The cave of the Nymphs: Odyssey 13.96–112

The Phaiakes deliver Odysseus to his home island, Ithake, leaving him asleep on the shore. When he wakes up, he hides their gifts to him in a nearby cave:

At the head of the harbour is a long-leafed olive tree;
and near it, a cave, lovely and shaded,
sacred to Nymphs, who are called Naiads.
In it there are jars and amphoras
of stone; and bees store honey in them.
And there are stone looms, long, where Nymphs
weave cloths of shimmering sea-dye, a wonder to see;
and ever-flowing waters. And there are two entrances.
The one to the north is where humans gain access,
the one to the south is more divine: not that way
do men enter — that is the path for immortals.

The Neoplatonist philosopher Porphyry famously wrote an essay on this passage, interpreting it in allegorical terms (Lamberton 1983). There’s no good reason to think it’s a real cave: even Porphyry reports that no ancient geographical writer could identify it. And the Odyssey’s sense of geography is unrealistic at the best of times.

Real caves

That hasn’t stopped the modern trend for identifying real places as the setting for scenes in the Odyssey. Fans have identified the cave of the Nymphs with multiple real caves: Loizos’ Cave, at Polis Beach; Marmarospilia (‘marble cave’), near Vathi; and Lake Melissani on Kefalonia.

Ancient people left religious votive offerings in these caves, dedicated to a range of divinities, and in a few late cases they seem to have done so under the influence of the Odyssey. But that was centuries later. It doesn’t mean the Odyssey itself is thinking of realist landscapes: as we saw in looking at the wanderings, the Odyssey’s idea of prehistory is related to reality, but it’s a fictional alternate prehistoric reality.

Still, here are a few more details on these candidates.

Polis Beach, Ithaki. Until 1953 Loizos’ Cave was on the north side of the bay, at top. (Image source: DiscoverGreece.com)

Loizos’ Cave was destroyed by the 1953 earthquake, but in the 1930s it had been surveyed by the British School at Athens. This cave did have older votive offerings, some Iron Age, and a few from the Bronze Age. Where it’s possible to identify the divinities that votive offerings are dedicated to, they’re mostly Olympian gods, especially Hera and Artemis. Finds relating to nymphs or Odysseus are late: there are some Hellenistic-era nymph reliefs; and, among a hundred-odd clay masks found in the cave, there’s one mask of a female face, dating to the 2nd/1st century BCE, with ‘prayer to Odysseus’ written on the back. These don’t suggest the Odyssey had this cave in mind in the 7th century BCE: they suggest people in the Roman era were influenced by Homer. The main attraction of this cave as a candidate actually lies in twelve 9th century BCE bronze cauldrons, though they aren’t specific to any divinity, and the context suggests that if they were dedicated to a specific divinity it would most likely be Hera. See further Antonaccio 1995: 152–155. Note that some finds were apparently stolen by Schliemann, who visited the cave in the 1860s, and are presumably lost forever.

Marmarospilia near Vathi, Ithaki, photographed by Teun de Visser, July 2026. (Image source: Google Maps)

Marmarospilia (‘marble cave’) is signposted locally as ‘Cave of Nymphs’ (Σπήλαιο Νυμφών), with UNESCO endorsement — in spite of the fact that it’s 190 metres above sea level, more than a kilometre from the head of the bay where Vathi is located, and the entrance faces away from the bay. It is widely claimed — falsely — that there used to be a second entrance downhill by the bay: that’s wishful thinking, trying to make it sound more like the cave in Odyssey 13. In reality the cave extends about 25 m into the hillside, sloping upwards to the east. The identification with the Odyssey’s cave was proposed by Anna Petroheilou in 1971. The cave is normally closed because of damage done by archaeological excavations in 1998–2002, which left the cave unsafe, and reportedly destroyed many of the cave’s speleothems.

Map of Marmarospilia, rebranded as ‘Cave of Nymphs’: sign located at cave entrance, photographed by Teun de Visser, July 2026. The scale (at right) appears to be in decimetres: another part of the sign reports that the ‘big chamber’ is 10 by 13 metres. (Image source: Google Maps).

Melissani is actually an underground lake in a sinkhole, which was exposed when the roof collapsed in the 1953 earthquake. No scholars have identified it with Odysseus’ Nymph cave (so far as I know), but some tourism materials do, probably because it is extremely colourful with the roof gone. A cave on Kefalonia is under consideration thanks to the theory that ‘Homer’s Ithake’ shouldn’t be identified with modern Ithaki but with the Paliki peninsula of western Kefalonia (though Melissani is not on Paliki).

The Paliki theory is associated with Spiridon Marinatos and Robert Bittlestone. It’s motivated by two false assumptions: (1) Homer is always realist, and the job of modern researchers is to find the reality that corresponds to Homer; (2) geographical descriptions in the Odyssey are always rigorously accurate. Bittlestone, for reference, localises Odysseus’ cave at a hypothetical cave that he thinks must have once existed at Atheras Beach, which he calls ‘Phorcys Bay’ in anticipation of his own theory (Bittlestone 1998: 418–431).

Homeric allegories

When Porphyry wrote his essay on the cave, there was already a long-standing tradition of interpreting Homer allegorically. Where some modern fans like to pretend everything in Homer is literally real, the ancient allegorists liked to treat the poems as hidden knowledge in code. A notable work is Herakleitos’ Homeric problems (1st/2nd century CE), which sees all kinds of meteorological, psychological, and cosmogonic symbolism in Homer. But the tradition goes back centuries: way back in the 6th century BCE Theagenes of Rhegion was already interpreting Homer’s gods as metaphors for natural forces — Hera = air, Hephaistos = fire, and so on.

Herakleitos: see Russell and Konstan 2005. Theagenes: schol. B on Iliad 20.67 (= Porphyry, Homeric questions on the Iliad ad 20.67–75 ed. MacPhail).

In reality, the Odyssey is a fictional narrative designed to be transparent. A sane reading shouldn’t be either realist or allegorical.

Having said that, there are cases of symbolism in Homer. But to look for legitimate cases, we have to explain Homer from Homer. If there’s symbolism, we find it by comparing how Homer operates in other contexts.

For example, hospitality is genuinely symbolic. It’s a cipher for virtue or vice. We know this because it’s a common pattern: a character’s behaviour in a hospitality type scene shows whether they are a good civilised person (they welcome guests into their home properly, they behave well when they visit others) or an uncivilised threat that has to be eliminated (they abuse their host or their guests). Homer uses formulaic scenes to send very specific ethical messages.

What about the cave? Is there legitimately any coded symbolism, whether or not it agrees with Porphyry’s analysis? Well, let’s review the physical features of the cave:

• located next to an olive tree at the head of a bay
• stone ‘jars’ and ‘amphoras’ that act as beehives
• stone ‘looms’ with colourful ‘cloths’
• running water
• two entrances, to north and south

We don’t need to imagine that this is realist in the sense of being a specific real cave on Ithaki; but individual features in isolation may be inspired by features that exist in real caves.

The text specifies that the Nymphs are Naiads: that implies that the running water is a freshwater spring. Some modern readers have reasonably interpreted the stone jars, amphoras, and looms as stalagmites or stalactites. That’s clearest in the case of the ‘looms’: the ‘cloths’ must surely be inspired by flowstone formations.

Flowstone: travertine drapery, also known as cave ‘bacon’, photographed by James St. John in Shenandoah Caverns, Virginia, USA. Pure travertine is white; the coloration here is produced by iron oxides. (Image source: Flickr.com)

No symbolism so far: this is just the text’s direct meaning. I don’t see any clear signs of symbolism in the olive tree, the speleothems, the bees, or the spring.

But the two entrances, one for mortals and one for gods? That’s definitely symbolic. Because it fits into a pattern that appears elsewhere in Homer and in other Archaic poetry.

Dualities: mortal and immortal, real and unreal

The closest parallel for the cave’s two entrances is in Penelope’s account of how dreams work (Odyssey 19.560–569).

Stranger, dreams are stories impossible to work out,
and not all of them work out for humans.
For fleeting dreams have have two gates:
one is made of horn, and the other of ivory.
The ones that come through the sawn ivory,
those ones cheat you: their words are irrelephant.
But the ones that come through the door of sawn horns,
truth is deer to them, whenever someone sees one of them.
I do not think my strange dream came from there,
though it would be good news for me and my son if it did.

By the way, the wordplays aren’t jokes: in Greek, the ‘ivory’ (elephas) dreams are cheaters (elephairontai), and the ‘horn’ (keras) dreams accomplish things (krainousi). In early Greek literature, wordplay is word magic.

Poems, dreams, and oracles are regularly cast in terms of two types of knowledge: truth and falsehood, divine and mortal, day and night, reality and opinion. The divine knowledge of the Muses is real, while mortal knowledge is just rumour or kleos (Iliad 2.484–486). At the same time, the Muses know both how to say false things that sound real, and also how to declare the truth (Theogony 27–28). Apollo warns that mortals who rely on valid omen birds will do well, but those who trust in vain birds will achieve nothing (Hymn to Hermes 543–549).

