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- 1 Jenny
- 2 baffling section '...Alexandria lighthouse...large earth radius...small AU
- 3 (re)sources
- 4 Measurement of the Earth
- 5 Time to remove the disputed tag?
- 6 cleanup and disputed
- 7 Date of librarianship
- 8 Shape of Earth
- 9 (1) Add a link to the famous map? (2) The map has a mystery
- 10 A drawing would help
- 11 "He also made what he thought was a map of the Earth."
- 12 Fleet of Circumnavigation
- 13 One question about measurement of the Earth
- 14 5000
- 15 Sieve of Eratosthenes
- 16 Herodotus
- 17 Birth date
- 18 Eratosthenes and the Alexandria lighthouse ...
- 19 Zombie Eratosthenes?
- 20 Pronunciation of the name (stress placement)
- 21 Collaborative projects
- 22 Point of the portrait?
- 23 Citation request
- 24 Capital of Ptolemaic Egypt?
- 25 Note
- 26 Earth measurement information
- 27 Improper Citation
- 28 Computer Scientist?
- 29 Formula
- 30 History of Science Edits
- 31 Berber Origines
I think the article is really good. I'm not sure what all you added but there is so much about this guy to know. The only thing I can think to ask is was he ever married or have any kids? Is there anything more to know about his life that didn't have anything to do with his profession? — Preceding unsigned comment added by Kycarp20 (talk • contribs) 21:32, 13 November 2013 (UTC)
Hey Jenny, the last sentence of the third paragraph in the "Life" section may need to be looked at. You could possibly reword it to say something like "As head of the library, Eratosthenes had many tasks that he was required to do such as...". There also seems to be an Oxford Reference problem in that section but I'm not sure if that is related to you. In the "Geography" section, you might shorten the third sentence by making it two sentences. You might also make a link to Geographika. Bill Nye OU (talk) 21:34, 17 November 2013 (UTC)
baffling section '...Alexandria lighthouse...large earth radius...small AU
The two paragraphs under this heading are a baffling non sequitur as they don't give any context. The article is clear and readable up to this point. I have no idea who Eusebius is, it's not clear why we're talking about lighthouses, a mass of measurements and percentages are introduced, and the tone changes from being supportive of Erastothenes to criticising him. The lighthouse story sounds interesting, but the detailed arguments over numbers are perhaps best left to the academic papers outside Wikipedia. --Air (talk) 14:13, 18 May 2009 (UTC)
- You are quite right, Air. The two disjointed paragraphs were added by 188.8.131.52 on 30/10/2008. — Preceding unsigned comment added by 184.108.40.206 (talk) 14:24, 25 November 2011 (UTC)
Two passages from John Lord:
- =42620 http://www.gutenberg.org/catalog/world/fulltext-context?fulltext=eratosthenes&fk_files=42620
- =11535 http://www.gutenberg.org/catalog/world/fulltext-context?fulltext=eratosthenes&fk_files=11535
By William Stevenson, A General History and Collection of Voyages and Travels - Volume 18
- =99196 http://www.gutenberg.org/catalog/world/fulltext-context?fulltext=eratosthenes&fk_files=99196
Williams, Edward Huntington, Williams, Henry Smith, History of Science, a — Volume 1
- =38860 http://www.gutenberg.org/catalog/world/fulltext-context?fulltext=eratosthenes&fk_files=38860
- =36838 http://www.gutenberg.org/catalog/world/fulltext-context?fulltext=eratosthenes&fk_files=36838
--MATIA 22:56, 30 August 2005 (UTC)
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 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)
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)
- 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)
- Yes, I'm sure I've read that the Greeks tried to determine the ES-to-EM distance ratio, and got it wrong on the short side by a factor of about 5 or 10, the difficulty being in accurately identifying exact first-quarter phase, and in measuring the slight difference between the MES angle and 90 degrees. (The actual distance ratio is just about 400). They did, however, by this means, find that the Sun was many times more distant than the moon. --Fredgds (talk) 06:39, 29 December 2009 (UTC)
Sorry to say this, but mathematically, Eratosthenes did not really proof that the earth was not flat, but like a ball. Because in his "evidence" he assumed that the rays, which come from the sun, are parallel. If I were a solicitor of the ancient Greek world view, I could say that the rays needn ´t be parallel. The sun can also be round (as a solicitor of the ancient Greek view of the world, I would only have to defend the thesis that the earth is flat). So the sun rays can also be anti-parallel. But then the earth can be flat and it is no contradiction, if the stick of Eratosthenes cast a cloud in Syene, but not in Alexandria during the same time.
