Ancient Geography by Duane W. Roller

Author:Duane W. Roller
Language: eng
Format: epub
ISBN: 9780857739230
Publisher: I.B.Tauris

Hipparchos of Nikaia

The most serious early critic of Eratosthenes was Hipparchos, active in the second century BC; the latest date associated with him is 126 BC.41 He was from Nikaia in northwestern Anatolia but spent most of his academic career on Rhodes. Hipparchos was not a geographer, but a mathematician and astronomer. He wrote a single work of relevance to the history of geography: Against the “Geography” of Eratosthenes, which nonetheless is more mathematical than geographical. It survives in 63 fragments, 55 of which are from Strabo's Geography, and thus there is the same difficulty in assessing Hipparchos’ contribution as there is with Eratosthenes: in fact the two are often tangled together in Strabo's recension, coupled with Strabo's own comments.

Hipparchos’ treatise was in three books, the same as the work that he sought to refute.42 His complaint was that Eratosthenes based his distances and positioning of toponyms on hearsay reports, and he believed, quite reasonably, that the only accurate way to locate places was through mathematics and astronomy, not travelers’ accounts.43 He had mathematical skills that Eratosthenes did not, most notably an ability at what would today be called trigonometry, and developed an astronomical method of positioning places on the surface of the earth.44 The flaw in his reasoning is not his methodology, but that implementation of such a technique would require a competent observer on the ground at each point, something obviously impossible, at least at that time. Thus Hipparchos was beholden to Eratosthenes’ system of information received—especially for remote places—while realizing, as had Eratosthenes, its flaws.

Nevertheless Hipparchos made a number of alterations to Eratosthenes’ scheme of the oikoumene, most of which were improvements, although some actually made Eratosthenes’ data worse. Hipparchos was able to adjust the main parallel somewhat, moving it to the south in the western Mediterranean,45 and he made other corrections in this region (with the fall of Carthage in 146 BC, the west had become better known to Greeks). He realized that something was wrong with the positioning of India and the Imaos Mountains, but eliminated Eratosthenes’ partial correction and reverted to the older, more erroneous data.46 This may have had a cascading effect elsewhere, since he validated the assumption that Byzantion and Massalia were on the same latitude, when their parallels are actually 2o apart. But he did provide as many astronomically determined locations as possible (although these were few) and outlined the techniques for doing so.47

Hipparchos’ contribution to geography is not so much his critique of Eratosthenes’ methodology as his understanding that an accurate conception of the oikoumene was only possible through precise positioning of toponyms and features, and that this depended on astronomy, not travelers’ information. It was impossible to apply this theory consistently—something that Hipparchos himself understood—but nonetheless he created the basic theory of mapping.48 Yet like all such endeavors before the eighteenth century, Hipparchos was hampered by the difficulties in determining longitude, although he realized that observation of eclipses at separate points on the same parallel would provide the information.

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