What Columbus Didn’t Know
Peter Green
- The Extraordinary Voyage of Pytheas the Greek, the Man who Discovered Britain by Barry Cunliffe
Allen Lane, 182 pp, £12.99, October 2001, ISBN 0 7139 9509 2
- Ptolemy’s Geography: An Annotated Translation of the Theoretical Chapters edited by J. Lennart Berggren and Alexander Jones
Princeton, 232 pp, £17.95, January 2002, ISBN 0 691 09259 1
- Barrington Atlas of the Greek and Roman World: Atlas and Map-By-Map Directory by Richard J.A. Talbert
Princeton, three volumes, £300.00, September 2000, ISBN 0 691 03169 X
These three books constitute both landmarks and cautionary warnings in a long process that none of them addresses directly. Take Barry Cunliffe’s reconstruction of the exploratory voyage by Pytheas of Massalia (Marseille) in the late fourth century BC: this not only exposes the striking lack of direct knowledge then prevalent among Mediterranean peoples about virtually anywhere outside their own charmed climatic circle, but suggests the powerful emotional liminality that is always around to reinforce ignorance. Pytheas’ sober and specific report on Cornish tin mines, the amber trade and (probably) Iceland and the Arctic Circle got him branded as a liar by writers such as the geographer Strabo, who preferred the authority of myth, and was equally ready to dismiss Megasthenes’ first-hand descriptions of India on the same basis. Ptolemy of Alexandria (c.90-168 AD), the theoretical chapters of whose Geography we now have in a superlative new translation, was the first systematic cartographer to introduce the mapping of geographical points by precise co-ordination of parallel and meridian; but he also rejected both Eratosthenes’ near-accurate calculation of the Earth’s circumference and, worse, Aristarchus’ theory of a heliocentric universe in favour of the old (and psychologically more satisfying) geocentric worldview supported by Aristotle. Since his own achievement ensured his subsequent enshrinement as an unquestioned authority, these two cardinal errors were guaranteed an extraordinarily long shelf-life. Finally, the Barrington Atlas of the Greek and Roman World, which triumphantly incorporates all the latest developments of computerised geographic information systems (GIS), still has to struggle with human error and prejudice when reluctantly confronted with political rather than physical data, and (perhaps because of this) takes its lead, fashionably, from Fernand Braudel in privileging the latter whenever possible.
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Letters
Vol. 24 No. 6 · 21 March 2002
From Piotr Jozefow
Peter Green's discussion of ancient maps (LRB, 21 February) reminded me of an anarcho-tourist grouping from the late 1960s with which I was briefly involved. The idea behind Scramble! (the title was suggested by its Scottish founding member, the concrete poet and printmaker Greg Ross) was that tourism was a function of capitalist control whose systems had to be subverted. Not only that, but the corporate city with its directions and signposts was an expression of chartered space which had to be broken down. Not content with pointing visitors to London in wrong directions, Scramble! produced deliberately confusing maps. These might be made of bread or of toothpicks inserted into assemblages of steel wool and masticated paper. The most effective at outright confusion were simply maps of cities different from those we happened to be in at the time. Thus a visit to Paris would require a plan of Istanbul. With these tactics we attempted to deprogramme ourselves of the urban knowledge that any city-dweller or casual visitor would deem essential. We failed, needless to say, but had a lot of fun baffling ourselves as well as tourists.
Piotr Jozefow
London W11
From Paul Pritchard
Peter Green finds fault with Ptolemy for rejecting 'both Eratosthenes' near-accurate calculation of the Earth's circumference and, worse, Aristarchus' theory of a heliocentric universe in favour of the old … geocentric worldview supported by Aristotle.' But Eratosthenes wasn't trying to measure the circumference of the Earth, any more than Aristarchus, in On the Sizes and Distances of the Sun and the Moon, was trying to measure the sizes and distances of the Sun and the Moon. Eratosthenes and Aristarchus were Platonists, following the strictures of the Republic that the beautiful but imperfect heavens should be left alone, and the mind turned to pursuing hypotheses: in general, that the world is modelled on a rational paradigm; in particular, that this involves circles and spheres. Astronomy in this mould becomes a branch of pure mathematics, the study of spheres in motion. If you want to exhibit a general method (e.g. to find the circumference of the Earth given two points on the same meridian a given distance apart etc), in the absence of symbolic algebra, in particular lacking the notion of the (algebraic) formula, the only technique available is to work it through with dummy values, and get a dummy result – which proves that you could get the true result by inserting true values. Ptolemy would have had to have been a dummy himself to take Eratosthenes' dummy (if fortuitously accurate) result seriously.
