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.

The first known grade measurement was performed by Eratosthenes ( 240 BC ) between Alexandria and Syene in what is now Egypt, determining the radius of the Earth with remarkable correctness.

* c. 240 BCE Eratosthenes of Alexandria, Egypt determines fairly accurately the circumference of the Earth using angles of shadows in Syene and Alexandria.

Conversely, the remarkably accurate calculation of the earth's circumference by Eratosthenes, and the invention of a steam engine by Heron, both ascribed in chapter 60 to the priest Menes, historically occurred in Alexandrian Egypt, centuries after the period of the novel.

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

* The first good measurement of the distance between Earth and the Sun is made by Eratosthenes ( approximate date ).

When the Sun is directly overhead, however, Eratosthenes visually blends into the surroundings, and it becomes more difficult for an observer to locate it.

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

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

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.

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

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.

Although Strabo cited the antique Greek astronomers Eratosthenes and Hipparchus, acknowledging their astronomical and mathematical efforts towards geography, he claimed that a descriptive approach was more practical, such that his works were designed for statesmen who were more anthropologically than numerically concerned with the character of countries and regions.

That alternative route, different from the theoretical eastward route, was based on calculations of the Earth's circumference made by Columbus which showed the measurement to be substantially less than the classic 10, 000 mile figure given by Eratosthenes in the 3rd century BC.

The Portuguese Court, which agreed with the figure provided by Eratosthenes, rejected Columbus ' proposal because they believed that the distance to Asia over the open Western Ocean was too great for the ship's crews to survive the journey without being able to make port and resupply.

Cyrene was the birthplace of Eratosthenes and there are a number of philosophers associated with the city including Aristippus, the founder of the School of Cyrene, and his successor daughter Arete, Callimachus, Carneades, Ptolemais of Cyrene, and Synesius, a bishop of Ptolemais in the 4th century AD.

Posidonius was celebrated as a polymath throughout the Graeco-Roman world because he came near to mastering all the knowledge of his time, similar to Aristotle and Eratosthenes.

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 ).

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.

De Astronomia was first published, with accompanying figures, by Erhard Ratdolt in Venice, 1482, under the title Clarissimi uiri Hyginii Poeticon astronomicon opus utilissimum This " Poetic astronomy by the most renowned Hyginus, a most useful work ," chiefly tells us the myths connected with the constellations, in versions that are chiefly based on Catasterismi, a work that was traditionally attributed to Eratosthenes.

The first scientific estimation of the radius of the earth was given by Eratosthenes.

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.

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.

The general views of the De situ orbis mainly agree with those current among Greek writers from Eratosthenes to Strabo ; the latter was probably unknown to Mela.

It was notable for its famous librarians: Demetrius, Zenodotus, Eratosthenes, Apollonius, Aristophanes, Aristarchus, and Callimachus.

1241 indicates that Apollonius was succeeded in the position by Eratosthenes ; this must have been after 247 / 246 BCE, the date of the accession of Ptolemy III Euergetes, who was probably tutored by Apollonius and who appointed Eratosthenes.

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

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

< 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 >

Eratosthenes, using the angles of shadows created at widely separated regions, estimated the circumference of the Earth with great accuracy.

Eratosthenes and Apollodorus of Athens, however, pushed back the start of the historical period to the Trojan War, which they fixed at 1184 BC.

He succeeded Eratosthenes as head librarian of the Library of Alexandria at the age of sixty.

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

The land that became known as Khorasan in geography of Eratosthenes was recognized as Ariana at that time, which made up Greater Iran or the land where Zoroastrianism was the dominant religion.

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

The work survives in an epitome assembled at the end of the 1st century CE, based on a lost original, with a possible relation to work of Eratosthenes that is now hard to pinpoint ; thus the author is alluded to as Pseudo-Eratosthenes.

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.

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.

* The Hellenistic period Mathematician Eratosthenes estimated the radius of Earth's circumference to be 252, 000 Stadia, a figure between 2 %- 20 % off modern measurements.

His Indian conceptions are inferior to those of some earlier Greek writers ; he follows Eratosthenes in supposing that country to occupy the south-eastern angle of Asia, whence the coast trended northwards to Scythia, and then swept round westward to the Caspian Sea.

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

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.

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

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.

* Eratosthenes is appointed by King Ptolemy III Euergetes as head and third librarian of the Alexandrian library.

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

Since the estimate by Eratosthenes, many models have been created.

For this method, it is also necessary to check for divisibility by all primes that are less than c. Observations analogous to the preceding can be applied recursively, giving the Sieve of Eratosthenes.