If you put 2 pens on a desk and an electric light bulb exactly over 1 pen, then this pen will surely not cast a cloud, but the other pen, which is not directly over the light bulb, does.
So Eratosthenes did not give an evidence. If one argued that then the sun would then be too close to the earth (because the distance sun earth can be measured with the sentence of Pythagoras) and therefor the earth would be burnt, one could say (as a solicitor of the ancient Greek view of the world) that nobody knows how hot the sun is and via the Gods, like Zeus the hot rays of the sun are cooled :-).
However, Eratosthenes did not give any mathematical evidences of the earth of being round and no evidences of the length of the equator. —The preceding unsigned comment was added by 220.127.116.11 (talk) 14:58, 25 April 2007 (UTC).
- This contention (that Eratosthenes didn't really prove the Earth not to be flat) is refuted by the Greeks' knowledge at that time that the Sun was much more distant than the moon (based on the very nearly right-angle separation of the two bodies at half-moon phases), which in turn was known (by parallax; star backgrounds seen from widely separated places during the same lunar eclipse) to be many times more distant than, say, the Alexandria-Syene distance. (This is pointed out above, in a little less detail, by Septentrionalis.) So it was known that the Sun's rays in those two places were virtually parallel. --Fredgds (talk) 06:39, 29 December 2009 (UTC)
My understanding is that a spherical Earth was the accepted opinion among Greek scientists. Eratosthenes was therefore not concerned with proving that the Earth was not flat, he was merely attempting to measure it. 18.104.22.168
- The Greeks knew. By looking at their ports and out to sea one can easy notice that the earth is not flat (by the way ships disapear). --Firebird 01:14, 16 October 2007 (UTC)
- They also considered the roundness of Earth's shadow on the moon during every lunar eclipse as evidence of a spherical Earth. I believe the progressive disappearance of ships' masts as they sailed out was cited by Galileo? Don't know whether he had learned of this line of evidence from ancient Greece? Perhaps someone can answer whether the Greeks in fact used this argument for a round Earth. I believe Firebird is correct on this. --Fredgds (talk) 06:39, 29 December 2009 (UTC)
I think the part about the sun appearing as disk, as opposed to a point, is rather irrelevant. A disk is fine, as you can simply measure based on the center of it. So just saying that the sun is not infinitely far away is sufficient.--Robbrown 05:04, 2 August 2007 (UTC)
- Furthermore, it's not particularly difficult to measure the angular size of the sun's disk (about 1/2 degree), so that can be accounted for in any angular measure of the shadow. Never assume these people were stupid.
- True, they were far from stupid, but it's not really that easy. What the Sun's non-point nature does is to blur out the shadow of a point object, making it difficult to locate its center. In that era they could have determined the shadow location better than the +/- 1/4 degree imposed by the size of the blur, but not by a whole lot. Still, if done carefully, maybe they could get the location to within +/-0.1 deg, and this should introduce only a few percent error in the result -- based on use of a great-circle arc of 7.5 degrees. --Fredgds (talk) 06:39, 29 December 2009 (UTC)
- Fred Hoyle, a recently deceased and well-respected astronomer, points out that the distances in ancient Egypt were fairly well known. Runners were used to carry messages between cities and they had, over time, developed the knowledge of the distances to a fair level of accuracy - about 1%. The Itinerary stadia is suitable for runners' distances and since it gives an error for the size of the Earth (IIRC) of about 4%, Hoyle argues, reasonably IMNSHO, that Eratosthenes "got-it-right".
