Planetarium of Archimedes?

A fragment from a complex mechanism was discovered by chance near Olbia, Sardinia, and it soon became clear that the dented gear wheel showed similarities with the mechanism of Anticythera. This fragment, however, was made of a brass alloy unknown otherwise at the time. 

[Kircher's reconstruction of the sphere of Archimedes]

Thanks to the detailed writings of Cicero in the 1^st century BC, we know that Archimedes constructed a Planetarium (Orrery). The celestial globe is mentioned by Ovid in the 1^st century BC and by Claudian, a 4^th-century Latin poet associated with the court of Emperor Honorius in Mediolanum (Milan). 

When, in 212 BC, the Romans sacked Syracuse, Consul Marcus Claudius Marcellus brought to Rome a device that was built by the famous mathematician. It represented the motion of the Sun, Moon, and the planets reproduced on a sphere. In short, a modern Planetarium. 

It was Gaius Sulpicius Gallus, who reported the story as he had seen the object personally and knew how to operate it. Cicero was amazed that Archimedes had been able to generate the motion of the individual planets starting from a single rotation. The Planetarium was placed inside a glass sphere. This corresponds to what Archimedes wrote in a now-lost treatise On Sphere-Making detailing the construction of the Planetarium. 

Livy, who died in 17 AD, wrote that before the Battle of Pydna in 168 BC, Gallus, an astronomer himself, used the Planetarium to predict a lunar eclipse on the night before the battle. The news was shared with his Roman legionnaires to prevent them from panicking, but the Macedonians freaked out. 

A first reconstruction based on the section of the gear wheel found near Olbia revealed that it counted 55 dents in total. Noteworthy is the shape of the dents, which is not triangular as in the case of the Anticythera mechanism but slightly curved as used in our modern gear wheels. This shape proves to be more efficient and allows a higher precision. In antiquity, these wheels were created manually and the craftsmen had to do without the use of our modern measuring and cutting tools, which emerged only a few centuries ago. 

Marcus Claudius Marcellus, owner of the Planetarium, was sent off to Spain to fight the Iberic Celts in 152 BC. It is reasonable to assume that Marcellus took the Planetarium with him – a sign of his status – and that his ship was wrecked in the region of Olbia, crashing the Planetarium. 

The Planetarium has been dated between the end of the 3^rd century BC and the mid-2^nd century BC. It thus predates the Anticythera mechanism from the 1^st century BC generally ascribed to Archimedes. However, the analog computer may well have been reproduced based on Archimedes’ description.

It must have been one of the marvels from Hellenistic times, many of which still remain to be discovered!

[the section found near Olbia is thoroughly discussed in this YouTube]

More news from Anticythera

The site of Anticythera remains a treasure trove for underwater archaeologists. In September 2016, they returned to the site of the shipwreck and brought back bronze limbs, the lid of a sarcophagus, parts of different marble statues and a mysterious bronze disk.

The ship, one of the largest for its time (1^st century BC) was nearly 40 meters long and transported a rich collection of artworks that was meant to decorate the houses of wealthy Romans (see also: The treasures of Anticythera’s shipwreck).

It is so exciting to be able to share the divers’ experiences under water as they handle a lost bronze arm belonging probably to a philosopher or an intriguing bronze disk that carries the image of a bull. Let’s enjoy this little video:

Anticythera made headlines when the famous mechanism was brought to light early last century and has kept scientists and researchers busy ever since.

The most significant find of this season may well be the human remains. This is a great opportunity to examine this skeleton’s DNA, hoping that the bones do indeed belong to one of the seafarers who died when the ship went down and not to a later shipwreck.

The Ingenious Tower of the Winds in Athens

The Horologion of Andronikos best known as the Tower of the Winds is an octagonal tower built from Pentelic marble by the architect and astronomer Andronicus of Cyrrhus in Macedonia. It stands near the eastern Propylon on the Roman Agora and dates from Hellenistic times, probably from the 2^nd century BC (although some are inclined to date it to around 50 BC).

It is one of those buildings that proves – if proof is needed – the highly developed knowledge about wind and water in antiquity.

The Tower of the Winds has just been cleaned and restored (2016) and is truly worth the visit. The tower is 12 meters high and measures eight meters in diameter. The top of its conical roof that is still in place was topped in antiquity by a bronze weather vane like we know from our own church steeples. Each of the eight sides of the tower faces a specific wind direction that is illustrated with appropriate friezes: Boreas for the North, Kaikias for the Northeast, Eurus for the East (but according to some it is the god of the southeastern winds), Apeliotes for the Southeast (although he is the god of the rising sun and thus East), Notus for the South, Lips for the Southwest, Zephyrus for the West, and finally Skiron for the Northwest. Underneath each relief is a sundial, eight in total, making it the first clock tower in history.