Gates and doorways are a particularly vivid bit of imagery for the two types of knowledge. In Penelope’s account, and in the cave of the Nymphs, one door is reserved for the mortal and the unreal. The other is for truth, the divine, and the real.

Compare how Parmenides passes the gates of Night and Day on his journey along the ‘road of the divinity’, travelling the path of knowledge:

Hastening to guide me to the light
the daughters of the Sun left the house of Night,
lifting the veils from their faces with their hands.
Here are the gates of the paths of Night and Day:
they have a lintel, and a stone threshold,
and the gates of aither fill the great doorframe.
Justice, goddess of payment, holds the keys of exchange.

Parmenides, On nature fr. B1.8–14

Rather than one gate for each type of knowledge, these gates are the barrier between day and night. Parmenides goes on to talk at length about the relationship between what is and what is not, and between truth and opinion. He does not name the goddess who instructs him in these things: the role of an oracle would typically be played by Night, as in the Derveni Theogony. When Justice allows him through the gates, it is ambiguous whether he is passing from day to night or from night to day; Hesiod, too, talks of Night and Day ‘exchanging’ as they pass the threshold of their house (Theogony 748–754).

Porphyry suggests that the mortal entrance to the cave of the Nymphs is for entering the cave, and the divine entrance for ‘those ascending to the gods’ (On the cave of the Nymphs 23). He singles out Parmenides, saying that Parmenides was thinking of Odysseus’ cave when he wrote about the gates of Night and Day. The symbolism is a bit more widespread than that. But Porphyry is certainly right in seeing that they’re related.

On the motif of ‘two types of knowledge’ see Gainsford 2015: 48–50. On mortal-immortal dualities in Parmenides, see Tor 2017: 227–250, with discussion of links to Porphyry and the cave of the Nymphs at 247–248.

References

• Antonaccio, C. M. 1995. An archaeology of ancestors. Tomb cult and hero cult in early Greece. London.
• Gainsford, P. 2015. Early Greek hexameter poetry. Cambridge. [Cambridge Core]
• Lamberton, R. (tr.) 1983. Porphyry. On the cave of the Nymphs. Barrytown (NY). [Internet Archive]
• Russell, D. A.; Konstan, D. (ed., tr.) 2005. Heraclitus: Homeric problems. Atlanta.
• Tor, S. 2017. Mortal and divine in early Greek epistemology. Cambridge.

Odysseus’ wanderings

Odysseus’ wanderings are the most famous sequence in Homer’s Odyssey. The Cyclops, the Lotus-eaters, and Circe are some of the epic’s most memorable parts, even though the wanderings as a whole occupy only one sixth of the poem.

On one level, they’re pretty clearly envisaged as taking place in an Otherworld, like a portal fantasy or isekai. On another level, they have strong links to real geographical locations. The Otherworld isn’t totally unreal. But the real places aren’t anything like how the Odyssey describes them. (For one thing, Sicily doesn’t have real Cyclopes.)

Real places, mythical footprints

The most straightforward example is Circe, the sorceress who uses magic potions to turn sailors into pigs. In Odyssey 10, Circe lives on an island in some indefinite location. But throughout antiquity, Circe’s home was always imagined to be at Monte Circeo in Italy, 90 km southeast of Rome.

Monte Circeo as seen from Terracina (image source: Wikimedia)

An epilogue to the Hesiodic Theogony has Circe and her family there ruling over the Tyrrhenians (a general Greek term for the people of western Italy); in the 500s BCE Rome founded a colony at Monte Circeo named after her, Circeii; a fragment of Aeschylus’ poetry refers to the Tyrrhenians as a ‘pharmakon-making race’, referring to Circe’s potions.

Hesiod: Theogony 1011–1016. Circeii: Livy 1.56.3; Dionysius of Halicarnassus 4.63.1. Aeschylus: eleg. fr. 2 West2.

Circe leaves footprints on the real place, even though she’s mythical. Her association with the area never faded: Apollonius again has her living in Italy in the Argonautica, she and her descendents are linked to founding legends for several cities in the area, and a Roman-era folktale gives her an Italian apprentice named Hals (‘sea’) who ends up turning Odysseus into a horse for the rest of his life.

Apollonius: Argonautica 3.310–313. Foundation legends: Telegonus as founder of Tusculum and ancestor of the gens Mamilia (Dionysius of Halicarnassus 4.45.1; Horace, Epistles 1.29–30; Livy 1.49.9; etc. etc.) and, in isolated sources, Praeneste (Aristokles, FGrHist 831 F2) and Caere (Servius on Aeneid 8.479); Telemachus as founder of Clusium (Servius on Aeneid 10.167). Hals turning Odysseus into a horse: Ptolemaios Chennos, in Photius’ Myriobiblon 190, 150.i.12–19 ed. Bekker; Sextus Empiricus, adversus Mathematicos 1.267; Servius auctus on Aeneid 2.44; schol. V on Odyssey 11.134.

So, an Otherworld, but also not. It's more like an imaginary prehistory: like Tolkien’s legendarium, or Robert E. Howard’s ‘Hyborian Age’ — except that Homer doesn’t redraw the coastlines of entire continents. He limits himself to relatively minor things like imagining that Monte Circeo was once an island.

‘Localisations’ baked into the Odyssey ... sort of

Similar things apply to the other stopovers in Odysseus’ wanderings. It’s just that they aren’t so well attested, or attested so early. There was some variation in where ancient people imagined each stopover as taking place, but many of them are pretty consistent:

• (book 9) Kikones — Thrace.
• Cape Malea, Kythera (specified by name in the Odyssey).
• Lotus-eaters — usually localised in Djerba (Tunisia).
• Cyclops — Sicily.
• (book 10) Aeolus — Isole Eolie (islands north of Sicily).
• Laestrygonians — Sicily.
• Circe (Aia) — Monte Circeo, Lazio.
• (book 11) soul-summoning, Nekyia, or ‘land of the dead’ — doublet: stated in the text to be beyond Oceanus among the Cimmerians, but soul-summoning was historically practised at Lake Averno, Campania, and Ephorus located the final home of the Cimmerians in Campania.
• (book 12) Sirens — Li Galli (islets south of Sorrento).
• Scylla and Charybdis — Strait of Messina.
• Cattle of the Sun (Thrinakia) — apparently Sicily (Thucydides gives Trinakria, ‘three-cornered’, as an old name for Sicily)
• Calypso (Ogygia) — various; sometimes localised in Atlantic Ocean

Sources: Kikones: Ismaros (Od. 9.39–40) is named for Lake Ismaris, Thrace. Malea and Kythera: Odyssey 9.79–81. Lotus-eaters: Polybius apud Strabo 1.2.17. Cyclops, Laestrygonians: Thucydides 6.2.1, etc. Aeolus: Thucydides 3.88. Circe: see main text. Nekyia beyond Oceanus: Od. 10.511, 11.13–22, 11.638–12.1. Nekyia among Cimmerians: Od. 11.14. Nekyia at Averno, in Campania among Cimmerians: Ephorus FGrHist 70 F 134a = Strabo 5.4.5; see further Ogden 2001: 23–24, 61–74. Sirens in Tyrrhenian Sea: Hesiod fr. 27 M-W (schol. on Apollonios Argonautika 4.892 states that Apollonios localises the Sirens on the same island as Hesiod), calling their island ‘Anthemoessa’. Sirens at ‘Seirenoussai’ (= Li Galli): Strabo 1.2.12, etc. Scylla and Charybdis at ‘Scyllaeum’, i.e. Strait of Messina: Polybius apud Strabo 1.2.15 (see further Phillips 1953: 59 n.66). Thrinacia: Sicily = Trinakria, Thucydides 6.2.2.

Odyssean Italy. In red: real Greek colonies that existed by ca. 650 BCE, around the time the Odyssey was composed (pale colour denotes doubtful cases). Blue: sites of Odyssean significance, either associated with the wanderings in the Odyssey, or linked to foundation legends involving Odysseus’ and Circe’s children.

Scholars tend to take the position that in the Odyssey itself, the wanderings are set in a purely imaginary Otherworld, and localisations for Odysseus’ stopovers are later developments. That's the position taken by Jonathan Burgess in his 2025 book The travels of Odysseus.

I mostly disagree. But in a nuanced way. To Greek colonists in Italy and Sicily, the ‘localisations’ of Odysseus’ wanderings felt very real. If you superimpose them on a map of Greek colonies that existed at the time, the wanderings look like a checklist of Greek colonies (in red, in the figure above) and trading partners (further north, especially in Etruria).

