Tag: Byzantine Science

A Tabernacle-Shaped Earth

Illustration of the world in a tabernacle, from a 9th-century copy of Cosmas Indicopleustes’s “Topographia Christiana,” BAV, vat. graec. 699, fol. 43r

Although Cosmas Indicopleustes is far from a household name, he enjoys an outsized reputation (at least in the abstract) as a representative of the benighted medieval belief that the earth was flat. To be sure, in his “Topographia Christiana” he says the earth is a parallelogram surrounded by oceans. Moreover, this parallelogram-shaped earth was stuffed inside a tabernacle-shaped cosmos. He thought the cosmos must be shaped like a tabernacle because its shape had inspired Moses to construct the Biblical tabernacle. Cosmas was not, however, a geographer nor was his “Topographia Christiana” clearly meant to represent physical reality. Moreover, there’s little evidence that anybody before the late 17th or early 18th century cared about Cosmas’s ideas. This didn’t stop people like Andrew White from making up stories about Cosmas having influenced medieval ideas about the construction of the earth. Alas.[1]


  1. I’ve written about Cosmas before.  ↩

Eratosthenes Measures the Earth

An 13th/14th-century drawing of Eratosthenes’ method for calculating the circumference of the earth. The sun shown at the summer solstice shines down on Syene and Alexandria. This drawing is in “Cleomedis introductio de motu coeli et planetarum,” BSB-Hss Cod.graec.482, fol. 31r.

In this 13th/14th-century copy of Cleomedes’ textbook on astronomy, typically referred to as “De motu circulari corporum caelestium,” is this illustration of Eratosthenes’ method for calculating the circumference of the earth. The outer oval is the signs of the zodiac in their zoomorphic/anthropomorphic forms, each labeled with its name. The sun is located in Cancer, in the upper right, illustrated by a head looking down and the label “ἥλιος.” Rays of light stream down on two cities. On the right is Syene; on the left is Alexandria (labeled accordingly). The city walls of each are adorned with a sundial. The gnomon on the dial in Syene is casts no shadow, since the sun shines down directly on the city. The gnomon in Alexandria would clearly cast a shadow, since the sunlight shines on the town at an angle. Between the two towns is a distance of 5,000 stadia, as noted by the “τὸ μεταξὺ στάδια Ε.” In the bottom is an illustration showing the path of the sun.

Cleomedes was a Greek astronomer active sometime in late antiquity (scholars don’t agree on when he lived). He is known primarily for his work, On the Circular Motions of the Celestial Bodies, a kind of textbook on astronomy. He preserves previous authors’ work, especially much of Posidonius’s work. He is also the earliest source for the story illustrated here about how Eratosthenes measured the circumference of the earth.

Another Byzantine Wind Diagram

A 16th-century copy of a Byzantine wind diagram from BN Grec 2493, fol. 165v.

This Byzantine wind diagram, also titled “Diagram about thunder, storms, rainstorms, and earthquakes,” closely resembles the previous Byzantine Wind Diagram. Both come from latter 16th-century manuscripts. This particular copy was never finished—the elements are missing from the center of the diagram, the “παναχῆ” is also missing in this copy.[1] Once again, we see the aspects in the inner circle, the second square is meteorological phenomena, the 12 winds, the signs of the zodiac, south and north poles, and the captions indicating from the right and left parts of the cosmos.

As with the other codex, Royal MS 16 C XII, this codex (BN Grec 2493) contains three texts on the astrolabe—the catalog entry identifies them as Philoponus’s, an anonymous text,[2] and Gregoras’s along with scholia on that last work—and a variety of anonymous astronomical diagrams. The codex also includes texts by Theon of Alexandria.


  1. The image is b&w, so I can’t tell what color inks are used, but the division of inks between the different words also resembles that used in the other diagram. That is, the title, the caption along the perimeter, the poles, the signs of the zodiac, and the four aspects appear to be in a different (red?) ink.  ↩

  2. I suspect this is the text typically attributed to Ammonius, but I haven’t had the time to confirm that suspicion.  ↩

Byzantine Wind Diagram

A 16th-century copy of a Byzantine wind diagram from Royal MS 16 C XII, fol. 49r.

This diagram, titled “Diagram about thunder, storms, rainstorms, and earthquakes,” seems to be a type of wind diagram, which arranged the terrestrial elements, planetary aspects, meteorological phenomena, and winds, signs of the zodiac, and the cardinal directions. Starting from the center we see the four elements—earth, water, air, fire—surrounded by the common planetary aspects. The first square is labeled παναχῆ, “everywhere,” then meteorological phenomena, e.g., lightning, thunder, earthquakes, hail, storms, then the 12 winds, then the signs of the zodiac. The very top of the diagram is labeled “south pole;” the bottom is labeled “north pole.” In red across the top half (starting at the 9 o’clock position) is “From the right (δεξιων) parts of the cosmos;” across the bottom half (starting at the 3 o’clock position) is “From the left parts of the cosmos.”

These diagrams have received little attention, which has (predictably) focused on the Latin tradition.[1] Such diagrams appear regularly in Byzantine astronomical manuscripts.

This diagram is part of a collection of astronomical/cosmological diagrams in Royal MS 16 C XII, a later 16th-century manuscript first owned by Isaac Casaubon, the brilliant classical scholar and historian.[2] Other texts in the codex include the trio of texts on the astrolabe—Philoponus’, Ammonius’, and Gregoras’[3]—as well as a printed text on the astrolabe by Nikolaus Sophianos.


  1. See B. Obrist, “Wind Diagrams and Medieval Cosmology,” Speculum 72(1997): 33–84 (JSTOR’s paywall will likely exclude you, sorry).  ↩

  2. See Hos Advent Calendar 1 for another diagram from this codex.  ↩

  3. See HoS Advent Calendar 3 for another codex with that trio of texts.  ↩

Byzantine Diagram of Planetary Aspects

A manuscript table of planetary aspects in a codex of Greek mathematical works (Staatsbibliothek zu Berlin, Phill. 1553).
A manuscript table of planetary aspects in a codex of Greek mathematical works (Staatsbibliothek zu Berlin, Phill. 1553).

A sixteenth-century copy of a Byzantine diagram showing the basic astrological configurations of the planets: “Table of the whole circle of the 12 zodiac signs and how it is divided into aspects.”[1] The table gives the degrees between the planets in each aspect, the symbol used to indicate that arrangement, and the distance in signs between planets in a given aspect.

The table of planetary aspects with some basic translations.
The table of planetary aspects with some basic translations.

Imagine looking down on the circle of the zodiac, the various aspects are illustrated in the following diagram.

The basic planetary aspects illustrated on the zodiac.
The basic planetary aspects illustrated on the zodiac.

This table of planetary aspects is in ms. Phill. 1553 in the Staatsbibliothek zu Berlin. Phill. 1553 is a sixteenth-century codex that includes various Greek mathematical texts by both classical and Byzantine authors, e.g., Ptolemy’s harmonics along with a commentary, excerpts from Ptolemy’s Syntaxis, and the common trio of astrolabe texts—Philoponus’s, Ammonious’s, and Gregoras’s (as well as a scholia on the last work).


  1. More mechanically, the word σχηματισμούς translates as “configurations,” but here it means aspects, that geometric relationship that planets can have to each other.  ↩