Inside the tower, a mechanism powered a water clock or clepsydra driven by the water coming down from the Acropolis. The mechanism has recently been compared to that of Anticythera. It functioned thanks to water pressure created by the interior of a cylindrical space situated on the south side of the monument. The water channels are clearly visible in the tower’s pavement.

The construction has been preserved over the centuries as the tower was converted into a Byzantine church and during Ottoman rule, it was used by the whirling dervishes. It is hard to imagine that by then the tower had sunk into dust and dirt, meaning that only the upper half was still visible.

[Click here to see all the pictures of the Tower of the Winds]

The treasures of the Anticythera shipwreck

When I visited Athens’ Archaeological Museum for the first time in the 1970s, I was fascinated by a group of marble sculptures gathered in the downstairs garden. Their provenance was off the island of Anticythera, rescued by sponge divers in the early days of the 20^th century. The parts of the marble statues that sank into the sandy seabed had been well preserved, but those that had been exposed to the salty water had suffered seriously from erosion. As a result, some statues had turned into grotesque shapes that still suggested their noble origins.

Key finds, however, were a life-size bronze statue of a young hero or god, possibly from a Peloponnesian workshop made around 340-330 BC, the bronze head of a philosopher probably from a Cynic school, created in the 3^rd century BC, and an intriguing lump of bronze gearwheels known as the Mechanism of Anticythera from the 2^nd century BC. Other smaller items were evidence of daily life aboard the ship, such as cooking and storage vessels, ceramic tiles from the cabin’s roof, as well as a number of bronze coins; also, some jewelry and fine glassware were found at the site. In 1976, Cousteau also explored the sea bottom and found more objects like small bronze statues, but also bronze and silver coins, most of them minted in Pergamon.

All these objects were shipwrecked, apparently during a storm, near the island of Anticythera between 70 and 60 BC. The vessel, one of the largest of her time (twice the size of an average ship), could enter only a handful of harbors in Asia Minor, among which were Pergamon, Ephesos, Rhodes, and Delos. This led, together with the abovementioned coins, to the conclusion that the ship must have sailed from Pergamon, heading for Rome. At that time, Rome ruled over the eastern Mediterranean, and Greek art was very popular.

Yet the story behind the so-called Mechanism of Anticythera is far more complex. Altogether 82 separate fragments have been retrieved, but it is mainly the cluster of the three largest pieces that holds the story. This sophisticated machine dates from the 2^nd century BC, and initially, nobody understood what it was. A handful of reconstructions were built mostly in the second half of the 20^th century, but early research lacked the technology we have today to visualize the intrinsic elements, such as the use of digital photography, CT-scans, surface imaging called PTM, and X-rays in 2-D and 3-D.

The technical details are far beyond my capabilities and comprehension, but I find it terribly exciting that such a complex mechanism ever existed two thousand years ago. The conclusion is that the mechanism was an astronomical calendar, a computer avant-la-lettre that enabled its user to track down the cycles of our solar system.

An in-depth analysis of the dials and their dents has revealed that the mechanism is based on a 19-year calendar with 223 lunar months, including eclipse predictions. All twelve months of the year have been identified and recognized as belonging to the Corinthian calendar. This led to believe that the mechanism was either constructed in Corinth or in one of its colonies, like Syracuse, home of Archimedes. Researchers also deciphered a small dial serving to indicate the four-year cycle of the Olympic Games, the two-year cycle of the Nemean Games, as well as the Delphic and Corinthian Games. The other side of the mechanism portrays the interaction of the Sun, Moon, stars, and all five planets.

Today it is generally accepted that this is an ancient analog computer and may well have been created by nobody less than Archimedes. After the Romans conquered Sicily, the mechanism was probably taken to Pergamon and finally lost at sea during its transfer to Rome in the first century AD.

There is this most interesting documentary posted on YouTube, “Decoding the Mechanism of Anticythera” that shows a detailed approach to the entire research and its conclusions. It makes you wonder what would have happened if Archimedes had not been killed “by accident” by the invading Romans or if his heritage would have fallen into capable hands, i.e., somebody who could value – if not, understand - his inventions. It took mankind another thousand years to reinvent this machine!