Archimedes Texts

18
the Ancients in their Publick Buildings always
eft a great many of both the afore-mention'd
Kinds of Apertures. This appears from their
Theatres, which if we observe are extremely
full of Apertures, not only Stair-cases, but
Windows and Doors. And we ought so to
order the Proportions of these Openings, as
not to make very little ones in great Walls,
nor too large in small ones. In these Sorts of
Apertures various Designs have been com
mended; but the best Architects have never
made Use of any but Squares and strait Lines.
However all have agreed in this, that let them
be of what Shape they will, they should be ac
modated to the Bigness and Form of the

Building. *The Doors, then they
fay should always be more high than
broad; and the highest be such as
are capable of receiving two Circles [A] one
upon t'other, and the lowest should be of
the Heighth of the Diagonal of a Square [B]
whereof the Groundsell is one of the Sides. It
is also convenient to place the Doors in such a
Manner, that they may lead to as many Parts
of the Edifice as possible: And in order to give
Beauty to such Apertures, Care must be taken
that those of like Dimensions correspond with
each other both on the Right and Left. It was
usual to leave the Windows and Doors in odd
Numbers, but so as for the Side ones to answer
each other, and that in the Middle to be
somewhat larger than the rest. And particular
Regard was always had to the Strength of the
Building, for which Reason they contrived to
set the Openings clear from the Corners and
from the Columns, in the weakest Parts of the
Wall, but not so weak as to be insufficient to
support the Weight: It being their Custom
to raise as many Parts of the Wall as they
could plum, and as it were of one Piece
without any Interruption from the Foundation
quite up to the Covering. There is a certain
Kind of an Aperture, which in Form and
Position imitates the Doors and Windows, but
which does not penetrate the whole Thickness
of the Wall, and so, as Niches leave very
handsome and convenient Seats for Statues and
Paintings. But in what Parts these are to be
left, as also how frequent and large, will be
shewn more distinctly when we come to treat
of the Ornaments of Edifices. We shall only
observe here, that they not only add to the
Beauty of the Work, but also save some Ex
pence, as they make less Stone and Lime to
serve for the Walling. This chiefly is to be
taken Care of, that you make these Niches in
convenient Numbers, not too big, and of a just
Form; and so as in their Order to imitate the
Windows. And let them be as you will, I
have remark'd in the Structures of the Ancients,
that they never used to suffer them to take up
above the seventh Part of the Front, nor less
than the ninth. The Spaces between the
Columns are to be reckoned among the princi
pal Apertures, and are to be lest variously ac
cording to the Variety of Buildings. But we
shall speak of these more clearly in their
proper Place, and chiesly when we treat of
Sacred Edifies. Let it be sufficient to premise
here, that those Openings should be left in such
a Manner, as to have particular Respect to the
Nature of the Columns, which are design'd
for the Support of the Covering; and first, that
those Columns be not too small, nor stand too
thin, so as not to be duly able to bear the
Weight, nor too big, or set so thick as not to
leave open convenient Spaces for Passage.
Lastly, the Apertures must be different, when
the Columns are frequent from what they are
when they stand thin, because over frequent
Columns we lay an Architrave, and over the
others we turn an Arch. But in all Openings
over which we make Arches, we should con
trive to have the Arch never less than a half
Circle, with an Addition of the seventh Part
of half its Diameter: The most experienced
Workmen having found that Arch to be by
much the best adapted for enduring in a
Manner to Perpetuity; all other Arches being
thought less strong for supporting the Weight,
and more liable to ruin. It is moreover imagi
ned, that the half Circle is the only Arch
which has no Occasion either for Chain or any
other Fortification; and all others, if you
don't either chain them or place some Weight
against them for a Counterpoise, are found by
their own Weight to burst out and fall to ruin.
I will not omit here what I have taken Notice
of among the Ancients, a Contrivance certainly
very excellent and Praise-worthy: Their best
Architects placed these Apertures and the
Arches of the Roofs of their Temples in such
a Manner, that even tho' you took away every
Column from under them, yet they would
still stand firm and not fall down, the Arches
on which the Roof was placed being drawn
quite down to the Foundation with wonderful
Art, known but to few: So that the Work
upheld itself by being only set upon Arches; for
those Arches having the solid Earth for their
Chain, no Wonder they stood firm without any
other Support.