Archimedes Texts

234
pened at Philippi, where, as we are informed
by Theophrastus, upon drawing off the Water
and drying up a Lake, the Country was made
warmer. The Cause of these Alterations is
supposed to have lain in the Purity or Gross
ness of the Air; for a thick Air is more dif
ficultly moved, and longer retains either the
Heat or the Cold than a thin one, which is
soon apt to be frozen with Cold, or on a Change
of Weather, to be warmed again with the Sun's
Heat. A Country which lies uncultivated and
neglected is said to afford a thick and unhealthy
Air; and in Places so much covered with
Wood, that neither Sun nor Wind can easily
get through, the Air is generally crude. The
Caves about the Lake Avernus were so sur
rounded with thick Woods that the Sulphur
which exhaled from them used to kill the Birds
which flew over them: But Cæsar, by cutting
down those Woods, made that pestilential Spot
of Ground very healthy. At Leghorn a Sea-port
Town in Tuscany, the Inhabitants used always
to be afflicted with severe Fevers in the Dog
days: By banking off the Sea with a
good Wall, the Town was freed from those
Distempers; but afterwards, when they let the
Water again into their Ditches, for the better
Fortification of the Place, their Fevers return'd.
Varro writes, that when his Camp lay in the
Island of Coroyra (now Corfu) and his Soldiers
died apace of Pestilence; by keeping all the
Windows towards the South close shut, he
preserved his Army. At Murano, a famous
Town belonging to the Venetians, they are
very seldom touched with the Plague, though,
their neighbouring Metropolis, Venice, is sre
quently and severely afflicted with it. The
Reason of this is supposed to be the great
Number of Glass-houses there; for it is very
certain that the Air is wonderfully purged by
Fire. And for a Proof that all Manner of
Poisons hate the Fire, it is observed, that the
dead Bodies of poisonous Animals do not breed
Worms, like others; because it is the Nature
of Poison to destroy and totally to extinguish
the Principles of Life: But if such Bodies are
touched by Lightening they will engender
Worms, because then their Poison is destroyed
by Fire; for Worms are bred in the dead Bo
dies of Animals from no other Cause than a
certain fiery Power in Nature working upon a
Humidity which is apt to be put in Motion by
a Heat which it is the Property of Poison to
extinguish, where it prevails, as it is itself ex
tinguished by it, where that Heat is the most
powerful. If you root out poisonous Herbs,
and especially Squills, the good Plants will
draw to themselves the bad Nourishment which
they used to imbibe from the Earth, by which
means our Food will be corrupted. It may be
of Service to shelter your House from unwhole
some Winds by a Grove and especially of Ap
ple-trees; for it is of a good deal of Conse
quence out of the Shade of what Leaves you
receive you Air. Pitch-trees are faid to be
very good for Phthysical Folks, or for those
who are recovering their Health slowly after
long Sickness. It is contrary with Trees which
have a bitter Leaf, for they yield an unwhole
some Air. Thus where-ever the Country is
low, close and mashy, it will be of Service to
lay it quite open to the Sun and Air; because
the Damps and noxious Animals which arise
from such Places will be presently destroyed
by Dryness and Winds. At Alexandria is a
publick Place to which the Filth and Rubbish
of the Town is carried, and it is now grown
up to such a Hill, that it serves as a Land-mark
to Mariners to find their Way into the Port.
How much more convenient would it not be
to fill up low hollow Places with such Stuff?
Thus at Venice, (for which I highly applaud
them) they have in my Time filled up several
of their Marshes with the Rubbish of the Town.
Herodotus tells us, that the People who live a
mong the Marshes in Ægypt, in order to avoid
the Gnats, lie a Nights in very high Towers.
At Ferrara by the Po few or no Gnats appear
within the City; but out of Town, to those
who are not used to them, they are execrable.
It is supposed that they are driven from the
Town by the great Quantity of Smoke and
Fire. Flies do not haunt Places which are
cold or exposed to much Wind, and especial
ly where the Windows are very high. Some
say that Flies will not enter where the Tail of
a Wolf is buried, and that a Squill hung up
will also drive away venomous Animals. The
Ancients made use of a great many Defences
against the violent Heats; among which I am
very well pleased with their Crypts or subter
raneous Porticoes, Vaults, which received Light
no where but from the Top. They were also
fond of Halls with large Windows turned away
from the South, open to a cool Air, and shad
ed by some neighbouring Edifice. Metellus,
the Son of Octavia, Augustus's Sister, made an
Awning over the Forum with Sails, that
the People might follow their Causes without
prejudicing their Healths. But Air is more