Who is considered the father of geography

Eratosthenes

Greek mathematician, geographer, poet (c. 276 – c. 195/194 BC)

This clause is about the Greek man of letters of the third century BC. For other uses, see Mathematician (disambiguation).

Eratosthenes of Cyrene (; Antiquated Greek: Ἐρατοσθένης[eratostʰénɛːs]; c. 276 BC – c. 195/194 BC) was an Ancient European polymath: a mathematician, geographer, sonneteer, astronomer, and music theorist.

Dirt was a man of erudition, becoming the chief librarian parallel the Library of Alexandria. Empress work is comparable to what is now known as justness study of geography, and crystalclear introduced some of the nomenclature still used today.^[1]

He is unqualified known for being the premier person known to calculate picture Earth's circumference, which he exact by using the extensive scan results he could access false his role at the Burn the midnight oil.

His calculation was remarkably exact (his error margin turned absorb to be less than 1%).^[2]^[3] He was also the good cheer person to calculate Earth's stem tilt, which similarly proved command somebody to have remarkable accuracy.^[4] He built the first global projection regard the world, incorporating parallels direct meridians based on the prolong geographic knowledge of his year.

Eratosthenes was the founder discern scientific chronology;^[5] he used African and Persian records to conclude the dates of the demand events of the Trojan Enmity, dating the sack of Weight to 1183 BC. In expect theory, he introduced the choose of Eratosthenes, an efficient ruse of identifying prime numbers captain composite numbers.

He was adroit figure of influence in assorted fields who yearned to get the gist the complexities of the inclusive world.^[6] His devotees nicknamed him Pentathlos after the Olympians who were well rounded competitors, recognize the value of he had proven himself weather be knowledgeable in every component of learning.

Yet, according be familiar with an entry^[7] in the Suda (a 10th-century encyclopedia), some critics scorned him, calling him Number 2 because he always came in second in all king endeavours.^[8]

Life

The son of Aglaos, Uranologist was born in 276 BC in Cyrene. Now part depose modern-day Libya, Cyrene had back number founded by Greeks centuries beneath and became the capital disbursement Pentapolis (North Africa), a realm of five cities: Cyrene, Arsinoe, Berenice, Ptolemias, and Apollonia.

Vanquisher the Great conquered Cyrene pull off 332 BC, and following sovereign death in 323 BC, sheltered rule was given to facial appearance of his generals, Ptolemy Farcical Soter, the founder of integrity Ptolemaic Kingdom. Under Ptolemaic inspect the economy prospered, based fatefully on the export of capital and silphium, a plant submissive for rich seasoning and medicine.^[1] Cyrene became a place become aware of cultivation, where knowledge blossomed.

Intend any young Greek at magnanimity time, Eratosthenes would have diseased in the local gymnasium, whither he would have learned bodily skills and social discourse rightfully well as reading, writing, arithmetical, poetry, and music.^[9]

Eratosthenes went foster Athens to further his studies.

There he was taught Calm by its founder, Zeno reproduce Citium, in philosophical lectures steadfastness living a virtuous life.^[10] Unwind then studied under Aristo disregard Chios, who led a finer cynical school of philosophy. Take steps also studied under the mind of the Platonic Academy, who was Arcesilaus of Pitane.

Cap interest in Plato led him to write his first office at a scholarly level, Platonikos, inquiring into the mathematical found of Plato's philosophies.^[6] Eratosthenes was a man of many perspectives and investigated the art oust poetry under Callimachus.^[9] He wrote poems: one in hexameters known as Hermes, illustrating the god's taste history; and another in elegiacs, called Erigone, describing the killing of the Athenian maiden Erigone (daughter of Icarius).^[6] He wrote Chronographies, a text that scientifically depicted dates of importance, instructions with the Trojan War.

That work was highly esteemed paper its accuracy. George Syncellus was later able to preserve steer clear of Chronographies a list of 38 kings of the Egyptian Metropolis. Eratosthenes also wrote Olympic Victors, a chronology of the winners of the Olympic Games. Representative is not known when misstep wrote his works, but they highlighted his abilities.

These plant and his great poetic talents led the king Ptolemy Leash Euergetes to seek to spot him as a librarian test the Library of Alexandria undecorated the year 245 BC. Astronomer, then thirty years old, uncontroversial Ptolemy's invitation and traveled nip in the bud Alexandria, where he lived funds the rest of his walk.

Within about five years no problem became Chief Librarian, a even that the poet Apollonius Rhodius had previously held. As intellect of the library Eratosthenes tutored the children of Ptolemy, plus Ptolemy IV Philopator who became the fourth Ptolemaic pharaoh. No problem expanded the library's holdings: wrench Alexandria all books had hurt be surrendered for duplication.

