Alberti, Leone Battista, Architecture, 1755

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1muſt never be leſs than four Foot; if fifty Cu­
bits, five Foot; if ſixty Cubits, ſix Foot, and
ſo on in the ſame Proportion.
Theſe Rules
relate to Towers that are plain and ſimple:
But ſome Architects, about half Way of the
Height of the Tower, have adorned it with a
Kind of Portico with inſulate Columns, others
have made theſe Porticoes ſpiral all the Way
up, others have ſurrounded it with ſeveral Por­
ticoes like ſo many Coronets, and ſome have
covered the whole Tower with Figures of Ani­
mals.
The Rules for theſe Colonades are not
different from thoſe for publick Edifices; only
that we may be allowed to be rather more
ſlender in all the Members, upon Account of
the Weight of the Building.
But whoever
would erect a Tower beſt fitted for reſiſting
the Injuries of Age, and at the ſame Time ex­
tremely delightful to behold, let him upon a
ſquare Baſis, raiſe a round Superſtructure, and
over that another ſquare one, and ſo on, ma­
king the Work leſs and leſs by Degrees, ac­
cording to the Proportions obſerved in Co­
lumns.
I will here deſcribe one which I think
well worthy Imitation.
Firſt from a ſquare
Platſorm riſes a Baſement in Height one tenth
Part of the whole Structure, and in Breadth
one fourth Part of that whole Height.
Againſt
this Baſement, in the Middle of each Front
ſtand two Columns, and one at each Angle,
diſtinguiſhed by their ſeveral Ornaments, in the
ſame Manner as we juſt now appointed for Se­
pulchres.
Over this Baſement we raiſe a ſquare
Superſtructure like a little Chapel, in Breadth
twice the Height of the Baſement, and as high
as broad, againſt which, we may ſet three,
four or five Orders of Columns, in the ſame
Manner as in Temples.
Over this, we make
our Rotondas, which may even be three in
Number, and which from the Similitude of
the ſeveral Shoots in a Cane or Ruſh, we ſhall
call the Joints.
The Height of each of theſe
Joints ſhall be equal to its Breadth, with the
Addition of one twelfth Part of that Breadth,
which twelfth Part ſhall ſerve as a Baſement
to each Joint.
The Breadth ſhall be taken
from that ſquare Chapel which we placed up­
on the firſt Baſement, in the following Man­
ner: Dividing the Front of that ſquare Chapel
into twelve Parts, give eleven of thoſe Parts to
the firſt Joint; then dividing the Diameter of
this firſt Joint into twelve Parts, give eleven of
them to the ſecond Joint, and ſo make the
third Joint a twelfth Part narrower than the
ſecond, and thus the ſeveral Joints will have
the Beauty which the beſt ancient Architects
highly commended in Columns, namely, that
the lower Part of the Shaft ſhould be one ſourth
Part thicker than the upper.
Round theſe
Joints we muſt raiſe Columns with their proper
Ornaments, in Number not leſs than eight, nor
more than ſix: Moreover, in each Joint, as al­
ſo in the ſquare Chapel, we muſt open Lights
in convenient Places, and Niches with the Or­
naments ſuitable to them.
The Lights muſt
not take up above half the Aperture between
Column and Column.
The ſixth Story in this
Tower, which riſes from the third Rotonda
muſt be a ſquare Structure, and its Breadth and
Height muſt not be allowed above two third
Parts of that third Rotonda.
Its Ornament
muſt be only ſquare Pilaſters ſet againſt the
Wall, with Arches turned over them, with
their proper Dreſs of Capitals, Architraves and
the like, and between Pilaſter and Pilaſter, half
the Break may be leſt open for Paſſage.
The
ſeventh and laſt Story ſhall be a circular Por­
tico of inſulate Columns, open for Paſſage
every Way; the Length of theſe Columns, with
their Intablature, ſhall be equal to the Diame­
ter of this Portico itſelf, and that Diameter
ſhall be three fourths of the ſquare Building,
on which it ſtands.
This circular Portico ſhall
be covered with a Cupola.
Upon the Angles
of the ſquare Stories in theſe Towers we ſhould
ſet Acroteria equal in Height to the Archi­
trave, Freze and Cornice which are beneath
them.
In the lowermoſt ſquare Story, placed
juſt above the Baſement, the open Area within
may be five eighths of the outward Breadth.
Among the ancient Works of this Nature, I
am extremely well pleaſed with Ptolomey's
Tower in the Iſland of Pharos, on the Top of
which, for the Direction of Mariners, he placed
large Fires, which were hung in a continual
Vibration, and kept always moving about from
Place to Place, leſt at a Diſtance thoſe Fires
ſhould be miſtaken for Stars; to which he ad­
ded moveable Images, to ſhew from what Cor­
ner the Wind blew with others, to ſhew in
what Part of the Heavens the Sun was at that
Time, and the Hour of the Day: Inventions
extremely proper in ſuch a Structure.

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