Eratosthenes was the first to write on physical geography ; he also first attempted to draw up a chronological table of the Egyptian kings and of the historical events of Greece.

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 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.

Pliny claims that this gave Eratosthenes the idea about how to calculate the circumference of the Earth ( N. H. 2. 183, 6. 168 ).

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.

He defines the western coast-line of Spain and Gaul and its indentation by the Bay of Biscay more accurately than Eratosthenes or Strabo, his ideas of the British Isles and their position are also clearer than his predecessors.

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

* Eratosthenes: calculated the size of the earth and its distance to the sun and to the moon

However, the astrological connoisseurship of its fables in fact have nothing to do with Eratosthenes ' scientific conjectures and solutions — which belong instead near the origins of an astronomy that was separated from the predictive and interpretive functions of astrology, not an easy feat of the logical imagination.

The founder of the mathematical school was the celebrated Euclid ; among its scholars were Archimedes ; Apollonius of Perga, author of a treatise on Conic Sections ; Eratosthenes, to whom we owe the first measurement of the earth ; and Hipparchus, the founder of the epicyclical theory of the heavens, afterwards called the Ptolemaic system, from its most famous expositor, Claudius Ptolemy.

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

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.

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.

* 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.

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

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 ).

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.

Eratosthenes calculated the earth's circumference with remarkable accuracy, and Hipparchus Founded scientific astronomy.

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.

Many sources claim that the fabled Well of Erastothenes, famous for the calculation of the circumference of Earth by Eratosthenes, was located on the island.

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

Eratosthenes of Cyrene ( 276-196 BC ) deduced the circumference of the earth with remarkable accuracy.

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

This book is the original source for the well-known story of how Eratosthenes measured the Earth's circumference.

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.

* 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.

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.

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.

< 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 >

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.

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

* 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.

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.

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.

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

Using this measuring instrument Eratosthenes of Cyrene ( ca.