Cerebral de eratosthenes biography
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Life
Eratosthenes was born around 276 B.C.E. in Cyrene (in modern-day Libya), but lived and worked in Alexandria, capital of Ptolemaic Egypt.
Although Eratosthenes' method was well founded, the accuracy of his calculation was inherently limited. Still another piece, Catasterismi, has survived to the present day.
The letter describes the history of the problem of the duplication of the cube and, in particular, it describes a mechanical device invented by Eratosthenes to find line segments x and y so that, for given segments a and b,
a:x=x:y=y:b.
By the famous result of Hippocrates it was known that solving the problem of finding two mean proportionals between a number and its double was equivalent to solving the problem of duplicating the cube.London, Oxford University Press, 1971. Exact Sci.37(4)(1987), 359-363.
One of the important works of Eratosthenes was Platonicus which dealt with the mathematics which underlie Plato's philosophy.
The library was based on copies of the works in the library of Aristotle. He also suggested that lakes were the source of the river.
Works
- On the Measurement of the Earth (lost, summarized by Cleomedes)
- Geographica (lost, criticized by Strabo)
- Arsinoe (a memoir of queen Arsinoe III of Egypt; lost; quoted by Athenaeus in the Deipnosophistae)
- A fragmentary collection of Hellenistic myths about the constellations, called Catasterismi(Katasterismoi), was attributed to Eratosthenes, perhaps to add to its credibility.
Named after Eratosthenes
- Sieve of Eratosthenes
- Eratosthenes crater on the Moon
- Eratosthenian period in the lunar geologic timescale
- Eratosthenes Seamount in the eastern Mediterranean Sea
References
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- Boyer, Carl B., and Uta C.
Merzbach. Only Hipparchus, Strabo, and Ptolemy were able to make more accurate maps in the classical and post-classical world.
- A number of works on theater and ethics
- A calendar with leap years, in which he attempted to work out the precise dates and relations of various events in politics and literature from his day back to the Trojan War.
The mysterious astronomical distances
Eusebius of Caesarea in his Preparation for the Gospel|Praeparatio Evangelica includes a brief chapter of three sentences on celestial distances (Book XV, Chapter 53).
Ptolemy's reference to Eratosthenes in Almagest I.12, Centaurus 27(2)(1984), 165-167.
Additional Resources (show)
Written by J J O'Connor and E F Robertson
Last Update January 1999
| Eratosthenes | |
|---|---|
| Mathematician | |
| Born | 276 BC Cyrene |
| Died | 194 BC Alexandria |
| Nationality | Greek |
Eratosthenes was a mathematician from ancient Greece.
He also constructed a simple machine, which was later reproduced by Eutocius and Pappus, for demonstrating the theory of two mean proportionals. The distance Eusebius quotes for the moon is much too low (about 144,000 km); Eratosthenes should have been able to be more accurate than this since he knew the size of the earth and Aristarchos of Samos had already found the ratio of the moon's distance to the size of the earth.
All multiples of three are crossed off, and so on. An original Arabic text of this letter was once kept in the library of the St Joseph University in Beirut. From remarks made by some of his contemporaries, it seems that they touched on the nature of means and loci.
Discoveries and Measurements
Eratosthenes is best known today for his “Sieve,” a method for isolating prime numbers.
But if what Eusebius wrote was pure fiction, then it is difficult to explain the fact that, using the Greek stadium of 185 meters, the figure of 804 million stadia that he quotes for the distance to the sun comes to 149 million kilometers. Hist. It is certainly true that Eratosthenes obtained a good result, even a remarkable result if one takes 157.2 metres for the stadium as some have deduced from values given by Pliny.
The idea for the calculation came to him after he was told that a certain well in Syene was illuminated to its bottom on the summer solstice, whereas this phenomenon did not occur at Alexandria. The meaning depends on whether Eusebius meant 400 myriad plus 80000 or "400 and 80000" myriad.
Another book written by Eratosthenes was On means and, although it is now lost, it is mentioned by Pappus as one of the great books of geometry.
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