But this needs nuance. It’s instructive to look at Strabo’s long discussion of the geography of the Odyssey (Geography 1.2.7–33), and how it was treated by earlier scholars like Eratosthenes. It’s no good to say Homer’s geography is wholly fictional, as Eratosthenes did; but is equally wrong to say it’s strictly realist, as Strabo does.

You will find where Odysseus wandered when you find the cobbler who sewed up the bag of winds.

Eratosthenes, Geographica F5 Roller (= Strabo 1.2.15)

Eratosthenes is right to the extent that Homer’s geographical knowledge is poor, so poor that it barely counts as real. The myths are mythical. But they still echo real places.

First, as we’ve just seen, Circe was always placed at Monte Circeo. The setting for the Sirens is early too: from the 9th to the 5th centuries BCE, the Greek colony of what is now Naples was named Parthenope. Either Parthenope was considered to be one of the Sirens all along, or she became identified as a Siren sometime within that period.

The ‘localisations came later’ position is true in the sense that the Odyssey is mostly ignorant of the real geography. But it’s a bit like Dan Brown writing about Paris in The Da Vinci Code: the landmarks are real, but ... they’re wrong. Contemporary Greek colonists knew their way around Italy and Sicily; some sailors made it as far as Gibraltar. The epic knows these places exist. But it doesn’t have a clear idea of where they are or what they’re like. It doesn’t even know Ithaki!

Some of the Ionian islands as seen in Google Earth, looking westward (annotations in large type are mine). The real Ithaki is in the middle of the group; by contrast, the Odyssey thinks that Ithakē ‘lies furthest out in the sea towards the sunset, and the other islands are towards the dawn and the sun’ (9.25–26). If you think Homer’s geographical information is realist and accurate, you might want to instead localise ‘Ithakē’ on the Paliki peninsula of Kefalonia, as Marinatos did. But the Odyssey is an epic, not a carefully-researched geographical survey.

The colonists who lived in these places couldn’t help but find the story real — just as Homer’s Ithaca, even with its wild inaccuracies, feels real to the people who live on Ithaki today. Modern tourism maps of Ithaki are studded with Odyssey-themed locations.

In that nuanced sense, the localisations were baked in right from the start. The Odyssey isn’t clear on where Monte Circeo is, but it knows Circe lived somewhere along the Italian coast. It doesn’t know the Bay of Naples, but it knows that soul-summoning was practised at a lake near Cumae. It doesn’t know the layout of Sicily, but it knows that there are Greek colonists living on an island called Trinakria ‘three-cornered’ (or Thrinakia, adjusted to make it fit into dactylic hexameter).

Modern Odysseus-hunters love to come up with their own localisations, of course. That kind of mindframe takes a realist reading of the Odyssey, confident that every geographic detail is literally true — well, except the inconvenient details, naturally. I recommend against engaging with them (unless it’s to plunder them for citations of ancient geographical sources).

Lycophron’s Odyssey

The Odyssey’s understanding of Italian geography is shaky, but the 3rd century BCE poet Lycophron has much more detailed knowledge.

Lycophron’s Alexandra is a 1474-line mythological poem in iambic trimeter. It’s framed as a prophecy uttered by Cassandra about the horrible fates that await the Greeks who are going to destroy Troy. Lines 648 to 819 deal with Odysseus’ wanderings and his death.

For commentaries on the Odyssean part of the poem, see Schade 1999; Hurst 2008: 190–228; Hornblower 2015: 273–317. On Odysseus’ attachments to Italy more generally, see Phillips 1953.

The Alexandra is framed in obscure language, and densely packed with outrageously esoteric allusions. Here’s a taster, the bit about Odysseus’ death at the hands of Telegonus:

Finally, like a bird running on the waves,
worn down by brine on all sides like a shellfish,
finding his wealth squandered in the feasting of the Pronians
along with the fiercely raging Lacaenian woman,
wrinkled after escaping the sea’s shelter, he will die
with weapons, a crow, near Neritonian groves.
A deadly point will strike his side and kill him
with the sting of a Sardinian fish, impossible to heal.
His offspring will be called his father’s butcher,
the maternal cousin of Achilleus’ bride.

Lykophron, Alexandra 789–798

There are many obscurities to explain here:

• ‘Pronians’: Penelope’s Cephallenian suitors. The Prōnnoi were the people of a city on Cephallenia (Thucydides 2.30).
• ‘Lacaenian woman’: Penelope as Laconian. Her father Icarius was the brother of Tyndareus of Sparta.
• ‘fiercely raging’: in some non-Homeric variants, Penelope actively colluded with the suitors, or even had sex with all of them (thereby engendering the god Pan).
• ‘escaping the sea’s shelter’: a kenning for a ship; i.e. escaping a life at sea.
• ‘crow’: emblematic of extreme old age.
• ‘Neritonian groves’: Mt Neriton, on Ithaca. This line seems to presuppose a story that Odysseus is warned by an oracle or a dream that his son will kill him, and he goes into hiding in the hills (this story appears explicitly in ‘Dictys of Crete’ 6.14, 1st/2nd century CE).
• ‘sting of a Sardinian fish’: Telegonus uses a spear tipped with the venomous sting of a ray. Other sources don’t discuss the ray’s origin. ‘Sardinian’ (across the Tyrrhenian Sea from Lazio) evokes a story that the Sardinians allegedly euthanised their elderly, using a poison that produced a rictus grin known popularly as the ‘Sardonic smile’.
• ‘His offspring’: Telegonus, son of Odysseus and Circe.
• ‘maternal cousin of Achilleus’ bride’: cousin of Medea. Medea is in fact Circe’s niece, and in some traditions she marries Achilleus in the afterlife. (This translation interprets αὐτανέψιος as ‘maternal cousin’ by analogy with αὐτοκασίγνητος and αὐτάδελφος, ‘brother by the same mother’.)

As you can imagine, this is a poem that really needs accompanying notes.

It’s also controversial whether it’s really by Lycophron, and whether it’s the work of a single poet or a synthesis written in multiple periods. To my eyes, most of the doubts are motivated by a refusal to accept that Odysseus’ wanderings were deeply embedded in the Italian landscape all along.

Lycophron’s version of the wanderings covers most of the same ground as the ‘standard’ localisations above, though in a different sequence:

• Alexandra 648. Lotus-eaters: Odysseus will visit Syrtis (Gabès, near Djerba) and ‘the plains of Libya’ (not the modern country but the ancient Greek name for all of northern Africa).
• 649–652. Scylla: the ‘hybrid’ at the ‘Tyrrhenian strait’ (Strait of Messina).
• 653. Sirens, the ‘harpy-limbed nightingales’ on their rocks.
• 659–661. The Cyclops, the ‘fierce one-eye’ who will drink Odysseus’ wine.
• 662–665. Laestrygonians, the ‘remnant’ left unslain by Heracles.
• 666–672. Further references to Charybdis, Scylla, and the Sirens.
• 681–693. Consultation of the dead, set close to Ischia (‘the island that crushed the back of the Giants’) and the Greek colony at Pithecusae (where Zeus put ‘a race of apes’, pithēkoi).
• 694–711. Baiae, Cumae, and Lake Averno. Odysseus passes the tomb of his steersman Baius; the ‘Cimmerians’ (placed at Cumae also by Strabo, Geography 5.4.5); and the ‘Acherousian waters’, i.e. lakeside oracle of the dead, at Aornos, the Greek name for Averno.
• 712–737. The death of the Sirens, throwing themselves into the Tyrrhenian Sea. Parthenope washes ashore near the river Clanio (north of Naples) and receives cult honours from the Neapolitans; Leucosia washes ashore at ‘the rock that bears her name’, i.e. Licosa, south of Paestum; Ligeia washes ashore at Terina, an ancient city near the coast, west of Catanzaro.
• 738–748. Calypso, the ‘daughtter of Atlas’. Location not specified; but the relationship with Atlas implies somewhere near or beyond the Atlas mountains and Gibraltar.
• 749–761. A non-Homeric interlude where Odysseus visits the sea god Glaucus. Location not specified, but Glaucus has links of his own to Italy.
• 761–765. Cercyra (often regarded as a localisation of Homeric Scheria, the land of the Phaeacians): the ‘isle of the sickle’.
• 766–788. Return to Ithaca: the events of Odyssey 13–24.
• 789–798. Odysseus’ death at the hands of his and Circe’s son Telegonus.
• 799–811. Odysseus in both northwest Greece and Italy: he receives cult honours among the Eurytanians and Trampya (Aetolia and Thesprotia, in Greece), and is buried at ‘the hill of the Tyrrhenians in Gortynaia’ (Cortona, in Italy). This geographical duality mirrors a similar duality in the lost Telegony, whose first part was set in Thesprotia, with the second part beginning and ending at Circe's home in Italy.

