Le jeudi 8 novembre 2012 à 14h, en salle de conf de l'OSUR (campus de Beaulieu, bâtiment 14B, RDC), Lucio Russo donne une conférence intitulée
Le jeudi 8 novembre 2012 à 14h
, en salle de conf de l'OSUR (campus de Beaulieu, bâtiment 14B, RDC), Lucio Russo donne une conférence intituléeAchievements and practices of the Hellenistic Science: Ptolemy’s longitudes and Eratosthenes' Measurement of the Earth's Circumference
Lucio Russo est Professeur de Mathématiques à l'Université de RomePrésentation :
1. The problem. Since antiquity Eratosthenes’ measurement of the Earth’s circumference is one of the most celebrated achievements of Hellenistic science, but the accuracy of his result (252,000 “stadia”) can’t be evaluated without knowing the actual length of his “stadion”. According the value determined by Hultsch in 1882, Eratosthenes’ error should have been less than 1%. Such accuracy was impossible to achieve without a topographical survey of all Egypt and the preparation of accurate maps. In the second half of the XX century, however, another evaluation of the stadion has prevailed, implying an error of about 17%. On the basis of this new estimate, many have argued that Eratosthenes had made a crude valuation and not a true measurement and the opinion has prevailed that at Eratosthenes’ time there was no quantitative cartography.
The true value of the stadion used by Eratosthenes has thus become an important issue to assess the effectiveness of hellenistic science and the resources available to scientists at that time.
2. The new results. A statistical analysis of the longitudes reported in Ptolemy’s Geographia shows that many of them were obtained by distorting in a linear way data which were known with a remarkable accuracy. As a consequence, it has been possible to obtain an estimate of the value of the stadion which essentially confirms the value which Hultsch had determined in 1882 on philological bases.
Possible reconstructions of some features of Eratosthenes’ measurement, which had been altered by Cleomedes in his extant report, are also discussed.
Contact : Lucio Russo (Université de Rome)Contact OSUR : Rita Compatangelo-Soussignan