Talk:Eratosthenes

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Contents

[edit] (re)sources

You may want to check this passage from The Story of Geographical Discovery How the World Became Known by Joseph Jacobs, at []=112130 gutenberg. --MATIA 22:21, 30 August 2005 (UTC)

Two passages from John Lord:

By William Stevenson, A General History and Collection of Voyages and Travels - Volume 18

Williams, Edward Huntington, Williams, Henry Smith, History of Science, a — Volume 1

Apollonius Rhodius,

--MATIA 22:56, 30 August 2005 (UTC)


[edit] beta

ERATOSTHENES, "THE SURVEYOR OF THE WORLD" from Williams' A History of Science gutenberg 1hci10.txt

An altogether remarkable man was this native of Cyrene, who came to Alexandria from Athens to be the chief librarian of Ptolemy Euergetes. He was not merely an astronomer and a geographer, but a poet and grammarian as well. His contemporaries jestingly called him Beta the Second, because he was said through the universality of his attainments to be "a second Plato" in philosophy, "a second Thales" in astronomy, and so on throughout the list. He was also called the "surveyor of the world," in recognition of his services to geography. Hipparchus said of him, perhaps half jestingly, that he had studied astronomy as a geographer and geography as an astronomer. It is not quite clear whether the epigram was meant as compliment or as criticism...

Kerr's General History and Collection of Voyages and Travels gutenberg 13606-8

Ptolemy Euergetes was particularly attentive to the interests of the library at Alexandria. The first librarian appointed by Ptolemy the successor of Alexander, was Zenodotus; on his death, Ptolemy Euergetes invited from Athens Eratosthenes, a citizen of Cyrene, and entrusted to him the care of the library: it has been supposed that he was the second of that name, or of an inferior rank in learning and science, because he is sometimes called Beta; but by this appellation nothing else was meant, but that he was the second librarian of the royal library at Alexandria. He died at the age of 81, A.C. 194. He has been called a second Plato, the cosmographer and the geometer of the world: he is rather an astronomer and mathematician than a geographer, though geography is indebted to him for some improvements in its details, and more especially for helping to raise it to the accuracy and dignity of a science. By means of instruments, which Ptolemy erected in the museum at Alexandria, he ascertained the obliquity of the ecliptic to be 23° 51' 20". He is, however, principally celebrated as the first astronomer who measured a degree of a great circle, and thus approximated towards the real diameter of the earth. --MATIA 21:42, 5 September 2005 (UTC)


[edit] Measurement of the Earth

How did Erathothenes know that the Sun was very far away, in comparison to the size of the Earth? If you don't know that the Sun is far away, the observations can also be explained by a flat Earth and the Sun being close to the Earth (or a combination of the two). --Bubba73 (talk) 05:03, 4 October 2005 (UTC)

The moon is far away, by parallax. This rquires simultaneous observation at distant points; but simultaneity can be obtained by waiting for a lunat eclipse. The Sun is even further away (at half-moon, the triangle EMS has a right angle at M; the angle at E can be measured directly; the ratio of the two distances is the cosine of that angle.) --Septentrionalis 05:16, 4 October 2005 (UTC)
I assume that this was known at the time. Is that right? --Bubba73 (talk) 00:05, 23 October 2005 (UTC)
If I recall correctly, but I don't have a source in front of me; any history of Greek astronomy should do. --Septentrionalis 22:32, 23 October 2005 (UTC)

[edit] Time to remove the disputed tag?

Due to the finding of the arbitration commity (see Wikipedia:Requests_for_arbitration/Rktect#Remedies) there should be an opportunity to reach sufficient consensus so that the disputed tag can be removed. Anyone disagrees? --Egil 17:09, 22 October 2005 (UTC)

What is or was disputed? --Bubba73 (talk) 00:06, 23 October 2005 (UTC)
Afaik only contributions from Rktect, see Wikipedia:Requests_for_arbitration/Rktect/Evidence. I just want to make sure there is nothing else. -- Egil 00:35, 23 October 2005 (UTC)
Things appear to be adequate. Lose the tag already. --Mashford 19:58, 20 November 2005 (UTC)


[edit] cleanup and disputed

Well, someone had to do it... :) So I started. I think I've merged most new content, left some out. For instance:

"There are two theories concerning Plato's machine..."

because that's not related to Eratosthenes life at all (it's about doubling the cube which rktect was pushing) and because the latter part it's taken verbatim from another website (which is mentioned, but still it's copyvio). I could use some help to put in shape the earth's measurement section. I also removed the part taken verbatim from the math biographies page at the Erastothenes contributions section (for the same reasons outlined above) I finally took out the Strabo thing since I couldn't really understand its relevance (maybe on the entry of Strabo if there is one wold be more appropiated). --( drini's vandalproof page ☎ ) 17:03, 30 November 2005 (UTC)

[edit] Date of librarianship

When did Eratosthenes become the Library's head Librarian? This article says 236 BC, but I looked over at Britannica, and it says 255 BC- a pretty important difference. --maru (talk) Contribs 02:24, 6 January 2006 (UTC)

Lots of dates in antiquity are disputed or uncertain -- it'd take a bit of research to find out exactly what the possible range of dates is, which I don't have time to do just at the minute, but I can well believe it's uncertain to +/- 20 years or even more. In addition, ancient Greek dates are normally in the form "236/235 BCE" because the year ran from midsummer to midsummer. Petrouchka 11:10, 22 February 2006 (UTC)

[edit] Shape of Earth

Did Eratosthenes necessarily assume a spherical earth to make his math work? I always assume he did from my understanding. I assume also that Plato had a spherical earth in his philosophy because of the ideal of the sphere as perfect. Mike Logghe

Seems so likely that it's barely worth doubting, I'd suspect. AFAIK it's only in the last century or three that it's been known that the earth isn't spherical. Petrouchka 11:13, 22 February 2006 (UTC)

[edit] (1) Add a link to the famous map? (2) The map has a mystery

(I offer apologies in advance if i'm not adding my comment properly.)

(1) The article describes one of Erato's important contributions as, "A map of the entire known world". Such described map seems to be the map displayed at <http://en.wikipedia.org/wiki/Image:Iran.jpg#filelinks>; such displayed map is also shown at <http://en.wikipedia.org/wiki/Persia> and is there attributed to Erato. I don't know how to cite that link in the Erato article, so maybe someone else will do it. Thanks.

(2) The displayed map has words in English, such as "Northern Ocean". So Erato did not write such words on the map that is attributed to him. (Erato probably wrote Greek, I gather from the article.) So perhaps the English words were added centuries after Erato drew the map?? Bo99 23:11, 1 March 2006 (UTC)

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