Tag: Byzantine Science

Apollodorus’s Siege Tower

An illustration from a Byzantine copy of Apollodorus of Damascus’s “Πολιορκητικά” showing a siege tower with an assault bridge for scaling walls. This drawing is from BNF suppl. gr. 607, fol. 38r, a manuscript dated sometime between the 11th and 14th centuries.

Apollodorus of Damascus is generally thought to have written the “Πολιορκητικά,” a treatise on siege engines, addressed to an unnamed emperor (probably Trajan). The text first treats siege engines used to besiege a hilltop fort, machines to protect troops from objects rolled down the hill as well as devices for protecting men attacking the base of the walls. It describes devices for drilling through walls and setting fire to walls as well as sheds for battering rams. The text also describes towers used to scale walls and invade a fort as well as towers with pivoting arms to sweep defenders off the walls.

This image of a siege tower with bridge is a common illustration in Apollodorus manuscripts, as seen in this 15th-century copy of Apollodorus’s “Πολιορκητικά” in Oxford, Magdalen College, fonds principal gr. 14, fol. 37v

Apollodorus worked on various engineering and building projects for the emperor Trajan in the early second century CE. He was responsible for such projects as Trajan’s Bridge over the Danube during the campaign in Dacia, Trajan’s Column and Trajan’s Forum, various triumphal arches, baths, and other smaller building projects.[1] During Emperor Hadrian’s reign, he was banished and then executed around 130 CE.


  1. He is sometimes given credit for redesigning the imperial residence as well as the Pantheon, but clear evidence is lacking. For a nice post on Apollodorus’s works, see Apollodorus of Damascus: Architect of Empire.  ↩

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.  ↩