together, I conclude to arise from the
_Putrefaction_ so constantly generated in these Countries, when _that_
is hightened and increased by the ill State of Air now described; and
especially from the _Putrefaction_ of animal Substances.

IT is very plain, that animal Bodies a