nt books, in
the first seven treating of buildings and in the eighth of water. In
this I shall set forth the rules for dialling, showing how they are
found through the shadows cast by the gnomon from the sun's rays in the
firmament, and on what principles these shadows lengthen and shorten.

CHAPTER I

THE ZODIAC AND THE PLANETS

1. It is due to the divine intelligence and is a very great wonder to
all who reflect upon it, that the shadow of a gnomon at the equinox is
of one length in Athens, of another in Alexandria, of another in Rome,
and not the same at Piacenza, or at other places in the world. Hence
drawings for dials are very different from one another, corresponding to
differences of situation. This is because the length of the shadow at
the equinox is used in constructing the figure of the analemma, in
accordance with which the hours are marked to conform to the situation
and the shadow of the gnomon. The analemma is a basis for calculation
deduced from the course of the sun, and found by observation of the
shadow as it increases until the winter solstice. By means of this,
through architectural principles and the employment of the compasses, we
find out the operation of the sun in the universe.

2. The word "universe" means the general assemblage of all nature, and
it also means the heaven that is made up of the constellations and the
courses of the stars. The heaven revolves steadily round earth and sea
on the pivots at the ends of its axis. The architect at these points was
the power of Nature, and she put the pivots there, to be, as it were,
centres, one of them above the earth and sea at the very top of the
firmament and even beyond the stars composing the Great Bear, the other
on the opposite side under the earth in the regions of the south. Round
these pivots (termed in Greek [Greek: poloi]) as centres, like those of
a turning lathe, she formed the circles in which the heaven passes on
its everlasting way. In the midst thereof, the earth and sea naturally
occupy the central point.

3. It follows from this natural arrangement that the central point in
the north is high above the earth, while on the south, the region
below, it is beneath the earth and consequently hidden by it.
Furthermore, across the middle, and obliquely inclined to the south,
there is a broad circular belt composed of the twelve signs, whose
stars, arranged in twelve equivalent divisions, represent each a shape
which natur