Posidonius was informed in his approach to finding the Earth's circumference by Eratosthenes, who a century earlier used the elevation of the sun at different latitudes to arrive at a figure of 250, 000 stadia ( which he rounded to 252, 000 so that it would be divisible by 60 ).

A formula used in Eratosthenes ' method is

Eratosthenes most probably used a solstitial armilla for measuring the obliquity of the ecliptic.

Still, combined with trigonometric evidence of the form used by Eratosthenes 1, 700 years prior, the Magellan expedition removed any reasonable doubt in educated circles in Europe.

This was the same process used by the ancient Greek Eratosthenes ( 276 – 196 BC ).

Eratosthenes used a simpler sexagesimal system dividing a circle into 60 parts.

Eratosthenes used this spelling, however Hipparchos wrote it as Κάνωπος.

Eratosthenes used his knowledge of geometry to measure the distance between the Sun and the Earth along with the size of the Earth.

That some of the figures Eratosthenes had used in his calculation were considerably in error became known, and Posidonius set out to get a more accurate measurement.

Ptolemy discussed and favored this revised figure of Posidonius over Eratosthenes in his Geographia, and during the Middle Ages scholars divided into two camps regarding the circumference of the earth, identified with Eratosthenes ' calculation on the one hand and Posidonius ' 180, 000-stadium measure on the other.

An example of the sort of attack this portrayal was intended to defend against can be found in two orations of Lysias, Against Eratosthenes and Against Agoratus ; there, Theramenes is portrayed as treasonous and self-interested, doing tremendous harm to the Athenian cause through his machinations.

The two towns were separated by one degree on the meridian, so from his measurement he was able to calculate a value for the circumference of the earth – a feat celebrated in the title of his book Eratosthenes Batavus ( The Dutch Eratosthenes ), published in 1617.

His work Eratosthenes Batavus (" The Dutch Eratosthenes "), published in 1617, describes the method and gives as the result of his operations between Alkmaar and Bergen op Zoom — two towns separated by one degree of the meridian — which he measured to be equal to.

Eratosthenes attempted to calculate its circumference by measuring the angle of the sun at two different locations.

Eratosthenes, who lived in Athens as a young man, claimed that Aristo and Arcesilaus were the two most important philosophers of his age.

< p > Strabo ... enters largely, in the Second Book of his Geography, into the opinions of Eratosthenes and other Greeks on one of the most difficult problems in geology, viz., by what causes marine shells came to be plentifully buried in the earth at such great elevations and distances from the sea .</ p >

In mathematics, the sieve of Eratosthenes (), one of a number of prime number sieves, is a simple, ancient algorithm for finding all prime numbers up to any given limit.

Many parts of modern geometry are based on the work of Euclid, while Eratosthenes was one of the first scientific geographers, calculating the circumference of the earth and conceiving the first maps based on scientific principles.

In 403 he came forward as the accuser of Eratosthenes, one of the Thirty Tyrants.

Most of these are purely geographical claims, but he does mention that Eratosthenes ' sources say that some of the Greek kings conquered further than Alexander ; Strabo does not believe them on this, but modern historians do ; nor does he believe that Menander and Demetrius son of Euthydemus conquered more tribes than Alexander There is half a story about Menander in one of the books of Polybius which has not come down to us intact.

About 150 years after the disaster, the philosopher Eratosthenes visited the site and reported that a standing bronze statue of Poseidon was submerged in a " poros ", " holding in one hand a hippocamp ", where it posed a hazard to those who fished with nets.

) to be purely legendary, many modern mathematicians and astronomers believe the description to be reasonable ( and believe Eratosthenes ' achievement to be one of the more impressive accomplishments of ancient astronomy ).

Strabo reports that Eratosthenes places Thule at a parallel 11500 stadia ( 1305 miles, or 16. 4 °) north of the mouth of the Borysthenes.

A statement of Eratosthenes attributed by Strabo to Pytheas, that the north of the Iberian Peninsula was an easier passage to Celtica than across the Ocean, is somewhat ambiguous: apparently he knew or knew of both routes, but he does not say which he took.

Strabo in his Geography ( c. 30 ), Book I, Chapter 4, mentions Thule in describing Eratosthenes ' calculation of " the breadth of the inhabited world " and notes that Pytheas says it " is a six days ' sail north of Britain, and is near the frozen sea.

It lies to the southwest of the much younger crater Eratosthenes, at the north edge of Mare Insularum where the mare joins Sinus Aestuum.