Later in the poem at lines 1236–1245 there’s also a scene where Aeneas encounters Odysseus while travelling in Etruria, and they combine forces. This alludes to an eccentric tradition attested in fragments of Hellanicus and Damastes that the two of them founded Rome together (New Jacoby 4 F 84, 5 F 3). The context for these fragments is obscure, but sits well with the other foundation legends associated with Telemachus and Telegonus dotted around Latium and Etruria.

References

• Burgess, J. 2025. The travels of Odysseus. Oxford. [DOI]
• Hornblower, S. 2015. Lykophron. Alexandra. Greek text, translation, commentary, and introduction. Oxford.
• —— 2018. Lykophron's Alexandra, Rome, and the Hellenistic world. Oxford.
• Hurst, A. 2008. Lycophron. Alexandra. Paris.
• Ogden, D. 2001. Greek and Roman necromancy. Princeton.
• Phillips, E. D. 1953. ‘Odysseus in Italy.’ Journal of Hellenic Studies 73: 53–67. [JSTOR]
• Schade, G. 1999. Lykophrons ‘Odyssee’. Alexandra 648–819. Berlin. [DOI]

Fact-check: Eratosthenes (IBM, 1961) (video)

Video review/fact-check of the IBM short film ‘Eratosthenes’ (1961).

How Eratosthenes measured the earth. Part 4

1. The spherical earth | 2. Eratosthenes’ method | 3. Distance | 4. Angle of the sun

(e) Angle of the sun

Eratosthenes didn’t use gnomons to measure the sun’s angle.

Here once again I have to digress from telling the true story, and dispel a myth. It’s a myth that even many specialists take for granted. I’m just as guilty: in the past I’ve repeated the popular wisdom that Eratosthenes’ measurement was based on gnomon readings. Well, I was wrong.

The sun at midday (source: Stellarium)

The gnomon is the most basic instrument for measuring the sun’s motion. It’s a vertical rod casting a shadow on a horizontal surface. Egyptian observers had been thoroughly familiar with gnomons for many centuries before the Ptolemaic era. Gnomons had several uses:

1. a way of expressing latitude
2. determining exact time of midday, dates of equinoxes and solstices
3. orientation (determining the direction of due north, south, etc.)

The first of these was a comparatively recent innovation: it doesn’t make sense to measure latitude until you know the earth is spherical. The idea is that latitude is expressed as the ratio between a gnomon and the length of its shadow, at midday at the equinox. This ratio is an indirect expression of the sun’s angle.

A gnomon reading measures the ratio of the gnomon to its shadow at midday. This diagram shows a reading taken on the equinox, when the sun’s rays are parallel to the earth’s equator. Using trigonometry, you can use this ratio to calculate the angle θ, since tan θ = o/a.

And this is exactly what Pliny the Elder does (1st century CE). He quotes gnomon readings taken at the equinox.

So in Egypt at midday on the equinox, the shadow of an umbilicus — what they call a ‘gnomon’ — measured a little over half of the gnomon. In the city of Rome, the shadow is one ninth longer than the gnomon. In the town of Ancona, it’s 1/32 more than that. And in the region of Italy called Venetia, the shadow is the same length as the gnomon.

Pliny, Natural history 2.182

Strabo gives the latitudes of Alexandria and Carthage in the same way (2.5.38). Now, remember from Part 2 that at midday on the equinox, the sun’s angle from the vertical is equal to your latitude. This means we can convert Pliny’s and Strabo’s figures to the modern way of expressing latitude — degrees away from the equator — by plugging them into a calculator and using the ‘inverse tan’ function.

	Gnomon reading	Calculated latitude	Actual latitude
Egypt	a little over 0.5	over 27°	24.1° (Aswan) to 31.2° (Alexandria)
Alexandria	0.600 (3/5)	31.0°	31.2°
Carthage	0.636 (7/11)	32.5°	36.9°
Rome	0.889 (8/9)	41.6°	41.9°
Ancona	0.920 (8/9 + 1/32)	42.6°	43.4°
Venice	1.00	45.0°	45.4°

These are reasonably accurate, apart from Carthage.

Note. Ptolemy also puts Carthage too far south, at 32.7°: Geography 4.3.7. And no, it isn’t because Strabo and Ptolemy are confusing Carthage with Leptis Magna — one might imagine that, since the Greek name of Leptis Magna, Neapolis ‘new town’, means the same as Carthage’s Punic name, Qrt ḥdšt ‘new town’. But Ptolemy lists Carthage and ‘Neapolis’ separately: see 4.3.13.

Our earliest evidence for the practice of using gnomon readings as a measure of latitude dates to Pytheas of Massalía in the 300s BCE. Pytheas’ book apparently started out by reporting the latitude of Massalía (modern Marseille).

Hipparchos says that in Byzantion the ratio of a gnomon to its shadow is the same as what Pytheas reports for Massalía ...

Pytheas fr. 6c Mette (Strabo 2.5.8; also fr. 6a, i.e. Strabo 1.4.4)

Elsewhere Strabo reports (2.5.41) that Hípparchos’ summer solstice gnomon ratio for Byzantíon is 120 : 41.8, that is, 2.871. That puts the sun’s angle from the vertical at 19.2°. Taking the earth’s inclination to the ecliptic as 23.8° in that era, that implies a latitude of 43.0° N. The real latitudes of Marseille and Byzantíon are 43.3° N and 41.0° N, respectively.

Pytheas’ book doesn’t survive. We aren’t actually told that he carried on taking gnomon readings on his trip into the North Sea. But it’s fairly strongly implied: we do hear about him reporting on the behaviour of the summer tropic at the Arctic Circle (Strabo 2.5.8).

People wrote books reporting gnomon readings in Africa too. In the early 200s BCE Philon, a Ptolemaic diplomat, reported gnomon readings and other observations of the sun in Meroë.

(Hipparchos states that) Phílon described the parallel of latitude at Meroë, and related it in his Voyage to Aithiopia. He stated that 45 days before the summer solstice the sun is directly overhead; and he reports the ratios of gnomons to their shadows at the solstices and equinoxes. Eratosthenes’ (figures) agree very closely with Philon.

Philon, FGrHist 670 F 2 (Strabo 2.1.20)

‘Agree very closely’ implies their figures weren’t exactly identical: that is, Eratosthenes had another source in addition to Philon. Eratosthenes was well equipped with gnomon readings, it seems.

The second use of gnomons — determining solstices, equinoxes, and the moment of midday — was of much longer standing in Egypt. The Egyptian economy depended on the flooding of the Nile, so the Egyptians were highly motivated to keep track of the solar year. Martin Isler points to reliefs dating back to the 20th century BCE which he explains as gnomons with a forked tip and held vertical by struts. These gnomons are taller than a person — much taller, in the second image below — and the forked tip is designed to improve precision.

Left and centre: reliefs depicting gnomons used in ritual contexts, from a chapel of Senusret I (1900s BCE, left) and the Pylon of Ramesses II at Luxor (1200s BCE, centre). Right: diagram illustrating the movement of the gnomon’s shadow. The view is from overhead, with the gnomon at the bottom of the diagram, casting a shadow upward. The fork on the gnomon is oriented east-west: as the sun transits, the fork improves precision in determining the exact moment of midday. (Source: Isler 1991)

The third use of the gnomon, determining true north, may be even older, though the merkhet was better suited to this purpose. The great pyramid complex at Giza, built in the 2500s BCE, is famously oriented so that the main buildings are aligned with the cardinal directions to a precision of around 0.08°. Gnomons probably weren’t the primary tool for achieving that, but they must certainly have been an important piece of ancillary equipment.

Note. Nell and Ruggles 2014 survey possible orientation methods used at Giza, arguing that the primary method was alignment with circumpolar stars; they allow that gnomons and merkhets served ancillary roles. A stellar method seems inevitable given that some pyramid complexes have slightly different orientations, and precession seems to be responsible for that. They find no suitable pairs of circumpolar stars, however. I suggest Phecta and Megrez, in the Great Bear (Gamma and Delta Ursae Majoris, the two stars on the left side of the ‘scoop’ of the ‘big dipper’). According to Stellarium they were at their closest to being in a north-south alignment in the year –2586, with right ascensions differing by just 1.28 s. That is, in 2587 BCE, when one of these stars was due north, the other would be just 0.005° east or west.

Isler goes on to describe further Egyptian refinements to the gnomon, including (a) the use of plumb bobs to ensure the gnomon is exactly vertical; (b) designs for handheld gnomons to be used by travellers; (c) in southern Egypt, the technique of leaning the gnomon towards due north at a fixed angle to compensate for the sun being directly overhead in summer.

By Eratosthenes’ time, then, the gnomon was fully developed. The idea of using it as a measure of latitude was new-ish, but it worked well — and to judge from Pytheas’ measurement at Massalia, under ideal conditions it could be quite accurate.

But there’s a problem. A gnomon measurement is a ratio between two lengths. How do you convert a ratio to an angle?