- I think the section should be changed to be more neutral, with a proper discussion of the interpretation of his work. It currently reeks of POV. Michael Daly 21:23, 13 September 2007 (UTC)
There can be no justification for having a "citation needed" that the Sun appears as disk for goodness sake. It might be argued that he could judge the centre of the sun anyway but if you leave the text in it just makes a mockery of the article to ask for a citation. Similarly with the "citation needed" for distances not being accurate in this period. Most people would be hard pressed to measure a distance over several miles to better than 1% even today. To say this needs citing is plain stupid. You'll be asking for a citation that the world exists at all next.
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)
- 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)
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)
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)
- Also, the article says "In 236 BC he was appointed by Ptolemy III Euergetes as librarian of the Alexandrian library, succeeding the second librarian, Apollonius of Rhodes," but the Library of Alexandria article lists Apollonius as the third librarian (after Zenodotus and Callimachus), with Eratosthenes fourth. Can someone more knowledgeable than I correct the discrepancy in one place or the other? Dodiad (talk) 20:52, 29 November 2012 (UTC)
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)
- I have reverted the claim made in the antecedent edit, which appears to be original research.
- (dubious claim removed - it is impossible to prove the Earth is round while staying around one point on its surface. It COULD be HALF a sphere for all he knew. It was his ASSUMPTION, under which he derived the circumference value.)
- This is wrong. I am an astronomer and have taught this subject for over 40 years. It is well known that you CAN prove that the Earth is round while staying around one point on its surface. The reason is that lunar eclipses can take place at any position in the sky. If the Earth were hemispherical, for example, at some positions of the eclipse you will see a round shadow at ingress and a straight shadow at egress (or vice versa). This will happen whenever the eclipse takes place near the horizon. Similarly, a flat Earth would produce straight shadows at both ingress and egress when the eclipse takes place near the horizon. Only a spherical shape produces curved shadows (of constant or near constant curvature) regardless of the position of the Moon at the eclipse. This is explained in numerous elementary astronomy texts. This fact was known to the ancients. I'm pretty sure we mentioned it in my own text, Discovering Astronomy (Jefferys and Robbins, mid-70s. I'm sitting at the car dealer right now and don't have the exact reference available). Bill Jefferys (talk) 13:37, 17 June 2011 (UTC)
- great, so is THIS what Eratosthenes did to prove it? How do we know? The claim in the article, which you so valiantly restored, gives us no source nor citation - nothing. How's THAT for the original research! And btw, OR only pertains to the article contents, not some remarks on history lists, is it not?
- so if there's no evidence or citation for Eratosthenes actually doing what is claimed there, I think that OR claim in the text of the article about him proving it, however it may seem likely to you and now me also that he understood it, should be removed. Would you agree? WillNess (talk) 19:05, 18 June 2011 (UTC)
- My reversion of your removal was based on your incorrect claim that the shape of the Earth cannot be inferred from observations made from one point on the Earth's surface, and not from the lack of a citation, which you didn't mention. I agree, the lack of a citation is a problem that needs to be fixed.
- I do not know what sources, if any, that the person who originally posted this claim was using. (I am not that person). I presume that that individual had some source in mind for this claim. But it is not given; a request for a citation is already in the article. I would agree with you that if, within a reasonable period of time (now that this is the issue), no citation is forthcoming, then removal of this claim would be appropriate. But sufficient time should elapse until that action is taken, from the time that it has become evident that it is an issue (that is to say, from now).
- By the way, there is no need to be nasty or sarcastic. WikiPedia is a cooperative adventure, and snide comments do not promote its ends. Simply state the facts as you know them.
- My guess is that the spherical shape of the Earth was well known long before Eratosthenes made his measurement of the size of the Earth, though I do not know this for a fact offhand and the person who originally posted this claim needs to come up with a citation. An authoritative source here doesn't say anything about Eratosthenes having proven that the Earth was spherical.
- I agree totally and wholeheartily apologise. I snapped and it was totally without merit. My bad. I don't want it to sound like an attempt at justification, but I did remove it because of the lack of citation, although not stating it. I thought about it in the context of his method of measurement of Earth's circumpherence, where the local sphericity would correspond to his local (Alexandria and to the south) measurements, but stretching this over to the whole Earth seemed like a stretch (although guided by the Occam's razor). Shades of Earth on the Moon is something that just didn't jump into my head though it seems obvious, now. Interesting, the capacity of the mind to treat something as natural and without need for an explanation, just because it is always there.
