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    Gavin Menzies and "1421"
    From: George Huxtable
    Date: 2005 Dec 26, 11:42 -0000

    A couple of years ago, or so, Gavin Menzies' book "1421; the year China discovered the world" was
    discussed in Nav-L. The question centred on whether the suggested method for determining longitudes
    from on-land was plausible. We agreed that it probably was.
    
    Since then, I've read the book (paperback, 2003), and come to the firm conclusion that the whole
    thing is an extraordinary goulasch of nonsense. Let me explain why, to see if anyone who has read it
    agrees with that view. Those that haven't will find that the rest of this mailing makes little
    sense.
    
    ================
    
    What shook me was to read the following on page 35-
    
    "... It seemed arrogance bordering on hubris to beleive that a retired suibmarine captain could
    reveal a story many great minds had failed to unearth, but ... I started off with one crucial
    advantage. In 1953, when I joined the Royal Navy at the age of fifteen ... During my seventeen
    years in the Navy I sailed the world in the wake of the great European explorers. Between 1968 and
    1970, for example, I was in command of HMS Rorqual and took her from China to Australasia, the
    Pacific and the Americas.
    
    ...... In those days satellite navigation was unlnown; we had to find our way by the stars. I saw
    the same stars those great European explorers had seen and calculated my position by measuring the
    height and direction of the sun, just as they had. attempted to do. The mariner's guiding stars in
    the southern hemisphere are Canopus and the Southern Cross. These stars played a vital road in the
    extraordinary story I was to uncover, and without the experience of astro-navigation I had gained in
    the Navy, this book would never have been written and the discoveries I made might have remained
    unrecognised for many more years."
    
    I understand that Rorqual was one of Britain's nuclear submarines. That's rather worrying, in the
    light of what follows.
    
    There's stuff in the book about ancient mapping, history and legend, ancient records from China and
    from other parts of the world. I don't claim any knowledge about those topics, so am unable to
    comment on whether Menzies book is well-grounded in those respects or not, (though I have my
    suspicions). However, with other Nav-l members, we know enough between us to evaluate Menzies'
    claim, above, to expertise in astro-navigation and nautical astronomy. I will confine my
    observations to such matters. And we will find that Menzies falls woefully short.
    
    Let's work our way through the book, picking out what seem to be navigational and
    astronomical errors, and you can form your own opinions.
    
    =======================
    
    We can start by returning to that quote on pages 36, "calculated my position by measuring the height
    and direction of the sun". Measuring the height, yes; but the direction? Really?
    
    Page 91. "In Chinese astronomy, latitude was determined not by the distance north of the equator but
    by the distance from the North Pole, which was determined by the altitude of the Pole Star, Polaris.
    A bright and easily identifiable star, Polaris sits directly above the North Pole, billions of miles
    out in space. When viewed from the North Pole it is directly above the observer at 90deg altitude or
    90deg latitude, at the equator it sits on the horizon at 0deg altitude or 0deg latitude. ...since
    Polaris is due north it enables magnetic variation...to be determined. ..."
    
    All that may be (roughly) true today, but not in 1421, when Polaris was 4deg away from the Pole.
    There wasn't then, really a good pole star, though Polaris was the best. But if latitude had indeed
    been defined that way by the Chinese, by the "altitude of the Pole Star", then the latitude of every
    point on Earth would swing through a range of 8deg, over each 24-hour period; surely an impractical
    arrangement. Perhaps it could have been defined in terms of Polaris' maximum altitude (when on the
    meridian), but for half the year that was unobservable if it happened in daytime. It was a problem
    that faced Western navigators also, who had their own "rules" for resolving it.
    
    Page120 reads, referring to navigation in the south hemisphere- "They could use the Southern Cross
    for direction, for they knew that its leading stars, Crucis Alpha and Crucis Gamma, pointed to the
    South Pole ..."
    
    Several misunderstandings here. First; in 1421, that line was 6deg away from the direction to the
    South Pole in the sky (someone check that, please). Second; even if those stars had marked a precise
    line to the Southern pole of the sky, that wouldn't determine where that pole was (in the absence of
    a star to mark it). Third; even if so, the line between those two stars wouldn't establish a
    North-South
    direction on earth (which Menzies seems to be looking for), except when they were on the observer's
    meridian. At other times, that line pointed in quite different directions, as azimuths across the
    Earth's surface. 6 hours earlier or later, the line between them would point East-West. And those
    stars were only visible on the meridian at certain times of the year (when it happened to be night
    then).
    
    Page 161. "The Chinese needed a star in the southern hemisphere to replace Polaris in the northern,
    and in the event they selected two: Canopus for latitude and the Southern Cross for navigation."
    What can "the Southern Cross for navigation" mean?
    