You could use the inverse tan function, as I mentioned. Just one snag: trigonometric functions are a modern thing. Aristarchos had started to dabble in trigonometric inequalities, but he was a long way from developing the Taylor series, which is what modern calculators use to compute trigonometric functions. Hipparchos apparently computed a table of chord lengths in a circle, which implicitly draws on the sine function: that sounds good. But Hipparchos himself states that he reckoned the circle in 24 portions, that is, in steps of 7.5°. When Ptolemy quotes latitudes, they’re precise to 1/12 of a degree! Hipparchos’ trigonometric table absolutely didn’t have that kind of precision.

And that’s just one angle. Comparing two angles compounds the inaccuracies.

Note. Hipparchos using steps of 7.5°: commentary on Aratos, 148,26–150,3 Manitius. See also Neugebauer 1975: 299–300, with a reconstruction of Hipparchos’ chord table at 1132 (Table 8).

Moreover, if Eratosthenes had quoted gnomon readings for Alexandria, Syene, and Meroë, then it’s a little remarkable that none of the figures are quoted in any source. It’s not like they’d be hard to express. The real latitudes are 31.2°, 24.1°, and 16.9°. If ancient sources quoted equinoctial ratios of 3/5, 4/9, and 3/10, those would be close enough: they’d translate to latitudes of 31.0°, 24.0°, and 16.7°. But only the first ratio appears in any ancient source, and it isn’t in connection with Eratosthenes (Strabo 2.5.38).

The only numerical figure we get that is actually related to Eratosthenes’ angular measurements is this one.

So the distance from Syene to Alexandria must be 1/50 of a great circle of the earth.

Eratosthenes, Measurement M6 Roller (Kleomedes 1.7, 100,19–21 Ziegler)

Eratosthenes jumped directly to the angular measurement, as a proportion of a circle. He didn’t stop and invent trigonometry on the way. Gnomons must have served only an ancillary role, just as they did at Giza 2300 years earlier. Eratosthenes’ measurement wasn’t done with gnomon readings.

Irina Tupikova (2018) suggests that the instrument he used instead was the skáphē, a bowl with a gnomon sticking up out of the centre and gauge markings along the side of the bowl indicating the number of degrees from the vertical. I’ll accept that that’s possible, but I doubt ancient skáphai were capable of the necessary precision. (The precision of the skáphē isn’t attested or well studied.)

A much likelier candidate is a device described by Ptolemy in the 100s CE. This device has the advantage that there’s evidence of it being used at Meroë in the 200s BCE.

We make a bronze ring of a suitable size ... We use this as a meridian circle [i.e. oriented north-south], by dividing it into the normal 360° of a great circle, and subdividing each degree into as many parts as [the size] allows. Then we take a smaller ring, and fit it inside the first ... the smaller ring can rotate freely inside the larger, with a north-south motion, in the same plane. At two diametrically opposite points on one lateral face of the smaller ring we fix little plates, of equal size, pointing towards each other and the centre of the rings ... [W]e observed the sun’s movement towards the north and south by turning the inner ring at noon until the lower plate was completely enshadowed by the upper one. When this was the case, the tips of the pointers indicated to us the distance of the sun from the zenith in degrees, measured along the meridian.

Ptolemy, Almagest 1.12 (64,12–66,4 Heiberg, tr. Toomer)

Left: the instrument described by Ptolemy (base image: Toomer 1984: 61). The instrument is lined up north-to-south, with the meridian; at midday the inner ring is turned so that A casts its shadow on B, then the angle of the sun is read on the outer ring. Right: a 2nd century BCE graffito from Meroë depicting a seated observer using a similar device, with the sun at top left (source: Garstang 1914, Plate VI No. 1). Garstang (1914: 4) and Depuydt (1998: 173–176) interpret the device as a ‘transit instrument with circle’, i.e. Ptolemy’s device, combined with ‘an azimuth instrument’, i.e. a gnomon, represented by the vertical line extending upward from the ring and touching a sunray.

In 1914 John Garstang described a building in Meróë, dating to the 2nd century BCE, whose outside wall contained graffiti with astronomical calculations and observations. One graffito (above, right) showed something close to Ptolemy’s ring transit device.

Gnomons still had their uses. You’d need one to pinpoint the direction of the meridian, and the exact moment of midday/ And they weren’t made obsolete by Ptolemy’s device: a gnomon doesn’t require as much precision in its engineering.

But when Kleomedes reports that Eratosthenes measured the distance from Syene to Alexandria as 1/50 of a great circle of the earth, we should take it that he means exactly what he says. Eratosthenes didn’t do trigonometry on two gnomon ratios in order to compare them. He directly compared two angular measurements.

(f) The upshot

Most people, if they know anything about Eratosthenes’ measurement, learned about it from Carl Sagan in his 1980 TV series Cosmos.

Eratosthenes’ only tools were sticks, eyes, feet, and brains — plus a zest for experiment. With those tools he correctly deduced the circumference of the earth to high precision, with an error of only a few percent.

Carl Sagan, Cosmos episode 1 (first broadcast 28 Sep. 1980)

This is mostly false. Sagan both diminished and exaggerated the accomplishment.

Eratosthenes was standing on the shoulders of giants. Sagan’s version diminishes the huge amount of work done by previous explorers, researchers, astronomers, and writers; the political infrastructure, the rich publication history, the high precision instrumentation. He glosses over the reasoning and the tools that Eratosthenes himself devised: the most sophisticated geographer of his time, the inventor of lines of latitude and longitude, and the principle that observations at the same meridian can be directly compared.

At the same time, by looking only at Hultsch’s selectively reported result, he also glosses over the blunders and the inaccuracies. The Ptolemaic understanding of the route of the Nile leaves a lot to be desired; the distance measurements are pretty poor; and it turns out that while shadow lengths can tell you your latitude accurately under ideal conditions, they’re not very reliable.

In light of all that, it’s lucky for Eratosthenes’ modern reputation that his measurement was only 16% high. It remained the most accurate measurement of the earth’s size until the modern era. But there was no way at the time for anyone to be sure of that — no one knew Eratosthenes’ measurement was the most accurate one, until modern measurements improved on him!

It’s only in hindsight that we know the techniques and technology he used were the very best that were available. The principle of his measurement, however, was impeccable. Eratosthenes should be given credit for his methodology, more than for his lucky result.

References

• Borchardt 1921. ‘Ein weiterer Versuch zur Längenbestimmung der ägyptische Meilen (itr-w).’ In: Regling, K.; Reich, H. (eds.) Festschrift zu C. F. Lehmann-Haupts sechzigstem Geburtstage. Wien/Leipzig. 119–123.
• Bowen, A. C.; Todd, R. B. 2004. Cleomedes’ lectures on astronomy. Berkeley/Los Angeles.
• Bruins, E. M. 1964. Codex Constantinopolitanus Palatii veteris no. 1, 3 vols. Leiden.
• Carlos Carman, C.; Evans, J. 2015. ‘The two earths of Eratosthenes.’ Isis 106: 1–16. [JSTOR]
• Couprie, D. L. 2011. Heaven and earth in ancient Greek cosmology. New York.
• Depuydt, L. 1998. ‘Gnomons at Meroë and early trigonometry.’ Journal of Egyptian archaeology 84: 171–180. [JSTOR]
• Diels, H.; Kranz, W. 1960. Die Fragmente der Vorsokratiker, 9th ed. Berlin. [Internet Archive: vol. 1, vol. 2] (Note: see Kirk and Raven 1957 for a selection of the fragments, with English translations in the footnotes, and cross-referenced to Diels & Kranz)
• Duncan-Jones, R. P. 1980. ‘Length-units in Roman town planning: the pes monetalis and the pes drusianus.’ Britannia 11: 127-33. [JSTOR]
• Garstang, J. 1914. ‘Fifth interim report on the excavations at Meroë in Ethiopia. Part I. General results.’ Annals of archaeology and anthropology (Liverpool) 7: 1–10. [Google Books]
• Hultsch, F. 1882. Griechische und römische Metrologie, 2nd ed. Berlin. [Internet Archive]
• Isler, M. 1991. ‘The gnomon in Egyptian antiquity.’ Journal of the American Research Center in Egypt 28: 155–185. [JSTOR]
• Kirk, G. S.; Raven, J. E. 1957. The presocratic philosophers. A critical history with a selection of texts. Cambridge. [Internet Archive] (cf. Diels and Kranz 1960)
• Loret, V. 1903. ‘L’átour et la Dodècaschène.’ Sphinx: revue critique embrassant le domaine entier de l’égyptologie 7: 1–24. [Persée]
• Mette, H. J. 1952. Pytheas von Massalia. Berlin.
• Nell, E.; Ruggles, C. 2014. ‘The orientations of the Giza pyramids and associated structures.’ Journal for the history of astronomy 45.3: 304–360. [DOI]
• Neugebauer, O. 1975. A history of mathematical astronomy. Berlin/Heidelberg.
• Priskin, G. 2004. ‘Reconstructing the length and subdivision of the iteru from late Egyptian and Graeco-Roman texts.’ Discussions in Egyptology 60: 57-71. [Academia.edu preprint]
• Roller, D. W. 2010. Eratosthenes’ Geography. Princeton.
• Tupikova, I. 2018. ‘Eratosthenes’ measurements of the earth: astronomical and geographical solutions.’ Orbis terrarum 16: 221–254. [Academia.edu]
• —— 2022. ‘A common-sense approach to the problem of the itinerary stadion.’ Archive for the history of exact sciences 76: 319–361. [DOI]