Paul Pritchard
Crumlin, Gwent
Vol. 24 No. 7 · 4 April 2002
From Steve Baiocchi
While befuddled tourists and easily humoured out-of-towners may have cheerful memories of Scramble!'s sophomoric pranksterism, there is an aspect of their activities which Piotr Jozefow doesn't mention (Letters, 21 March). No one who was present at those Powys Square meetings in the late 1960s and early 1970s could have had any illusions as to the aims of Gregor Ross's inner circle. Many of these people had connections with direct action groups, and if I'm not mistaken there was a sizeable input from associates of the Angry Brigade. (Since Jozefow still lives in that neck of the woods, maybe he should take a stroll round and remind himself of what went on in the basement of No. 8. Or maybe that's all been gentrified, too.) Those art-school assemblage maps were fluff. Ross's idea of reimagining the city was to level it. He spent a year in Naples, where people knew how to wire large structures with explosives (under the cover of New Year fireworks, Camorristi owners sometimes blow up unwanted buildings). Admiration for Provos changing Derry street-names to Gaelic was another of Ross's weekend fads, and there must be some of Jozefow's neighbours who recall his Erse-ing of the Signs in 1972. His manifestos advocated attacks on property and the abandoning of what he called the 'noxious bourgeois fraud called civics', which really meant: let all hell break loose and see what is left once the dust has settled. Ross belonged to that class of spoilt suburbanite prigs who have an almost Puritan hatred for the city. 'The ideal city is the desert' was one of Scramble!'s dumber slogans. Ross's Maoist back-to-nature fantasies were hitched to theories filched from the 1960s architectural avant-garde. You can see the results of that particular experiment, even in Bloomsbury. The real test of Scramble! wasn't pointing tourists getting off the No. 12 bus in the direction of the Blue Mosque, but the Clun commune in 1973. And a grim experience that was. Any environment advertising itself as canvas Corbusier has to be structurally unsound at best. Ross had an undoubted flair for self-publicity and was a talented intaglio printmaker, but he revealed a hysterical incompetence when it came to organising anything without a laundry or convenience store in sight. Just because Scramble! is remembered for hippyish japes like edible A-Zs shouldn't blind anyone to the fact that here was a group thought by some to have had intimate links with self-proclaimed terrorists. Sure, Ross and his cohorts were unlikely to blow up the Westway all by themselves, but they were prepared for violence morally and ideologically.
Steve Baiocchi
New York
Vol. 24 No. 8 · 25 April 2002
From Peter Green
Paul Pritchard (Letters, 21 March) turns Eratosthenes and Aristarchos into wholehogging Platonists determined, as was the Master, to abhor vulgar specifics. Like so many Platonic generalisations, this one won't wash. Of course the ideal of sphericity (as I made clear in my review) affected research. Certainly Eratosthenes was influenced by Platonism (as his poem Hermes and his training under Arcesilas make clear). But he was also a practical mathematician in pursuit of real, not dummy, answers – inter alia for the length of the Mediterranean. As for Aristarchos, he was, if anything, a Peripatetic, having been trained by Strato of Lampsakos. And Ptolemy still backed the wrong horse.
Peter Green
Iowa City
From Paul Pfalzner
There is no way that Paul Pritchard can get around the fact that Eratosthenes did indeed identify a valid method to determine the circumference of the Earth based on simple measurements of angles and distances on Earth and, what is more, carried out the procedure with a remarkable degree of accuracy. Pritchard makes much of the prevailing Platonism ('circles and spheres'; 'heavens should be left alone') and the absence of algebraic symbols. He does not seem to realise that the method of Eratosthenes involves simple ratios, not the use of 'dummy' values in an algebraic equation. And in no way does it follow, as Pritchard maintains in his defence of Ptolemy the astronomer, that 'Ptolemy would have had to be a dummy himself to take Eratosthenes' dummy results seriously.' Whether Eratosthenes was 'trying to measure' or not hardly seems relevant. The fact is that he did – regardless of Platonist ideas, regardless of not being in possession of symbolic algebra – and that his method is valid, and can give accurate results when based on accurate measurements. It seems strange that someone would go out of his way, based on nothing more than claims about Platonism, to question a great man's unique achievements.
Paul Pfalzner
Ottawa
Vol. 24 No. 9 · 9 May 2002
From Paul Pritchard
I would not wish to 'get around the fact that Eratosthenes did indeed identify a valid method to determine the circumference of the earth', as Paul Pfalzner suggests (Letters, 25 April), but I don't see why anyone should believe that he 'carried out the procedure with a remarkable degree of accuracy'. Eratosthenes' calculation relies on the following data: that the distance from Syene to Alexandria is 5000 stadia; that Alexandria is due north of Syene; that the difference in latitude between Alexandria and Syene is 1/50th part of a great circle. Given these data a simple calculation gives the circumference of the Earth as 250,000 stadia. If we accept Pliny's value for the stadion used by Eratosthenes, and Heron's mysteriously exaggerated figure of 252,000 stadia, this gives a polar diameter only 50 miles short of the true polar diameter.
Unfortunately, Heron's figure is wrong, Pliny's opinion of doubtful worth, Alexandria is not due north of Syene, nor is 1/50th part of a great circle an accurate figure for their difference in latitude. Who is willing to believe that Alexandria is exactly 5000 stadia from Syene, whatever the value of the stadion? Where do we think Eratosthenes got this figure in the first place? What kind of 'procedure' was involved? Did he triangulate his way from Syene to Alexandria loaded with calibrated chains and surveying equipment? I don't think so. As for Peter Green's parting shot, backing the wrong horse is no disgrace, providing you had good reason to put your money on it.
Paul Pritchard
Crumlin, Gwent