- Another thing is the OR charge, which is all too frequently wielded on Wikipedia to my taste. For instance, I don't need any sources to support your "claim" that Earth shadows on the Moon prove its sphericity. Although were I to believe the Moon and its phases to be just some gods' play thing, a magical show, some picture up in the skies (especially as it seems to be not rotating), that would still prove nothing to me. Then I could only have my proof by actually seeing the Earth and the Moon as seen from some orbiting rocket. So we still need a prove that Eratosthenes didn't hold these beliefs, that he actually made notice of Earth's shadow on the Moon's face and interpreted it in that way. We can't just assume that. WillNess (talk) 12:25, 19 June 2011 (UTC)
- I have put into my calendar a note to resolve the issue on July 2, unless someone posts a citation and/or I receive appropriate information from my correspondents that the current information is correct.
- According to Spherical Earth, Aristotle, in the century before Eratosthenes, gave three proofs of the shape of the Earth, including the one I mentioned about the uniformly circular shape of the shadow of the Earth during an eclipse. Citations to Aristotle's work are given.
(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)
A drawing would help
I think, a drawing would help to understand the method of Eratosthenes. Who can make and insert it? --22.214.171.124 01:23, 1 May 2007 (UTC)
"He also made what he thought was a map of the Earth."
The above text appears in the first paragraph - it implies that Eratosthenes was somehow wrong, and that he hadn't actually created a map of the Earth. I think it needs better wording - just because it wasn't particularly accurate, doesn't make it any less a map of the Earth. David 10:34, 23 May 2007 (UTC)
The report should at least be mentioned of a fleet equipped by Eratosthenes in 232 BC to circumnavigate the Earth heading East through the Indian Ocean and reaching the Isthmus of Panama. The crew was Cyrenaican (Libyan), captain Rata and navigator Maui. Inscriptions around the Pacific and Maori Legends tell of events. The controversial name of Barry Fell, who grew up with Maori children, is attached to this. This reference is in Italian: http://www.liutprand.it/Eratost.htm hgwb 19:17, 9 June 2007 (UTC)
One question about measurement of the Earth
One thing I've wondered is, how was Eratosthenes able to determine the exact time to make the measurement places 800 km from each other? I can think of a few ways it could be done, but all would have a high degree of error given what would be available at the time, I'm wondering if there is any evidence showing how he did it himself. -- Suso 03:28, 12 June 2007 (UTC)
If you measure at noon, the shadow of a vertical stick is going to be shortest. So, just trace the tip of the shadow in sand or on a paper. An added advantage is that you don't have to line up one spot exactly north of the other - the error is not that important if you know exactly how far apart they are going straight up north. (measuring the funny shadow line can be done later, in the afternoon or the next day. retostamm 13:57, 20 Aug 2007 (PST).
- The original claim that Eratosthenes had heard (he did not make this observation himself) was that there was a well in Syene (near modern Aswan) where one could see the Sun reflected from the bottom of the well at (local) noon on the date of the summer solstice. That means that the Sun was directly overhead at noon on that date. The same measurement at Alexandria, where Eratosthenes lived, on the same date gives an altitude that is not 90 degrees (if memory serves, it is 7.5 degrees short, which means that the latitude of Alexandria is 31 degrees, which is about right.) I believe that this is documented with sources in Arthur Koestler's The Sleepwalkers.
- So, there is no ambiguity in the data Eratosthenes was relying on. Bill Jefferys (talk) 23:18, 18 June 2011 (UTC)
In the text, in an article by Rawlins, "5000" appears twice. In the original, it appears once. —Preceding unsigned comment added by 126.96.36.199 (talk) 13:09, 22 December 2007 (UTC) This depends on the computer used.