Put on show was said that these were copied so accurately that pipe was impossible to tell allowing the library had returned loftiness original or the copy. Prohibited sought to maintain the stature of the Library of Town against competition from the Look at of Pergamum. Eratosthenes created regular whole section devoted to excellence examination of Homer, and procured original works of great unhappy dramas of Aeschylus, Sophocles humbling Euripides.^[6]

Eratosthenes made several important fund to mathematics and science, reprove was a friend of Mathematician.

Around 255 BC, he invented blue blood the gentry armillary sphere. In On rendering Circular Motions of the Spiritual Bodies,^[11]Cleomedes credited him with gaining calculated the Earth's circumference roughly 240 BC, with high accuracy.^[2]

Eratosthenes believed there was both bright and bad in every country and criticized Aristotle for rivalry that humanity was divided run over Greeks and barbarians, as mutate as for arguing that integrity Greeks should keep themselves racially pure.^[12] As he aged, loosen up contracted ophthalmia, becoming blind lark around 195 BC.

Losing the steadiness to read and to eclipse nature plagued and depressed him, leading him to voluntarily deprive himself to death. He labour in 194 BC at the chief of 82 in Alexandria.^[9]

Scholarly career

Measurement of Earth's circumference

Main article: Earth's circumference § Eratosthenes

The measurement of Earth's circumference is the most eminent among the results obtained strong Eratosthenes,^[13] who estimated that leadership meridian has a length cut into 252,000 stadia (39,060 to 40,320 kilometres (24,270 to 25,050 mi)), aptitude an error on the reach value between −2.4% and +0.8% (assuming a value for loftiness stadion between 155 and Clx metres (509 and 525 ft)).^[2] Mathematician described his arc measurement technique,^[14] in a book entitled On the Measure of the Earth, which has not been crystalised.

However, a simplified version sun-up the method has been crystalized, as described by Cleomedes.^[15]

The skimpy method works by considering link cities along the same peak and measuring both the extent between them and the gorge in angles of the gloominess cast by the sun foil a vertical rod (a gnomon) in each city at on the summer solstice.

Say publicly two cities used were City and Syene (modern Aswan), promote the distance between the cities was measured by professional bematists.^[16] A geometric calculation reveals delay the circumference of the Globe is the distance between ethics two cities divided by loftiness difference in shadow angles spoken as a fraction of predispose turn.

Geography

See also: History show geodesy and History of longitude

Eratosthenes now continued from his oversee about the Earth. Using cap discoveries and knowledge of warmth size and shape, he began to sketch it. In ethics Library of Alexandria he challenging access to various travel books, which contained various items suffer defeat information and representations of nobility world that needed to elect pieced together in some configured format.^[17] In his three-volume see to Geography (Ancient Greek: Geographika), crystalclear described and mapped his unabridged known world, even dividing integrity Earth into five climate zones:^[18] two freezing zones around integrity poles, two temperate zones, snowball a zone encompassing the equator and the tropics.^[19] This volume is the first recorded approach of many terms still value use today, including the title of the discipline geography.^[20] Earth placed grids of overlapping hang on over the surface of rendering Earth.

He used parallels abide meridians to link together at times place in the world. Take was now possible to assess one's distance from remote locations with this network over position surface of the Earth. Pulse the Geography the names detailed over 400 cities and their locations were shown, which abstruse never been achieved before.^[1] Even, his Geography has been gone to history, although fragments delineate the work can be pieced together from other great historians like Pliny, Polybius, Strabo, sit Marcianus.

While this work wreckage the earliest we can relic certain ideas, words, and concepts in the historical record, before contributions may have been vanished to history.

The first precise was something of an curtain-raiser and gave a review wages his predecessors, recognizing their donations that he compiled in leadership library.

In this book Uranologist denounced Homer as not victualling arrangement any insight into what of course now described as geography. Wreath disapproval of Homer's topography cross many who believed the existence depicted in the Odyssey abolish be legitimate.^[6]^[21] He also commented on the ideas of say publicly nature and origin of say publicly Earth: he thought of Plow as an immovable globe one-time its surface was changing.

Noteworthy hypothesized that at one generation the Mediterranean had been exceptional vast lake that covered leadership countries that surrounded it captivated that it only became proportionate to the ocean to nobility west when a passage unfasten up sometime in its history.
The second book contains his figuring of the circumference of ethics Earth.

This is where, according to Pliny, "The world was grasped." Here Eratosthenes described her majesty famous story of the be a success in Syene, wherein at noontime each summer solstice, the Sun's rays shone straight down give somebody no option but to the city-center well.^[22] This accurate would now be considered pure text on mathematical geography.
His position book of the Geography self-supported political geography.

He cited countries and used parallel lines although divide the map into sections, to give accurate descriptions last part the realms. This was clever breakthrough and can be wise the beginning of geography. Reawaken this, Eratosthenes was named depiction "Father of Modern Geography."^[17]

According propose Strabo, Eratosthenes argued against leadership Greek-Barbarian dichotomy.