    Continuing- "Canopus ... sits in space three hundred light years from Earth towards the South Pole".
    It's nowhere near the South Pole, with declination about 52deg S.
    
    "To use Canopus for latitude, the Chinese had to determine its precise position by sailing to a
    point directly underneath the star." Why on Earth should that be necessary? It's a matter that crops
    up again and again, underlying much of the book. It seems utter nonsense. Menzies goes on about this
    on the next page, referring to a supposed Chinese visit to the Falklands so that "... the Chinese
    cartographers were nearly underneath Canopus. They were taking such pains to fix their position so
    that they could calculate their precise latitude 52deg 40' south."
    
    He refers (page 162) to the Falklands as an "anchor point, selected because they are not only
    underneath Canopus but also almost exactly half the world away (179deg) from Beijing. At this stage,
    although the Chinese could not measure longitude they knew the earth was a sphere. Moreover, by
    using Polaris they could determine the semi-circumference of that sphere (180deg x 60 nautical
    miles) and thus approximate when they were half the world away from Beijing (days multiplied by
    average speed). If a fleet sailed westwards from this anchor position in the Falklands and found
    another island south of Australia at 52deg 40' South, the cartographers could chart that continent
    by triangulation precisely as they had charted Patagonia."
    
    What's the relevance, if any,  of "half the world away"? Where, I wonder, does any "triangulation"
    come in here? He appears to be proposing to evaluate longitude of Australia (with reference to
    Beijing) by calculating dead-reckoning for travel all the way westward round the globe, and then
    calling it "triangulation".
    
    On page 170, Menzies claims that a section of the Chinese fleet travelled, rather by accident,
    through the Magellan Strait! As they entered a bay, just south of Cape Virgines ... "a ferocious
    current running at up to six knots would have dragged his fleet south-westwards through the strait
    like water down a plughole. By the next morning, the fleet had been sucked halfway through the
    strait. ..." That's an absurd picture; Menzies doesn't realise that the current is a TIDAL one. So,
    after a displacement of up to 24 miles or so in one direction, comes an equal-and-opposite tidal
    displacement back the other way. The Magellan Strait involves a passage of the best part of 300
    miles, yet Menzies makes the absurd claim that a fleet of junks could travel halfway through in the
    course of a single night.
    
    Page 178 refers to " bearings obtained from the constellation of the leading stars of the Southern
    Cross and the latitude of Canopus, both of which become circumpolar- never rising and setting and
    visible in the sky at all times- below 68deg S." Actually, that limit is less than 40deg S.
    "Visible in the sky at all times"? Only at night, surely, so over part of the year it would be
    impossible to observe meridian altitude of Canopus. To avoid that question, he
    continues- "The intensity of its light and the clarity of the Antarctic air often make Canopus
    visible in daylight". This seems a dubious claim, with naked-eye observations (presumably theChinese
    had no telescopes then). Is such a thing possible? Does anyone have experience?
    
    Page 355. The Chinese were supposed by Menzies to have rounded Greenland's North Cape, when they
    "would have been just 180 miles south of the North Pole, for its position in 1422, as determined by
    Polaris at 90deg altitude ... was well to the south of where it is today" That's a nonsensical
    concept. Yes, because of precession, Polaris was then several degrees away from the Pole. But if the
    "Pole" was defined by the position of Polaris, it would have to make  a daily circuit round the
    earth at a latitude of about 86deg north, like Polaris did then. There's just no way of redefining
    the Pole bymoving it toward Greenland. The pole's shift since 1421 is measured in metres, not miles.
    It was no nearer to Greenland in 1421 than it is now.
    
    Page 393- "The Arabs had discovered that the sun's declination, when subtracted from its height at
    midday, gave the latitude of a place in the northern hemisphere". Not so, of course; you need to
    subtract it from the zenith angle.
    
    On page 599 is the statement that for tropical East Africa, 20 nautical miles corresponds to twenty
    seconds of time (it's more like 80)
    
    =============
    
    Those are no more than a selection from the navigational and astronomical errors in Menzies' book.
    I've found at least as many again, that could have been included. And there will be more that I've
    missed, that any competent Nav-l member will be able to pick out.
    
    So if Menzies claims to have been a professional navigator, and gets so much wrong, how accurate
    will be his cartography, his history, his geography, his folklore, his DNA evidence? Menzies' claims
    for the Chinese voyages are, in every sense, fantastic, and lack hard evidence to back them up.
    
    More worrying still, does this same degree of navigational incompetence apply to the present
    generation of commanders of Royal Navy vessels? If so, we have to be grateful for the existence of
    GPS...
    
    George.
    
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    

       
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