chapter 9.2 The Antikythera Mechanism James C. Evans 1 Introduction The Antikythera Mechanism is an astronomical model and computing ma- chine that was retrieved from an ancient shipwreck in 1901. It is named for the island (between Crete and the southern end of the Peloponnesus) near which the wreck was discovered. The Mechanism survives in 5 large fragments and some 77 smaller ones at the National Archaeological Museum in Athens and is remarkable for its gears, 30 of which remain.1 Ancient texts discuss the theory and use of gears but all the devices described are quite simple [e.g., Pappus, Coll. 8; Hero, Mech.]. No one would have guessed from these texts that a machine of such complexity could have been built in the ancient world. Nearly all the surviving parts of the Mechanism are devoted to mod- eling solar and lunar phenomena. But Greek inscriptions on the Mechanism mention the planets as well as planetary phenomena (stations and greatest elongations), so it is likely that the device originally included another 20 gears or so. According to Cicero [De re pub. 1.21–22],2 Archimedes built a model that replicated the motions of the Sun, Moon, and planets and even foretold eclipses. This wonderful prize was taken back to Rome by Marcellus after his capture of Syracuse in 212 bce. Cicero tells this story in a philosophical dialogue set several generations before his own time and he never expressly says that he himself had seen Archimedes’ machine. Some scholars therefore doubt the details reported by Cicero—perhaps Cicero has supplied details from the machine built by his teacher, Posidonius, around 70 bce. In any case, ϲφαιροποιία (sphere-making)—the art of constructing models of the cos- mos ranging from globes and armillary spheres to geared mechanisms such as the Antikythera Mechanism—was a recognized branch of the mechan- ical arts.3 According to Pappus [Hultsch 1876–1878, 3.1027; Ver Eecke 1933, 1 For Fragments A and C, see Plates 1 and 2, pp. 341–342. 2 Unfortunately, the manuscript breaks off in the course of the discussion. Cicero mentions Posidonius’ recently constructed machine in De nat. deor. 2.88. 3 For an introduction to sphere-making, see Evans 2014; Evans and Berggren 2006, 43–48, 51–53. © koninklijke brill nv, leiden, 2020 | doi:10.1163/9789004400566_033 the antikythera mechanism 341 plate 1 Fragment A of the Antikythera Mechanism This fragment contains 29 of the 30 surviving gears. It is dominated by the large, four-spoke wheel, whose rotation represented the solar year. [©Hellenic Min- istry of Education and Religious Affairs, Culture and Sports/Archaeological Receipts Fund] National Archaeological Museum, Athens 2.813–814], citing Carpus of Antioch, Archimedes wrote a book on this sub- ject (now lost). In the second century ce, both Theon of Smyrna [Exp. 3.30] and Ptolemy [Hypoth. plan. 1.1: see Hamm 2011, 45] mentioned sphere-making. So, whatever one thinks of the details of Cicero’s account, it seems that the art of sphere-making was practiced at least from the late third century bce to the mid-second century ce. In Greek, an individual device such as the Antikythera Mechanism was also called a ϲφαιροποιία or sometimes simply a ϲφαῖρα (sphere). The Antikythera Mechanism was about the size of a large shoe box. The enclosure was made of wood and the front and back faces, as well as the work- ing parts, were of bronze. Two doors or covers could be closed to protect the Mechanism when it was not in use. The blank space on the interiors of the doors, as well as on the front and back faces of the Mechanism, was covered with inscriptions describing the features of the device..