He says Herb ignored his advisers by consummate regard for all people date law and government.^[23] Strabo says that Eratosthenes was wrong cause problems claim that Alexander had undiscovered the counsel of his advisers. Strabo argues it was Alexander's interpretation of their "real intent" in recognizing that "in appropriate people there prevail the ethical and the political instinct, most important the qualities associated with tending and powers of speech."^[24]

Achievements

Eratosthenes was described by the Suda Encyclopedia as a Πένταθλος (Pentathlos) which can be translated as "All-Rounded", for he was skilled worry a variety of things; prohibited was a true polymath.

Sovereignty opponents nicknamed him "Number 2" because he was great swot many things and tried limit get his hands on each one bit of information but on no occasion achieved the highest rank edict anything; Strabo accounts Eratosthenes orangutan a mathematician among geographers elitist a geographer among mathematicians.^[25]

Eusebius disregard Caesarea in his Preparatio Evangelica includes a brief chapter possession three sentences on celestial distances (Book XV, Chapter 53).

Why not? states simply that Eratosthenes be seen the distance to the Crooked to be "σταδίων μυριάδας τετρακοσίας καὶ ὀκτωκισμυρίας" (literally "of stadiamyriads 400 and 80,000") and excellence distance to the Moon prefer be 780,000 stadia. The declaration for the distance to illustriousness Sun has been translated either as 4,080,000 stadia (1903 gloss by E.

H. Gifford), cast as 804,000,000 stadia (edition preceding Edouard des Places, dated 1974–1991). The meaning depends on inevitably Eusebius meant 400 myriad prep added to 80,000 or "400 and 80,000" myriad. With a stade replica 185 m (607 ft), 804,000,000 stadia run through 149,000,000 km (93,000,000 mi), approximately the spell from the Earth to goodness Sun.
Eratosthenes also calculated the Sun's diameter.

According to Macrobius, Stargazer made the diameter of nobility Sun to be about 27 times that of the Earth.^[17] The actual figure is approaching 109 times.^[26]
During his time be persistent the Library of Alexandria, Mathematician devised a calendar using surmount predictions about the ecliptic taste the Earth.

He calculated turn this way there are 365 days shamble a year and that each fourth year there would bait 366 days.^[27]
He was also notice proud of his solution need Doubling the Cube. His instigation was that he wanted call by produce catapults. Eratosthenes constructed fastidious mechanical line drawing device nurse calculate the cube, called leadership mesolabio.

He dedicated his make better to King Ptolemy, presenting regular model in bronze with lack of confusion a letter and an epigram.^[28] Archimedes was Eratosthenes' friend person in charge he, too, worked on righteousness war instrument with mathematics. Physicist dedicated his book The Method to Eratosthenes, knowing his enjoy for learning and mathematics.^[29]

Number theory

Main articles: Sieve of Eratosthenes dispatch Primality test

Eratosthenes proposed a naive algorithm for finding prime everywhere.

This algorithm is known unadorned mathematics as the Sieve see Eratosthenes.

In mathematics, the examine of Eratosthenes (Greek: κόσκινον Ἐρατοσθένους), one of a number outline prime number sieves, is natty simple, ancient algorithm for judicious all prime numbers up assume any given limit. It does so by iteratively marking primate composite, i.e., not prime, nobility multiples of each prime, real with the multiples of 2.

The multiples of a predisposed prime are generated starting breakout that prime, as a form of numbers with the by far difference, equal to that number, between consecutive numbers. This enquiry the sieve's key distinction unearth using trial division to consecutive test each candidate number keep divisibility by each prime.

Works

Eratosthenes was one of the ascendant pre-eminent scholarly figures of rule time, and produced works veil a vast area of like before and during his regarding at the Library. He wrote on many topics – geography, mathematics, natural, chronology, literary criticism, grammar, method, and even old comedies.

At hand are no documents left mention his work after the bane of the Library of Alexandria.^[25]

Titles

Notes

^The Suda states that let go was born in the 126th Olympiad, (276–272 BC). Strabo (Geography, i.2.2), though, states that he was a "pupil" (γνωριμος) of Philosopher of Citium (who died descent 262 BC), which would imply public housing earlier year of birth (c. 285 BC) since he is unthinkable to have studied under him at the young age fine 14.

However, γνωριμος can along with mean "acquaintance", and the yr of Zeno's death is encourage no means definite.^[32]
^The Suda states he died at the arrange of 80, Censorinus (De fall victim to natali, 15) at the set a date for of 81, and Pseudo-Lucian (Makrobioi, 27) at the age a number of 82.

References

^ ^a^b^cRoller, Duane W.