I have now added the Sieve in a brief section called Prime Numbers. This is in addition to the mention in Named after Eratosthenes, which was not really satisfactory since the Sieve is something he actually discovered himself, as opposed to the other entries which were just named in his honour long after his death. Dirac66 (talk) 02:56, 15 March 2009 (UTC)
In Book II of the History Herodotus gives an accurate measure of the Earths equatorial circumference which he attributes to the Egyptians. Since Herodotus lived before Eratosthenes how was it that the Egyptians arrived at their figures? Furlong refers to the Greek stadion of 185m. So Herodotus is making the proportion of the schoene of the Egyptians = 1/10 degree of the Earths equatorial circumference as accurately as can be determined.
The length of the country along shore, according to the bounds that we assign to Egypt, namely from the Plinthinetic gulf to Lake Serbonis, which extends along the base of Mount Casius, is sixty schoenes. The nations whose territories are scanty measure them by the fathom; those whose bounds are less confined, by the furlong; those who have an ample territory, by the parasang; but if men have a country which is very vast, they measure it by the schoene. Now the length of the parasang is thirty furlongs, but the schoene, which is an Egyptian measure, is sixty furlongs. Thus the coastline of Egypt would extend a length of three thousand six hundred furlongs.
Just want to double-check that we're all on the same page here and that it's the correct page.
Article previously had his dates shown as 276 BC - 194 BC.
I see a number of online sources with the "276 BC" date, and many of these appear not to be clones of this article.
What's the correct date and cite for same, or what are the sources for various guesses for the date?
- You are quite right. User:W.A._Ribeiro_Jr. should have given a source for his change. I don't know the ancient source for the date, but most pages on the internet seem to agree on 276 BC, including the article on Eratosthenes maintained by The MacTutor History of Mathematics of the School of Mathematics and Statistics, University of St Andrews, Scotland, which seems reliable enough. I will therefore change the year back to 276. --Fabullus (talk) 07:59, 7 February 2009 (UTC)
- I looked this up. The ancient source for the date seems to be the Suda, which gives 276-272 BC (Olympiad 126) for his year of birth. The question of whether he was born earlier seems to hinge on a comment by Strabo that Eratosthenes was a "γνωριμος" of Zeno of Citium (who died c. 262 BC). "γνωριμος" often means "pupil", which would imply that Eratosthenes must have been born a bit earlier to have been old enough to study Stoic philosophy under him, but, on the other hand, "γνωριμος" can also mean "acquaintance." The Dictionary of Scientific Biography, where I got most of this from, even states that one scholar puts the year-of-birth as early as 296 on the basis that there was copyist error in the Suda and he was actually born in the 121st Olympiad. Singinglemon (talk) 20:16, 12 February 2009 (UTC)
Eratosthenes and the Alexandria lighthouse ...
Its not too hard to explain why this section is so hard to read: If you go back to a version of Jan 2009 all is well. But then somebody must have deleted the preceeding paragraph ... Regards --Boobarkee (talk) 13:14, 17 August 2009 (UTC)
- There was a section deleted by a vandal at 15:56, 11 March 2009 and then there was another vandalism which was not reverted far enough. See history --Alastair Rae (talk) 14:46, 7 October 2009 (UTC)
"By 194 B.C, Eratosthenes became blind. He died in 195 B.C, at the age of 80-82."
Your remark is valid, although you swapped the numbers above. Of course being dead implies being blind, but that's not an accepted way to relate to facts in a serious encyclopedic something. Rursus dixit. (mbork3!) 20:21, 10 October 2010 (UTC)
Pronunciation of the name (stress placement)
The article says:
Following in the footsteps of Eratosthenes (La Main à la Pâte)
- Project: lamap.inrp.fr/eratos/
Since sept 2000, thousands pupils in intermediate course have measured the Earth's circumference from their classroom, simply by observing the shadow of a vertical stick at noon local solar time. Schools of many countries join together to reproduce the observations of the Greek scientist who, more than 2000 years ago, was the first to propose a simple method to measure our planet's size.