Further scholarschip on the stadion:

• Engels, D. 1985. ‘The length of Eratosthenes’ stade.’ American journal of philology 106: 298–311. [JSTOR]
• Gulbekián, E. 1987. ‘The origin and value of the stadion unit used by Eratosthenes in the third century B.C.E.’ Archive for history of exact sciences 37: 359–363. [JSTOR]
• Oxé, A. 1963. ‘Die Masstafel des Julianus von Askalon.’ Rheinisches Museum 106: 264–286. [Universität zu Köln | JSTOR]
• Pothecary, S. 1995. ‘Strabo, Polybius, and the stade.’ Phoenix 49: 49–67. [JSTOR]
• Priskin, G. 2004. ‘Herodotus on the extent of Egypt.’ Göttinger Miszellen 201: 63–67. [Academia.edu preprint]

Further scholarschip on the measurement of the earth:

• Diler, A. 1949. ‘The ancient measurements of the earth.’ Isis 40: 6–9. [JSTOR]
• Drabkin, I. E. 1943. ‘Posidonius and the circumference of the earth.’ Isis 34: 509–512. [JSTOR]
• Dutka, J. 1993. ‘Eratosthenes’ measurement of the earth reconsidered.’ Archive for the history of exact sciences 46: 55–66. [JSTOR]
• Nissen, H. 1903. ‘Die Erdmessung des Eratosthenes.’ Rheinisches Museum 58: 231–245. [Universität zu Köln | JSTOR]
• Priskin, G. 2006. ‘The Egyptian heritage in the ancient measurements of the earth.’ Göttinger Miszellen 208: 75–88. [Academia.edu preprint]
• Rawlins, D. 1982. ‘Eratosthenes’ geodesy unraveled: was there a high-accuracy Hellenistic astronomy?’ Isis 73: 259–265. [JSTOR]
• Russo, L. 2013. ‘Ptolemy’s longitudes and Eratosthenes’ measurement of the earth.’ Mathematics and mechanics of complex systems 1.1. 67–79. [DOI]
• Taisbak, C. M. 1974. ‘Posidonius vindicated at all costs? Modern scholarship versus the Stoic earth measurer.’ Centaurus 18: 253–269. [DOI]

How Eratosthenes measured the earth. Part 3

1. The spherical earth | 2. Eratosthenes’ method | 3. Distance | 4. Angle of the sun

Distances along stretches of the Nile as Eratosthenes described them in his Geography, fr. 98 Roller (see below for details). The ‘5300 stadia’ from Alexandria to Syene may include a 300 stadia region around Syene where the sun was overhead at the summer solstice; alternatively the extra 300 stadia could be explicable by Priskin’s theory that the 5300 stadia represent a conversion from 106 Egyptian schoinoi or itrw at the rate of 50 : 1.

(d) Distance

Distances quoted by Eratosthenes

Eratosthenes’ chosen sites were Meroë, Syene, and Alexandria. He reckoned the straight-line distance between each pair as 5000 stadia.

[T]he meridian through Syene is drawn roughly along the course of the Nile from Meroë to Alexandria, and the distance is about 10,000 stadia. And Syene is situated halfway between them, that is, 5000 stadia from Meroë.

Eratosthenes, Geography fr. 34 Roller (Strabo 2.5.7)

So the distance from Syene to Alexandria must be one fiftieth of a great circle of the earth: and this is 5000 stadia. Therefore, the entire circle works out to be 250,000 stadia. And this is how Eratosthenes’ calculation goes.

Eratosthenes, Measurement M6 Roller (Kleomedes 1.7, 100,19–23 Ziegler)

From Syene to Meroë, Timosthenes the commander of Philadelphos’ fleet gave no measurement but said it was a journey of 60 days; Eratosthenes gave it as 625 [Roman] miles; Artemidoros, 600 miles.

Pliny, Natural history 5.59

Note. The third passage doesn’t appear in Roller’s edition of the Eratosthenes fragments, for some reason. Pliny’s figure of 625 miles represents 5000 stadia: a Roman mile was 5000 Roman feet. At 2.85 and 12.53 Pliny quotes the rate of 1 stadion = 625 Roman feet = 1/8 of a Roman mile.

How did he obtain this distance? The most popular answer is based on Martianus Capella, writing in the 5th century CE:

In fact Eratosthenes was informed by Ptolemy’s royal surveyors [mensores regios] about the number of stadia from Syene to Meroë ...

Martianus Capella 6.598

At this point we could go on a long tangent. Were these mensores a special category of surveyor known as ‘bematists’? What does that job title entail, exactly? It’d take half an hour. Let’s cut to the chase. Martianus’ mensores weren’t military survey technicians, counting footsteps or wheeling a hodometer through hundreds of kilometres of trackless desert. Or if that is what Martianus imagined, then he’s just wrong.

Some of the scenery on the direct route between Syene and Meroë. (Base image: Google Earth)

Eratosthenes used reports published in books that were readily available. And these books described the course of the Nile, not the straight-line desert route between Syene and Meroë.

First, in his Geography he said that he simply repeated the distances he found quoted in these reports, without verifying them.

Eratosthenes states that, for more remote regions, he reports distances that have been handed down, and that he has not verified them but repeated them as he has received them. But sometimes he adds, ‘in a more or less straight line.’

Eratosthenes, Geography fr. 131 Roller (Stabo 2.1.41)

Second, we have independent testimony about Greek-speaking writers describing routes and distances between Syene and Meroë. Several Ptolemaic figures travelled to Meroë and beyond, and wrote books about their observations: Dalion, Aristokreon, Bion, Simonides, Philon, Timosthenes, Basilis — and these are just the ones we know about. Pliny tells us that four of these writers explicitly reported distances south of Syene (though he doesn’t report their figures), and that some of them reckoned the total distance from Meroë to the Mediterranean coast as 1250 Roman miles (10,000 stadia).

These people were explorers, admirals, diplomats. They weren’t trundling hodometers along the riverbank, and they certainly weren’t counting paces.

Note. Pliny, Natural history 6.183. Dalion sailed further up the Nile beyond Meroë and described the wildlife (FGrHist 666). Eratosthenes did not draw on Aristokreon’s account (Aristokreon quoted the distance from Syene to the Mediterranean as 750 Roman miles, i.e. 6000 stadia; FGrHist 667 F 1 = Pliny, NH 5.59). Bion wrote a description of the ethnography and geography of Aithiopia and Nubia (FGrHist 668). Simonides wrote an account of his five years living in Meroë (FGrHist 669). Philon was an agent for the Ptolemaic government who wrote a Voyage into Aithiopia (FGrHist 670). Timosthenes, the naval commander, wrote a substantial account of his voyages (FGrHist 2051) in which he quoted a 60 day travel time up the Nile from Syene to Meroë.

Put these two points together, and you’ve got Eratosthenes describing the course of the Nile as follows.

For Eratosthenes says the Nile flows northward from Meroë for 2700 stadia; then it turns back southward, in the direction of the winter sunset, for 3700 stadia; after almost reaching the latitude of Meroë, and projecting a long distance into Libya, it makes its second turn northward for 5300 stadia, until it gets to the great cataract, turning slightly eastward; then 1200 stadia to the smaller cataract at Syene; then 5300 stadia further to the sea.

Eratosthenes, Geography fr. 98 Roller (Strabo 17.1.2)

Notice the nice round numbers. They aren’t pure guesswork: these people were experienced professionals, after all. But they weren’t whipping out a theodolite at every bend in the river.

We can only conjecture how Eratosthenes reckoned this meandering route as 5000 stadia in a straight line. In the second stretch, at least, his figures imply a bearing directly southwest. Further north, it isn’t clear where exactly he imagined the river ‘turning slightly eastward’. The 1200 stadia stretch from the great cataract to Syene surely represents the Triakontaschoinos, or ‘land of 30 schoinoi’: this is probably the origin of Pliny’s claim that Eratosthenes reckoned the schoinos as 40 stadia (see below). Here are some speculative reconstructions.