To the north is the Montes Apenninus range and the prominent crater Eratosthenes.

Herodotus, Strabo, and other classical authors repeatedly mention the Caspians but do not seem to know much about them ; they are grouped with other inhabitants of the southern shore of the Caspian Sea, like the Amardi, Anariacae, Cadusii, Albani ( see below ), and Vitii ( Eratosthenes apud Strabo, 11. 8. 8 ), and their land ( Caspiane ) is said to be part of Albania ( Theophanes Mytilenaeus apud Strabo, 11. 4. 5 ).

:" Accordingly, the Volcae Tectosages, seized on those parts of Germany which are the most fruitful lie around the Hercynian forest, ( which, I perceive, was known by report to Eratosthenes and some other Greeks, and which they call Orcynia ), and settled there.

During the Renaissance, printing of Catasterismi, invariably attributed to Eratosthenes, began early, but the work was always overshadowed by Hyginus, the only other ancient repertory of catasterisms.

As noted in the book Huai Nan Zu, in the 2nd Century BC Chinese astronomers effectively inverted Eratosthenes ' calculation of the curvature of the Earth to calculate the height of the sun above the earth.

The Earth's circumference was first determined around 240 BC by Eratosthenes.

Eratosthenes knew that in Syene, in Egypt, the Sun was directly overhead at the summer solstice, while he estimated that the angle formed by a shadow cast by the Sun at Alexandria was 1 / 50th of a circle.

Early in Classical Greece, that the earth is a sphere (" round "), was generally known by all, and around 240 BCE, Eratosthenes ( 276 BCE – 194 BCE ) accurately estimated its circumference.

A Sieve of Eratosthenes benchmark, computing all prime numbers less than 65536, was tested on a Sun SPARCstation 1.

* 1184 BC – Trojan War: Troy is sacked and burned, according to calculations by Eratosthenes.

These included notable thinkers such as Euclid, Archimedes, Eratosthenes, Herophilus, Erasistratus, Hipparchus, Aedesia, Pappus, Hypatia, Aristarchus of Samos, and Saint Catherine.

Eratosthenes the Cyrene was the first to divide the surface of the earth into lines of latitude and longitude.

In 1773, Lessing published an epigram he had found in a manuscript during his work as a librarian ; it claimed to be a letter sent by Archimedes to Eratosthenes.

Several works among the best known during this long period could be cited as an example, from Strabo ( Geography ), Eratosthenes ( Geography ) or Dionisio Periegetes ( Periegesis Oiceumene ) in the Ancient Age to the Alexander von Humboldt ( Cosmos ) in the century XIX, in which geography is regarded as a physical and natural science, of course, through the work Summa de Geografía of Martín Fernández de Enciso from the early sixteenth century, which is indicated for the first time the New World.

* Eratosthenes ( 276194 BC ), who made the first known reliable estimation of the Earth's size.

The early part of Pytheas ' voyage is outlined by statements of Eratosthenes that Strabo says are false because taken from Pytheas.

Eratosthenes extends the latitudinal distance from Massalia to Celtica to 5000 stadia ( 7. 1 °), placing the base line in Normandy.

On the surface it appears that Eratosthenes altered the base line to pass through the northern extreme of Celtica.

Maps based on scientific principles had been made since the time of Eratosthenes ( 3rd century BC ), but Ptolemy improved projections.

One reason is that Ptolemy estimated the size of the Earth as too small: while Eratosthenes found 700 stadia for a great circle degree on the globe, in the Geographia Ptolemy uses 500 stadia.

Book 34 was entirely devoted to questions of geography and included some trenchant criticisms of Eratosthenes, whom he accused of passing on popular preconceptions or laodogmatika.

Random access is critical, or at least valuable, to many algorithms such as binary search, integer sorting or certain versions of sieve of Eratosthenes.

Eratosthenes claimed it as the arrow with which Apollo exterminated the Cyclopes.

Those who believe that the stories of the Trojan War are derived from a specific historical conflict usually date it to the 12th or 11th centuries BC, often preferring the dates given by Eratosthenes, 1194 – 1184 BC, which roughly corresponds with archaeological evidence of a catastrophic burning of Troy VIIa.

Ephorus gives 1135 BC, Sosibius 1172 BC, Eratosthenes 1184 BC / 1183 BC, Timaeus 1193 BC, the Parian marble 1209 BC / 1208 BC, Dicaearchus 1212 BC, Herodotus around 1250 BC, Eretes 1291 BC, while Douris 1334 BC.