The Noonday Project (Center for Innovation in Engineering and Science Education (CIESE))
- Project : ciese.org/curriculum/noonday/
The Goal of the Noon Day Project is to have students measure the circumference of the earth using a method that was first used by Eratosthenes over 2000 years ago. Students at various sites around the world will measure shadows cast by a meter stick and compare their results. From this data students will be able to calculate the circumference of the earth. —Preceding unsigned comment added by Perbosc (talk • contribs) 23:03, 11 July 2010 (UTC)
Point of the portrait?
I have never understood the need to post "portraits" of ancient people whose true likenesses are completely and utterly unknown to us. Why are they there? Can we remove them? In my opinion, they add absolutely nothing to the article. They would be useful in an article about the life of the artist, but that is all. Frankly, the guy in the picture doesn't even look particularly Greek!188.8.131.52 (talk) 22:40, 26 July 2010 (UTC)
The citation request is for the given sources of inaccuracy. The paragraphs commenting on the inaccuracies in E's estimates for the circumference of the earth are not sourced. I of course agree with the other editor's comment about not needing a source to say that the sun is not a point source. It's the main paragraph before (and after for that matter) that is not sourced. Who stated for instance that one error comes from the location of Syene? Who stated that it was difficult to measure distances accurately. I do not doubt that the statements are correct, but an inline citation would be nice. --AnnekeBart (talk) 16:37, 31 March 2011 (UTC)
Will be trying to help improve this article as a paper for my History of Science class. I want to use these sources as premises to expound on Eratosthene's Bibliography.
- Lukoševičius, Viktoras, and Tomas Duksa. "Eratosthenes' Map of the Oecumene." Geodesy & Cartography 38.2
- Lindberg, David C. The Beginnings of Western Science: The European Scientific Tradition in Philosophical,
Religious, and Institutional Context, Prehistory to A.D. 1450. 2nd ed. Chicago: University of Chicago, 2007.
- Zeigler, Donald J. "From Prime Numbers to Place Names: A New Use for Eratosthenes' Sieve." California Geographer
- Bailey, Ellen. "Eratosthenes of Cyrene." Eratosthenes of Cyrene (2006): 1-3.
- Spruch, Grace Marmor. "The Legend Of Christopher Columbus." American Scholar 71.4 (2002): 61. Literary
- Gow, Mary. Measuring the Earth: Eratosthenes and His Celestial Geometry
Ancient perspectives : maps and their place in Mesopotamia, Egypt, Greece, and Rome
- Talbert, Richard J. A. Ancient Perspectives: Maps and Their Place in Mesopotamia, Egypt, Greece, and Rome.
- Eratosthenes. Eratosthenes' Geography/fragments collected and translated, with commentary and additional
material, by Duane W. Roller
- Nicastro, Nicholas. Circumference: Eratosthenes and the Ancient Quest to Measure the Globe.
Capital of Ptolemaic Egypt?
- There is no reason to suppose that Eratosthenes ever had the slightest dealings with a light-house. — Preceding unsigned comment added by 184.108.40.206 (talk) 17:44, 23 November 2011 (UTC)
- Posidonius used a similar method with accurate results, without using any light-house. — Preceding unsigned comment added by 220.127.116.11 (talk) 14:29, 25 November 2011 (UTC)
Earth measurement information
Should something be done about the fact that the measurement of the circumference of the Earth seems to contradict the information on the History of geodesy page? Simoneister (talk) 09:48, 21 February 2012 (UTC)
- I will be accused of trolling if I give the reason for this. — Preceding unsigned comment added by 18.104.22.168 (talk) 13:17, 28 February 2012 (UTC)
Concerning this from the article:
"Eratosthenes criticized Aristotle for arguing that humanity was divided into Greeks and barbarians, and that the Greeks should keep themselves racially pure, believing there was good and bad in every nation."
The W.W. Tarn book is not available on line, but I found it at a book store. I did not pay out the $100 for the two-volume set. However, on page 439 of volume two the discussion is about a fragment attributed to Eratosthenes in which he relates an interchange between Aristotle and Alexander the Great. Aristotle reportedly counseled Alexander to treat Greeks one way, foreigners another. Alexander reportedly disagreed and felt that all humanity should more or less get along and marry whomever. It's interesting, but it is Eratosthenes' account of an interchange between two different people. Racial "purity" is not part of the discussion. Please note, the fragment is basically hearsay. — Preceding unsigned comment added by 22.214.171.124 (talk) 11:56, 6 April 2012 (UTC)
Shouldn't computer scientist be part of the opening description as well? I tried adding it but it got reverted.