The Nile with two hypothetical reconstructions of Eratosthenes’ account of its route. Distances are in stadia. Left: the Nile with real locations marked. Centre: my suggestion for how Eratosthenes might have envisaged the upper Nile. Right: reconstruction by Rawlins 1982, overlaid on the real geography. Eratosthenes’ stated figures are in bold, other figures are calculated (by myself or Rawlins). My reconstruction preserves a distance of 5000 stadia between Syene and Meroë in a north-south line; Rawlins puts them at different longitudes, has an unattested 5300 stadia for the north-south distance between them, and doesn’t link the 1200 stadia section with the length of the Triakontaschoinos. Left and right base images are from Google Earth, with spherical geometry centred on the Syene meridian; centre image is on flat geometry.

Whatever the details, a lot of approximation was involved. It takes a lot of massaging to make Eratosthenes’ measures look like the real course of the Nile. And we certainly shouldn’t be imagining some poor sap counting footsteps through hundreds of kilometres of desert along the direct route.

Eratosthenes’ distances were travellers’ educated estimates. They weren’t exact measures carefully surveyed with high-precision equipment.

Note. Priskin 2004 argues that these distances, and the 5300 stadia from Syene to Alexandria in the same passage, are derived from native Egyptian reckonings. The idea is that Eratosthenes drew on a Greek-language report in which distances in Egyptian schoinoi were converted to stadia at the rate of 50 stadia to the schoinos. I used to find this argument compelling, but it doesn’t stack up in light of the 3rd century BCE geographical literature mentioned above. Eratosthenes’ use of Timosthenes is directly attested (FGrHist 2051 T5–T8), and we know his figures had strong similarities to Philon’s (Geography fr. 40 Roller = FGrHist 670 F 2).

The length of the stadion

So, we’ve got distances of 5000 stadia. What’s that in modern units?

Our evidence for the length of a stadion varies greatly in its character and usefulness. Here’s the executive summary: the stadion as a metrological unit was anywhere between 177 m and 192 m, with the most traditional figure being an eighth of a Roman mile, that is, 183–185 m.

It’s also been suggested that stadia could also act as an itinerary unit when measuring long distances. You can think of this distinction as scientific versus practical. In metrological units, the distance from New York to Los Angeles is 3940 km (2450 miles) as the crow flies. In itinerary units, it’s six or seven days’ drive.

We have three types of evidence for the stadion.

1. Physical ancient racetracks, the literal meaning of stadion. These range from 177.3 m (Delphi) to 192.3 m (Olympia).
2. Ancient sources report a variety of conversion rates to other reckonings, namely the Roman mile and the Egyptian schoinos.
3. Reports of long distance measurements may indicate that the stadion could also be an itinerary measure.

The first two categories are basically metrological. Ancient units aren’t as precise as modern units, but the Roman mile was relatively stable and precise. Modern scholarship has a habit of treating it as 1480 m, thanks to a 19th century study; a more recent study puts it anywhere in the range 1465 to 1481 m. One eighth of that puts the stadion at 183 to 185 m, in good agreement with the racetracks. We do hear of some variations — 7.5 stadia to the mile, or 8.25, or what have you — but nothing too serious.

Note. Duncan-Jones 1980: 127 reports on evidence for the centuria which implies a Roman foot of 292.92–296.25 mm, and therefore a mile of 1464.60–1481.25 m (1 Roman mile = 5000 Roman feet). The 19th century study is that of Hultsch 1882: 88–90, who reports a range for the foot of 295.5–297.0 mm. The 8 : 1 rate goes back at least to Polybios (2nd cent. BCE; 3.39.8).

As for the schoinos — that’s the Greek name; the Egyptian word was itrw, literally ‘river’ — modern scholars like to quote a prototypical length of 10.5 km. This figure was devised in the early 1900s from some sample distance measurements, in conjunction with the fact that 10.5 km happens to be a nice round multiple of Egyptian royal cubits: 20,000 royal cubits of 0.525 m = 10.5 km. (There is no documentary basis for the 20,000 cubit figure.)

Note. For the origin of the 10.5 km and 20,000 cubit figures, see Tupikova 2022: 322–323, citing Loret 1903 and Borchardt 1921.

Now, here’s what Pliny says about converting between the stadion, the Roman mile, and the schoinos.

By Eratosthenes’ reckoning, a schoinos is 40 stadia, that is 5 miles; some have given a rate of 32 stadia to the schoinos.

Pliny, Natural history 12.53

Three things to notice here.

• Pliny repeats the usual 8 : 1 conversion rate for the mile, implying a stadion of 185 m.
• If we instead started from a schoinos at 10.5 km, his figures would imply a mile of 2630 m and a stadion of 263 m or 328 m.
• The 40 : 1 rate probably comes from the distance of 1200 stadia that Eratosthenes quoted for the Triakontaschoinos or ‘land of 30 schoinoi’, from the great cataract northward to Syene.

The key to resolving this apparent inconsistency is that the schoinos was not normally a metrological unit. It was an itinerary unit: specifically, a chunk of a boat journey upriver (recall that itrw means ‘river’). It may have described a stretch of the Nile covered by one towing team (New Pauly s.v. ‘schoinos’).

So you’d expect its physical length would vary depending on terrain. And that’s exactly what ancient sources tell us.

[From Alexandria to the top of the Delta] Artemidoros states that the journey upriver is 28 schoinoi, which is 840 stadia, reckoning 30 stadia to the schoinos. But when I made the trip, they gave the distances using different reckonings in different places, so that they agreed on 40 stadia or even more to the schoinos ... Artemidoros himself [says] ... that from Memphis to the Thebaid the conversion is 120 stadia to the schoinos, and from the Thebaid to Syene it is 60 ...

Strabo 17.1.24

Pliny and Strabo make it crystal clear that they’re talking about variations in the length of the schoinos, not the stadion. They’re using stadia to express that variation. Pliny makes similar statements about the Persian schoinos (Natural history 6.125).

Lengths for the stadion based on racetracks and ancient conversion rates, treating them as if the mile and schoinos were metrological units of 1480 m and 10.5 km respectively. The ‘sane range’ for the stadion, in green, includes the physical racetracks, and all conversions with the Roman mile except for two late figures from Dío Cassius and Julian of Ascalon. A full tabulation of the sources and their conversion rates is given below in Appendix A.

Some modern reports are cautious enough about the schoinos to call the 10.5 km figure a convenient ‘average’. Even that’s doing it a kindness.

The upshot is that the schoinos is utterly useless for reconstructing other ancient units.

Note. In this series I wanted to tell the true story without distractions, but there’s no dodging some widely repeated falsehoods. The following claims come from Friedrich Hultsch (1882: 60–62), and they are all false. For fuller explanations see Appendix B below. Egyptian measurements were rigidly regulated by the royal cubit (0.525 m; ‘dem Ptolemäischen Maße ... welches nach dem genauen und beständigen Maßstabe der alten ägyptischen Königselle geregelt war’). The schoinos was ‘firmly determined’ (fest bestimmt) as 12,000 cubits. Different conversion rates reflect variations in the length of the stadion, not the schoinos. The length of the stadion is to be determined exclusively from (a) conversion rates with the schoinos in the pseudo-Heronic Geometrika (ii.6 = iii.5 Bruins) — though not the conversion rate that the Geometrika quotes for the mile! — and (b) Pliny’s statement that Eratosthenes used a 40 : 1 rate with the schoinos. The length of Eratosthenes’ stadion was 157.5 m. Eratosthenes commissioned ‘bematists’ to pace out distances.

Our useful metrological evidence boils down to the racetracks and the Roman mile. And as we’ve seen, they’re broadly in agreement, if not very precise: they produce a metrological stadion of 177–192 m, or let us say, 185 m ± 8 m.

It remains to consider the possibility of reckoning in itinerary stadia. A useful 2022 article by Irina Tupikova goes over this, looking at ancient sources generally, not just Eratosthenes.

Where distances quoted by ancient sources can be compared with the real distances, her analysis indicates that distances under 1000 stadia (in metrological terms, 185 km = 115 miles) tend to be significantly overstated. Distances over 1000 stadia are very variable, sometimes overstated, sometimes understated.

You can explain this in two basic ways:

1. Ancient surveying methods weren’t very accurate.
2. Distances between cities are a representation of journey times.

Take a modern analogy. Let’s say you’re aware that it’s six or seven days’ drive from New York to Los Angeles. If you accept a common reckoning that you can drive 800 km (500 miles) in a day, you can estimate the total distance as 4800–5600 km (3000–3500 miles). The real distance by road is 4500 km (2800 miles). (Why the discrepancy? All sorts of reasons: fatigue, terrain, supplies, accidents, etc.)

So we could say that the distance is 4800–5600 km in ‘itinerary kilometres’, which are about 7%–17% shorter than actual kilometres. I’m not saying this would be wise. But you could.

This is the kind of conclusion Tupikova reaches about stadia. For land distances over 125 Roman miles, Pliny the Elder reports distances which could be taken to suggest an ‘itinerary mile’ which is shorter than the 1480 m mile by 7% to 23%; for sea distances under 125 miles, his miles tend to be around 36% short. When Strabo reports distances from Eratosthenes’ Geography, they could represent an itinerary stadion around 13% to 31% short of the 185 m stadion.