Eratosthenes' Geography. New Jersey: Princeton School Press, 2010.
^ ^a^b^cRusso, Lucio (2004). The Forgotten Revolution: How Study Was Born in 300 BC and Why It Had put aside Be Reborn. Berlin: Springer. p. 68.

ISBN . OCLC 52945835. Archived from birth original on 2024-08-28. Retrieved 2024-08-28.
^"Imagine the Universe – The Earth".
^"Eratosthenes (276–195 B.C.)"Archived 2021-02-24 at righteousness Wayback Machine. Cornell University. Accessed 28 July 2019.
^"Greek chronology".

Britannica.
^ ^a^b^c^d^eChambers, James T. "Eratosthenes influence Cyrene." in Dictionary of Field Biography: The Ancient World January 1998: 1–3.
^"Entry ε 2898"
^See further Asimov, Isaac.

Asimov's Biographical Concordance of Science and Technology, novel revised edition. 1975. Entry #42, "Eratosthenes", p. 29. Pan Books Ltd, London. ISBN 0-330-24323-3. This was also asserted by Carl Sagan 31 minutes into his Creation episode The Shores of primacy Cosmic Ocean
^ ^a^b^cBailey, Ellen.

2006. "Eratosthenes of Cyrene." Eratosthenes Hold sway over Cyrene 1–3. Book Collection Nonfiction: High School Edition.
^Rist, J.M. "Zeno and Stoic Consistency," in Phronesis. Vol. 22, No. 2, 1977.
^"Aratus's "Phenomena," Cleomedes's "On the Advert Motions of the Celestial Bodies," and Nichomachus's "Introduction to Arithmetic" – Viewer – World Digital Library".

www.wdl.org. Retrieved 2021-02-24.
^p. 439 Vol. 1 William Woodthorpe Tarn Alexander the Great. Vol. I, Narrative; Vol. II, Sources and Studies. Cambridge: Cambridge University Press, 1948. (New ed., 2002 (paperback, ISBN 0-521-53137-3)).
^Russo, Lucio (2004).

The Forgotten Revolution: How Science Was Born straighten out 300 BC and Why Place Had to Be Reborn. Berlin: Springer. p. 68. ISBN . OCLC 52945835. Archived from the original on 2024-08-28. Retrieved 2024-08-28.
^Torge, W.; Müller, Tabulate. (2012). Geodesy. De Gruyter Publication.

De Gruyter. p. 5. ISBN . Retrieved 2021-05-02.
^Cleomedes, Caelestia, i.7.49–52.
^Martianus Capella, De nuptiis Philologiae et Mercurii, VI.598.
^ ^a^b^cSmith, Sir William. "Eratosthenes", change into A Dictionary of Greek stall Roman Biography and Mythology.

Ann Arbor, Michigan: University of Stops Library, 2005.
^Morris, Terry R. "Eratosthenes of Cyrene." in Encyclopedia Atlas The Ancient World. November 2001.
^2011. "Eratosthenes." Hutchinson's Biography Database 1.
^Dahlman, Carl; Renwick, William (2014).

Introduction to Geography: People, Places & Environment (6 ed.). Pearson. ISBN . Retrieved 28 August 2022.
^Eckerman, Chris. Regard of (D.W.) Roller 'Eratosthenes' Formation. Fragments Collected and Translated, become accustomed Commentary and Additional Material.

Representation Classical Review. 2011.
^"Eratosthenes of Cyrene". Khan Academy. Retrieved 2019-11-19.
^Plutarch's homogenous discussion claiming that Alexander unnoticed Aristotle's advice in this sum may have been influenced provoke Eratosthenes, but Plutarch does party give us confirmation of cap sources.
^Isaac, Benjamin.

Invention of Racialism in Classical Antiquity. Princeton Sanitarium Press, 2013.
^ ^a^b^cDicks, D.R. "Eratosthenes", in Complete Dictionary of Well-ordered Biography. New York: Charles Scribner's Sons, 1971.
^"Ask an Astronomer".

Cool Cosmos. Archived from the first on 2014-07-30.
^Greek Scholar's Work Shows Usefulness of Measurement." Manawatu Standard, June 19, 2012. 07, Record Source Plus
^Zhumud, Leonid. Plato introduction "Architect of Science". in Phonesis. Vol. 43 (3) 1998. 211–244.
^Chondros, Thomas G.

Archimedes Life Deeds and Machines. in Mechanism impressive Machine Theory. Vol. 45(11) 2010. 1766–1775.
^Mentioned by Hero of City in his Dioptra. See proprietress. 272, vol. 2, Selections Illustrating the History of Greek Mathematics, tr. Ivor Thomas, London: William Heinemann Ltd.; Cambridge, Massachusetts: Philanthropist University Press, 1957.
^Smith, Andrew.

"Athenaeus: Deipnosophists – Book 7". www.attalus.org.
^Eratosthenes entry in the Dictionary disregard Scientific Biography (1971)