Computer scientist should be added given his contributions of several algorithms, most notably the Sieve of Eratosthenes. — Preceding unsigned comment added by 126.96.36.199 (talk) 22:02, 8 December 2012 (UTC)
- Because of the algorithms he designed, he is usally called a mathematician! --Boobarkee (talk) 10:39, 1 October 2013 (UTC)
I thought it might be a great idea to add the formula that Eratosthenes used to calculate the circumference of the Earth. He used the rod to find that in Alexandria it casted a shadow 7.5 degrees, this same day it would cast no shadow in Syene, due south of Alexandria. He then formulated that Earth's circumference divided by distance in stades from Syene to Alexandria (5250) would equal 360 degrees (Earths diameter) divided by the shadow casted in Alexandria, 7.5 degrees. Cross multiply these values 360 and 5250 and divide by 7.5 to get 252,000 stades. Which is so very close to Earth's real circumference.  ToothFairyJenny (talk) 03:09, 20 September 2013 (UTC)
History of Science Edits
I really find this article fascinating. I do have some suggestions to clean up the biography. The opening introduction talks about all of his work. Maybe add more on who he was as person versus just explaining his work in the opening introduction.
Life: In this paragraph I found it sometimes hard to follow the sequence of events. It has very good information here, but maybe just a little clean up with the timeline of his life.
Measurement of the Earth's Circumference: I particularly enjoyed this section. I am very nerdy for statistics and numbers, this paragraph fulfilled my needs. The picture showing part of the globe from space was a very good add. The only suggestion for this section is to add some sources of where you found these statistics of Eratosthenes calculations. Without proper sources I just assume these numbers are made up.
Geography: Very good flow of sources listed in this section. I would suggest moving the History of Geodesy from the top of the ==geography== section to your ==external links== section. This provides a neat and clean order/flow to the page for the reader to follow. I found this section difficult to read, due to some grammatical errors. For instances, "In the Library of Alexandria he had access to scattered books of travel inside them countless information and representations that needed to be pieced together in some organized format," does not flow well. Maybe put a comma or a period between the words "travel" and "inside." Clean up minor grammatical errors like this and this section will be stellar.
Other Astronomical Distances: Looks like the Wikipedia Gods have already punished this article haha. I don't have much to say other then repeat what the Wiki Gods have already suggested. This section could be deleted, and use space the information out in this section amongst the entire article. This would clean up the article, and also not make it as beefy. Also, a picture would be nice here to spice up the section.
Prime Numbers: I like the moving digital picture explaining prime numbers. I see the article explains prime numbers, but where did Eratosthenes generate this algorithm? Why did he come up with this algorithm? Expand more on this paragraph, and add sources to where you found this information.
Switch the ==Works== Section and the ==Things named after Eratosthenes==. Maybe put the things named after Eratosthenes as a subsection of further readings or external links. This would clean the page up a bit more.
Final Notes: Jenny I really liked your article on Eratosthenes. He sounds like a very fascinating individual, with many contributions to the fields of mathematics and science. The article has plenty of information. The only suggestions are minor and should be taken with a grain of salt. Other then cleaning up the layout of the article, adding some sources, fixing minor grammatical changes, and elaborating more on some sections and cutting out some of the beef in other sections, this page was very well written. I disagree with the Wikipedia Gods rating this page as a C-class importance page. This man sounds like his discoveries were pivotal for the creation on geography, advance mathematics, and advanced science. This page should be Class-A with very high importance. Mavorik1 (talk) 17:56, 18 November 2013 (UTC)
Eratosthenes was a berber, there is berber tribes in Eypte and Libya and he have not been came with greeks, he was born in Libya, so he is not greek, he is berber. Why all people stole from us our scientists. — Preceding unsigned comment added by Berber027 (talk • contribs) 15:58, 31 March 2014 (UTC)
- The Beginnings of Western Science, David Lindberg