If you take the ‘itinerary stadion’ at face value, Eratosthenes’ measurement turns out to be highly accurate. Tupikova reckons that the measure of 157.5 m represents Eratosthenes’ ‘itinerary stadion’: using that, his measurement of the earth’s circumference at 252,000 stadia is impressively precise: it comes to 30,690 km, just 0.79% shy of the true value.

Except that’s total nonsense. It’s circular. The argument goes: if we use distance units based on the figures that Eratosthenes gives for the distances between Alexandria–Syene–Meroë, then his measurement of the earth, which is also based on those same figures, turns out to be accurate too.

When you put it that way, the 0.79% precision isn’t quite so amazing.

That isn’t what the ‘itinerary kilometre’ and the ‘itinerary stadion’ are for. They don’t work like that. If someone travelling across America converted ‘six days’ drive’ to kilometres at the rate of 800 : 1, and you confronted them with the true metrological distance, they wouldn’t say: ‘Well actually I was working in itinerary kilometres, and in those, my measurement is perfectly precise.’ No: they’d admit that it was an estimate.

Eratosthenes would say the same. In fact he did say the same. Remember, he openly stated that he didn’t verify his figures.

Eratosthenes didn’t quote the distance from Syene to Meroë as 5000 stadia because he was using ‘Eratosthenean stadia’, and Eratosthenean stadia happen to be 1/5000 of that distance. He did so because he relied on imprecise measurements.

The circumference of the earth

We’re left with the metrological stadion, of 177–192 m. Using that standard, Eratosthenes’ figure of 5000 stadia for the distances Alexandria–Syene and Syene–Meroë is too high. 5000 stadia is between 890 and 960 km; the real distances, as the crow flies, are 840 km and 800 km respectively; the north-south separation, ignoring the different longitudes, is 790 km for both distances.

That puts Eratosthenes’ figure for the earth’s circumference between 44,680 km (stadia of 177.3 m) and 48,460 km (stadia of 192.3 m). The traditional reckoning of 8 stadia = 1 Roman mile (1480 m) gives 46,620 km. The earth’s true polar circumference is 40,008 km. Eratosthenes’ result is between 11.7% and 21.1% too high; the traditional reckoning is 16.5% high.

There’s no need to make excuses for that. This is still impressive for the 3rd century BCE. It doesn’t need to be accurate within 0.79% to be a terrific achievement. And it has to be said, given that Eratosthenes didn’t verify his data, he got lucky. The estimates he used could easily have been much wilder.

Next week, the finale: part 4, the problem of measuring the sun’s angle.

Appendix A. Table of ancient sources

Here I give the lengths of physical racetracks and ancient conversion rates between the stadion, schoinos, and Roman mile, treating them as if all three were metrological units.

Source	Conversion rate	Resulting length of stadion
Ancient racetracks (Gulbekian 1987: 360; New Pauly s.v. ‘stadion’)	—	177.3–177.5 m (Delphi) 181.3 m (Epidauros) 184.3–185.0 m (Athens) 191.4 m (Miletos) 192.25–192.30 m (Olympia)
Herodotos 2.6, 2.9	60 stadia = 1 Egyptian schoinos	175.0 m (schoinos = 10.5 km)
Herodotos 2.149; pap. Heidelberg 1289	1 stadion = 400 Egyptian cubits	210.0 m (royal cubit = 0.525 m)
Eratosthenes, reported by Pliny, Natural history 12.53	40 stadia = 1 schoinos	262.5 m (schoinos = 10.5 km)
‘others’, reported by Pliny, Natural history 12.53	32 stadia = 1 schoinos	328.1 m
Artemidoros, reported by Strabo 17.1.24	30, 60, or 120 stadia = 1 schoinos	350.0 m, 175.0 m, or 87.5 m
Strabo 17.1.24	30 or 40 stadia = 1 schoinos	350.0 m or 262.5 m
Geometrika (pseudo-Heron) ii.6, iii.5 Bruins	30 stadia = 1 schoinos 45 stadia = 1 ‘barbarian’ schoinos 60 stadia = 1 ‘Persian’ schoinos	(these illustrate that the schoinos is an itinerary measure, not metrological; also claims that the Roman mile = 5400 Roman feet)
Eratosthenes, reported by Pliny, Natural history 5.59, 2.85, 12.53	40 stadia = 5 Roman miles; Syene to Meroë (5000 stadia) = 625 Roman miles	185 m (mile = 1480 m)
Eratosthenes and Strabo, reported by Julian of Ascalon (i.201 Hultsch)	8¼ stadia = 1 mile	179.4 m (mile = 1480 m)
Polybios 3.39.8	8 stadia = 1 Roman mile	185 m (mile = 1480 m)
Polybios, reported by Strabo 7.7.4	8⅓ stadia = 1 Roman mile	177.6 m (mile = 1480 m)
‘most people’, according to Strabo 7.7.4	8 stadia = 1 Roman mile	185 m (mile = 1480 m)
Plutarch, Gaius Gracchus 7.2	a little under 8 stadia = 1 Roman mile	a little over 185 m (mile = 1480 m)
Censorinus 13.2	1 stadion = 625 Roman feet (⅛ mile)	185 m (mile = 1480 m)
Dio Cassius 38.17.7, 39.50.2, 46.44.4, etc.	7½ stadia = 1 Roman mile	196.1 m (assuming post-200 CE mile ≈ 1471 m: Hultsch 1882: 97)
Julian of Ascalon i.201 Hultsch	7½ stadia = 1 Roman mile	196.1 m (post-200 CE mile ≈ 1471 m)
Geometrika 22.1 Heiberg	7½ stadia = 1 mile = 4500 royal feet = 5400 ‘Italian’ feet	(meaning obscure; the ancient Roman mile = 5000 Roman feet)

Appendix B. Problems with Hultsch’s account of ‘Eratosthenes’ stadion’

• If the schoinos really were ‘firmly determined’, then the ‘average’ schoinos of 10.5 km would mean (a) at the 40 : 1 and 32 : 1 rates that Pliny quotes, the stadion was 263 m or 328 m; (b) Artemidoros’ reckoning would produce a stadion anywhere from 88 m to 350 m. Hultsch’s reckoning of 157.5 m doesn’t fit in here anywhere.
• All scholars in the last century have quoted a rate of 20,000 cubits in the ‘average’ schoinos, not 12,000 (see e.g. Priskin 2004; Tupikova 2022: 323). As we’ve seen, (a) even that’s just a byproduct of the 10.5 km reckoning, and (b) it’s far too precise, given that the schoinos is itinerary while the cubit is metrological.
• The only basis for the 12,000 cubit figure is the pseudo-Heronic Geometrika, which comes with its own problems.
• It’s idiosyncratic: e.g. it quotes the rates 1 ‘mile’ = 5400 ‘Italian’ feet = 4500 phileteric feet, rather than the 5000 foot standard.
• The Geometrika gives a rate of 30 stadia to the schoinos.
• The Geometrika treats all these units as metrological: this wasn’t the case in antiquity.
• The vocabulary of the Geometrika implies a Byzantine date. It refers to ‘Italian’ feet and miles rather than ‘Roman’, surely on the grounds that by the time it was written, ‘Roman’ included all of the units it lists. It was only around the 5th century CE that ‘Roman’ started to be used for the people of the eastern empire. The Geometrika should be grouped with Julian of Ascalon among sources too late to be relevant.
• Hultsch selectively disregards the 8 : 1 rate with the mile which Pliny attributes to Eratosthenes in the same sentence; the 8¼ : 1 rate with the mile which Julian of Ascalon attributes to Eratosthenes; the 30 : 1 rate with the schoinos in the Geometrika; and all of Polybios’, Artemidoros’, Strabo’s, and Plutarch’s testimony (among others).
• These selections are transparently aimed at trying to make Eratosthenes’ measurement work out to be as accurate as possible.
• The only basis for the notion of ‘pacing out distances’ is the etymology of the rare word βηματίζω ‘measure’. The primary meaning comes from the distance unit the βῆμα (‘pace’, usually 2.5 or 3 feet). Ultimately both are derived from βη- ‘walk’, but etymology isn’t a reliable guide to meaning. Prior to the Byzantine period βηματίζω appears only in contexts where literal measurement by pacing would be impossible (Dionysios Chalkous fr. 3.5 West) or where we know other measuring methods were used (Polybios 3.39.8).
• Although Hultsch’s account has long been rejected, much of his misinformation lingers. Popular accounts still accept without question that the stadion and the schoinos were 157.5 m and 12,000 cubits. Even Tupikova’s 2022 article gives airtime to the 157.5 m stadion, and the notion of surveyors pacing out distances.