The Greek astronomer Hipparchus ( c. 190 – c. 120 BCE ) credited Eratosthenes ( 276 – 194 BCE ) as the inventor of the armillary sphere.

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.

This possibility is likely, given that many ancient Greek philosophers are thought to have lived over the age of 90 ( e. g., Xenophanes of Colophon, c. 570 / 565 – c. 475 / 470 BC, Pyrrho of Ellis, c. 360 – c. 270 BC, Eratosthenes of Cirene, c. 285 – c. 190 BC, etc .).

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.

* c. 200 BC-the Sieve of Eratosthenes

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

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.

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

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.

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.

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.

* Eratosthenes 276 – 194 BC, ancient Greece

** Eratosthenes, Greek mathematician, geographer and astronomer ( b. 276 BC )

* Eratosthenes, Greek mathematician, geographer and astronomer ( b. 276 BC )

The Hellenistic world view after Seleucus: ancient world map of Eratosthenes ( 276 – 194 BC ), incorporating information from the campaigns of Alexander and his successors.

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

* 200 BC – Eratosthenes uses shadows to determine that the radius of the Earth is roughly 6, 400 km

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.

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.

240 BC – Eratosthenes measures the Earth's circumference and diameter

Because it is a simple extension of Eratosthenes ' idea, it is sometimes called the Legendre – Eratosthenes sieve.

Eratosthenes of Alexandria, who died about 194 BC, wrote on astronomy and geography, but his work is known mainly from later summaries.

* Eratosthenes, Greek mathematician, geographer and astronomer ( d. 194 BC )

Eratosthenes of Alexandria, who died about 194 BC, wrote on astronomy and geography, but his work is known mainly from later summaries.