Archimedes Texts

16
and in short the whole Structure falls to Ruin.
The very Foundations themselves, which you
will hardly bèlieve, are secured by the Pro
tection of the Covering: nor have so many
Buildings been destroyed by Fire, Sword, War,
by Multitude of Enemies, and all other Ca
lamities put together, as have gone to Ruin
by being left naked and uncovered thro Negli
gence. It is certain the Coverings are the de
fensive Arms of the Building against the
Assaults and Violence of Storms and Tempests.
Wherefore our Ancestors in this as in other
things acted very laudably, in ascribing so
much Honour to the Covering, that they
spent their whole Art and Study in adorning
and beautifying it. For some of their Cover
ings we see of Brass, others of Glass, some of
Gold with gilded Beams and Rafters, and
richly adorned with Cornishes of Flowers and
Statues. Of Coverings some are open to the
Air, others not: the open are those which are
not for walking upon, but only for receiving
the Rain. Those not open to the Air, are
the Roofs and Coves that are between the
Covering and the Foundations, so that one
House seems to stand upon another. By this
means it comes to pass that the same Work,
which is the Covering to the Apartments
below, is the Aréa to those above. Of these
Coverings those above our Heads we call Roofs,
or Cielings; and those which we tread upon
with our Feet, Areas. Whether the uppermoft
Covering, which lies to the open Air, is to be
reckoned as an Area or Pavement, we shall
examine in another Place. But the Covering
to the open Air, tho' it be of a plain Super
ficies, ought never to lie even with respect to
the Area which it covers below; but shou'd
always incline of one Side to throw off the
Rain. But the Coverings within, that are of
a plain Superficies, should be in all Parts
equally distant from the Floor. All Coverings
must answer in Lines and Angles to the Form
and Shape of the Platform and Wall which
they are to cover: And as those are various,
some being all of curve Lines, others all of
strait, and others of both mixed together, the
Coverings too are therefore various, and of
several kinds. But tho' they have this natural
Difference, and that some are hemispherical;
others made up of four Arches; others vaulted;
others consisting of Parts of several Arches;
some sloping or ridged like ordinary mean
Houses: yet which-soever of these Kinds we
chuse it is absolutely necessary, that all Cover
ings shou'd be so disposed as to shelter and
shade the Pavement, and throw off all Water
and Rain, defending the whole Edifice upon
which it is placed for a Covering. For Rain
is always prepared to do Mischief, and where
ever there is the least Crack never fails to get
in and do some Hurt or other: By its Subtility it
penetrates and makes its way by its Humidity
rots and destroys, by its Continuance loosens
and unknits all the Nerves of the Building, and
in the End ruins and lays Waste the whole
Structure to the very Foundations. And for
this Reason prudent Architects have always
taken care that the Rain should have a free
Slope to run off; and that the Water should
never be stop'd in any Place, or get into any
Part where it cou'd do Hurt. And therefore
they advised, that in Places subject to much
Snow, the Coverings should have a very steep
Slope, rising even to an acute Angle, that the
Snow might never rest and gather upon them,
but fall off easily; but in more Summerish Cli
mates (to use such an Expression) they laid
their Covering less oblique. Lastly we should
endeavour if possible, without Prejudice to the
Lights or Wall, to have the whole Structure
overlaid with one equal Covering in a manner
all of one Piece, and so far jutting out, that the
Water falling from the Gutters may not wet
or soak into the Wall: and all the Coverings
should be so disposed, where there are more than
one, that one may not spout upon the other.
The Space of Covering too that the Water is
to run over should never be too large, because
upon Rains the Water gathering in the Gut
ters in too great Abundance would wash back
again and flow into the House; which would
greatly prejudice the whole Work. Where
the Area therefore is very large, the Covering
should be divided into several Slopes, and the
Rain flow off in different Places; and this is
not only attended with Convenience, but Beauty
too. If you are obliged in any Place to have
several Coverings, let them join one to another
in such a Manner, that when you are once
under one, you may pass from that to all the
rest always under shelter.