Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

ERATOSTHENES OF ALEXANDRIA (c. 276-C....

Online Encyclopedia
Originally appearing in Volume V09, Page 733 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

ERATOSTHENES OF See also:

ALEXANDRIA (c. 276-C. 194 B.C.) , See also:Greek scientific writer, was See also:born at See also:Cyrene. He studied See also:grammar under See also:Callimachus at Alexandria, and See also:philosophy under the Stoic Ariston and the See also:Academic See also:Arcesilaus at See also:Athens. He re-turned to Alexandria at the See also:summons of See also:Ptolemy III. Euergetes, by whom he was appointed See also:chief librarian in See also:place of Callimachus. He is said to have died of voluntary See also:starvation, being threatened with See also:total See also:blindness. Eratosthenes was one of the most learned men of antiquity, and wrote on a See also:great number of subjects. He was the first to See also:call himself Philologos (in the sense of the " friend of learning "), and the name Pentathlos was bestowed upon him in See also:honour of his varied accomplishments. He was also called Beta as being second in all branches of learning, though not actually first in any. In See also:mathematics he wrote two books On means (IIEpi u aorirwv) which are lost, but appear, from a remark of Pappus, to have dealt with " loci with reference to means." He devised a See also:mechanical construction for two mean proportionals, reproduced by Pappus and Eutocius (See also:Comm. on See also:Archimedes). His K6CO acoV or See also:sieve (cribrum Eratosthenis) was a See also:device for discovering all See also:prime See also:numbers.

He laid the See also:

foundation of mathematical See also:geography in his Geographica, in three books. His greatest achievement was his measurement of the See also:earth. Being informed that at Syene (See also:Assuan), on the See also:day of the summer See also:solstice at See also:noon, a well was lit up through all its See also:depth, so that Syene See also:lay on the tropic, he measured, at the same See also:hour,the See also:zenith distance of the See also:sun at Alexandria. He thus found the distance between Syene and Alexandria (known to be 5000 stadia) to correspond to -nth of a great circle, and so arrivedat 250,000 stadia (which he seems subsequently to have corrected to 252,000) as the circumference of the earth. He is credited by Ptolemy and his commentator See also:Theon with having found the distance between the tropics to be a rds. of the See also:meridian circle, which gives 23° 51' 20" for the obliquity of the See also:ecliptic. His astronomical poem See also:Hermes began apparently with the See also:birth and exploits of Hermes, then passed to the See also:legend of his having ordered the heavens, the zones and the stars, and gave a See also:history of the latter. His See also:Erigone, of which a few fragments are also preserved, is sometimes spoken of as a See also:separate poem, but it may have belonged to the Hermes, which appears also to have been known by other names such as Catalogi. The still extant Catasterismi, containing the See also:story of certain stars in See also:prose, is probably not by Eratosthenes. Eratosthenes was the founder of scientific See also:chronology in his xpovoypacbia in which he endeavoured to See also:fix the See also:dates of the chief See also:literary and See also:political events from the See also:conquest of See also:Troy. An important See also:work was his See also:treatise on the old See also:comedy, dealing with theatres and theatrical apparatus generally, and discussing the See also:works of the See also:principal comic poets themselves. Works on moral philosophy, history, and a number of letters were also attributed to him. There is a See also:complete edition of the fragments of Eratosthenes by See also:Bernhardy (1822); poetical fragments, Hillier (1872); See also:geographical, Seidel (1799) and Berger (188o) ; Karao-rspuQ¢ol, Schaubach (1795) and See also:Robert (1878).

See See also:

Sandys, Hist. Class. Schol. i. (1906). (T. L.

End of Article: ERATOSTHENES OF ALEXANDRIA (c. 276-C. 194 B.C.)

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
ERASTUS, THOMAS (1524-1583) 		[next]
ERATURE

Site © 2006 - Net Industries