Archimedes Texts

223
have begun concerning Water only for Drink
ing, and proceed afterwards to Canals for Na
vigation. Canals are either worked up with
Masonry, or else are only Trenches dug. Tren
ches are of two Sorts, cut either through an
open Country, or through the Bowels of a Hill,
which is called a Mine or subterraneous Con
duit. In both these, when you meet with either
Stone, Chalk, or compact Earth that does not
imbibe the Water, you will have no Occasion
for Masonry; but where the Bottom or Sides of
the Canal are not sound, then you must fortify
them. If you are obliged to carry your Canal
through the Heart of a Hill, you must observe
the Rules above laid down. In subterraneous
Conduits, at the Distance of every hundred
Foot, you should open Ventiges like Wells for
tified according as the Nature of the Earth
through which you dig requires. I have seen
such Ventiges in the Country of the Marsi near
Rome, where the Water falls into the ancient
Lake Fucinus (now called the Pie di Luco)
built very finely with burnt Brick, and of an
incredible Depth. 'Till the four hundred and
forty-first year after the building of the City,
there was no such thing as an Aqueduct built
at Rome; but afterwards those Works were
brought to such a Pitch, that whole Rivers
were conveyed to it through the Air, and we
are told, that there were so many of them, that
every single House was abundantly supplied
with Water. At first they began with subter
raneous Conduits; which indeed had a great
many Conveniencies. This hidden Work was
less subject to Injuries and being exposed neither
to the Severity of Frosts, nor to the scorching
Dog-day Sun brought the Water fresher and
cooler, nor could easily be destroyed or turned
away by Enemies that might happen to make
Inroads into the Country. These Works were
afterwards brought to such a Magnificence,
that in order to have high Jets of Water in their
Gardens and in their Bathes, they built vault
ed Aqueducts, in some Places above an hundred
and twenty Foot high, and carried on for above
threescore Miles together. From these too they
reaped Conveniencies. In several Places, and
particularly beyond the Tyber, the Water of
these Aqueducts served to grind their Corn,
and upon their being destroyed by the Enemy,
they were forced to make Mills for that Pur
pose in Ships. To this add, that by means of
this Plenty of Water the City was kept cleaner
and the Air made fresher and more wholesome.
The Architects also added some ingenious In
ventions to shew the Hours of the Day to the
great Recreation of the Beholders, by the Con
trivance of some little moving Statues of Brass,
placed in the Front of the Head of the Aque
duct, which represented the publick Games and
the Ceremony of the Triumph. At the same
Time, the Sound of musical Instruments and
sweet Voices was heard, which were caused by
the Motion of the Water. These Aqueducts
were covered in with an Arch of a good Thick
ness, to prevent the Water from being heated
by the Sun; and this Vault was plaistered on
the Inside with such a Composition as we have
formerly in this Book recommended for Floors,
to the Thickness of at least six Inches. The
Parts of the ancient Aqueduct were these.
Joining to the Incile was the Septum; along
the Course of the Conduit were the Castella;
where any higher Ground interfered the Specus
was dug; lastly, to the Head was annexed the
Calix. An ancient Lawyer gives us the fol
lowing Description of these several Parts. An
Aqueduct is a Conduit for conveying Water to
a certain Place by means of a gentle Slope.
The Septum is a Flood-gate or Water-stop
made at the Sluice for letting the Water into
the Aqueduct. The Castella are Water-houses
or Conduit-heads for the Reception of the
publick Water. The Specus is a Kind of Mill
dam dug in the Earth. The Calix is the End
or Mouth of the Aqueduct, which discharges
the Water. All these must be made of very
stout Work, the Bottom as strong as possible,
the Plaistering tight and by no means subject
to crack. The Mouth of the Sluice must be
stopt with a Flood-gate, with which you may
shut out the Water when it happens to be tur
bid, and by means whereof you may have an
Opportunity to mend any Part of the Aque
duct which is decayed, without being prevent
ed by the Water; and this Flood-gate must
have a Grate of Brass to it, that Water may
flow into the Aqueduct clearer and more re
fined, leaving behind it the Leaves, Boughs
and other Trash that fall into it. At every
hundred Cubits must be either a Conduit-head,
or a Mill-dam twenty Foot broad, thirty long,
and fifteen deep below the Bottom of the Chan
nel; and these are made to the Intent that
those Waters which either fall into the Aque
duct from the Earth, or are thrown into it too
violently, may have a Place to subside below
the other Stream, which by that means will
have room to flow on more refined and clear.
The Mouth of the Aqueduct for discharging