Archimedes Texts

233
unload the Barge, which by that Means rising
higher in the Water, will pull up what is tyed
to it. It will be a Help to the Operation, if
you keep the Vessel stirring about by moving
the Rudder backwards and forwards while you
are unloading it; to shew the Use of which,
I shall just mention, that in the Country of
Præneste I have seen a moist Sort of Clay into
which if you run a Stick or a Sword but the
Depth of a single Cubit, it was not by the
Force of a Man's Arm to be got out again by
pulling; but if as you pulled you wriggled
your Arm backwards and forwards as Men do
that are turning a Skrew, it would easily come
forth. At Genoa there was a Rock lying un
der the Surface of the Water so as to stop up
the Entrance into the Port. A Man was found
in our Age, endued with surprizing Qualifica
tions both of Art and Nature, who broke it
away, and laid the Passage very wide. It is
said, that this Man used to stay under Water
many Hours together, without ever coming
up to take Breath. You may take up the Mud
from the Bottom by means of an Oyster-net
covered with Tarpawlins; for as you draw it
along it will fill itself. You may also fetch it
up from the Bottom, where the Sea is shallow,
with the following Contrivance. You must
have two Smacks, like those of Fishermen; in
the Stern of one of these you must have an
Axis upon which a very long Pole must swing
like the Beam of a Balance; to that End of
the Pole which lies out from the Stern must
be fasten'd a Shovel three Foot broad and six
long. By lowering down this Shovel to the
Bottom you scoop up the Mud, and so throw
it into the other Smack which lies by for that
Purpose. From these Principles many other
Engines yet more useful may be contrived;
but to speak of them here would be too tedi
ous. And thus much may suffice for cleaning
any Channel. The Locks in a River are made
either by Sluices or Flood-gates. For either of
these the Sides must be made full as strong as
the Piers of a Bridge. We may draw up the
heaviest Sluice without Danger to our Men, by
applying to the Spindle or Windless which is
to draw up the Sluice Wheels notch'd with
Teeth like the Wheels in a Clock, which must
take hold of the Teeth of the other Spindle
which is to be put in Motion by them. But
the most convenient of all is the Flood-gate,
which in the Middle has a Spindle that turns
upon a perpendicular Axis; to this Spindle is
fastened a broad square Valve, like the square
Sail of a Barge which may be easily turned
about to which Side of the Vessel the Master
pleases; but the two Sides of this Valve shall
not be exactly equal to one another in Breadth,
but let one be above three Inches narrower
than the other; by which means it may be
opened by a Child, and will shut again of
itself; because the Weight of the broader Side
will exceed that of the Narrower. To
each Lock you ought to make two Stops,
cutting the River in two Places, and leaving
a Space between them equal to the Length of
a Vessel, to the Intent, that if the Vessel is to
ascend, when it comes to the Stop the lower
Sluice may be shut the upper one opened; or
if it be to descend, the upper one may be shut
and the lower opened; for by this means the
Vessel will run down with the lower Part of
the Stream, while the rest of the Water is
stopp'd by the upper Sluice. There is one
Thing which I must not omit concerning
publick Ways, that I may have no Occasion
for Repetition; namely, that the Streets of a
Town ought never to be heaped up with any
Sort of Rubbish, as it is grown a bad Custom
to do under the Notion of mending them,
which should rather be done by removing and
carrying away all the Superfluities; lest the
Houses come in Time to be buried, and the
Level of the Town to be sunk under Rub
bish.

I shall now proceed to the Remedies for some
other Inconveniencies of smaller Moment;
in which I shall be as brief as possible. In
some Places, upon bringing Water to them,
the Country has been made warmer; in others,
colder. Near Larissa in Thessaly there was a
Field covered with a standing Water, which
made the Air heavy and hot. Upon carrying
off this Water, and laying the Field dry, the
Country became cooler. The contrary hap