c. 276–194 BCE · head of the Library · geographer · mathematician · chronographer · poet
Eratosthenes of Cyrene
Ἐρατοσθένης
In Alexandria: c. 245–194 BCE
The Suda says Ptolemy III summoned him from Athens. P.Oxy. 1241 makes him Apollonius's successor; the Suda's life of Apollonius also names him head of the Library, but as Apollonius's predecessor. That he taught the king's son, the future Ptolemy IV, is a modern inference, not stated: the papyrus calls Apollonius, whom he followed, a royal tutor, and Murray argues that the succession it records is in that post. He measured the circumference of the Earth from the angle of the noon sun at Syene and Alexandria, drew a map of the inhabited world, and founded scientific chronology. Nicknamed "Beta", second-best at everything; Archimedes sent him the Method.
Their life and work
Born at Cyrene about 276 BCE, he studied at Athens and came to Alexandria at Ptolemy III's call, following Apollonius as head of the Library. Cleomedes gives his method: at the summer solstice the sun stood overhead at Syene, while at Alexandria a gnomon's shadow showed it a fiftieth of a circle from the zenith; with the distance between the cities put at 5,000 stades, the whole circle came to 250,000. How long his stade was is still argued, so how close he came cannot be said exactly.
His Geographika, the work that gave geography its name, and his Chronographiai, which dated Greek history from the fall of Troy, survive only in what Strabo and later writers quote.
Our device: Their emblem is a bowl sundial. No portrait of any of these people survives. The emblems are our devices.
On the shelves
- Eratosthenes of Cyrene, On the Measurement of the Earth · c. 240–230 BCE · Lost
- Eratosthenes of Cyrene, Letter to King Ptolemy on Doubling the Cube, with the epigram on the Mesolabe · c. 240–220 BCE · Survives whole
- Eratosthenes of Cyrene, Hermes · c. 240–200 BCE · Survives in fragments
- Attributed to Eratosthenes, Catasterisms · 3rd century BCE original; epitome later · Survives in large part
- Eratosthenes of Cyrene, Geographika · c. 230–210 BCE · Survives in fragments
- Eratosthenes of Cyrene, Chronographiai and Olympic Victors · c. 230–200 BCE · Survives in fragments
Moments
- c. 260s–245 BCE · Apollonius of Rhodes at the head of the Library Known: probable, disputed
- c. 245 BCE · Eratosthenes summoned; he measures the Earth Known: attested
In the show
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Sources (8)
- Suda Eratosthenes, ε 2898 (opens in a new tab)
- Suda Apollonios, α 3419 (opens in a new tab)
- P.Oxy. X 1241 (ed. B. P. Grenfell and A. S. Hunt, The Oxyrhynchus Papyri X, London 1914) col. ii (opens in a new tab)
- J. Murray, "Burned after Reading: The So-Called List of Alexandrian Librarians in P. Oxy. X 1241", Aitia 2 (2012) (opens in a new tab)
- Cleomedes, Caelestia 1.7
- D. W. Roller, Eratosthenes' Geography (Princeton: Princeton University Press, 2010)
- Strabo, Geography 1.4; 2.1 (opens in a new tab)
- K. Geus, Eratosthenes von Kyrene: Studien zur hellenistischen Kultur- und Wissenschaftsgeschichte (Munich: C. H. Beck, 2002)