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Thursday, April 14, 2011

Junk Navigation

So, here's the setup.

I happen to teach navigation for a living. It happens that for the past few weeks I've been teaching a course called "Emergency Navigation", which is mostly an advanced celestial navigation class, focusing largely on navigating by the night sky without a sextant, chronometer, or almanac.

One of my co-workers at my other "office", which happens to be a high-speed passenger ferry, knew that I was teaching that class, and so kindly loaned me a book he had read which he thought I might be interested in. The reason he thought I'd be interested was that the book explained how 15th century Chinese navigators had utilized the stars to determine longitude without a chronometer. Coolness.

So, the book turns out to be Gavin Menzies' 1434: The year a magnificent Chinese fleet sailed to Italy and ignited the Renaissance.

Conveniently, the title of the book alleviates the necessity for any further description of the content.
Before I continue, here are my disclaimers:

1) I am not a historian.
2) I do not speak any more Mandarin or Cantonese than any other American sailor who occasionally makes port calls in either China, or any other American parent of a child who watches Sagwa: The Chinese Siamese Cat on PBS Kids.
3) I do not have an opinion about whether or not the Chinese followed Marco Polo back to Italy.
4) I do not have an opinion about whether the Chinese "discovered" the Americas earlier than the Italians did.
5) I have no opinion regarding Menzies as a historian. Others seem to.
6) I have not actually read all of the book yet, or any more than the two chapters which specifically deal with navigation. I only started it this afternoon.

My interest is exclusively in his claims that the Chinese somehow were able to determine longitude from the stars without a chronometer. I was skeptical, but intrigued. It turns out that I was right to be skeptical. Menzies claims to have been a navigator on submarines. If this is true, he really, really sucked at it.

Menzies states that in order to determine latitude the Chinese navigators measured the altitude of Polaris above the horizon. That's oversimplified, but almost certainly true. So far, so good. He continues with the oversimplification that Polaris is at true north, which isn't quite true (and was rather less true in 1434 than it is today due to precession), but I'm willing to roll with it for the sake of argument.

Then, to derive longitude, they measured either a star which was at the same azimuth as Polaris, or else had a right ascension (or sidereal hour angle, Menzies doesn't seem to understand the difference) of 90 degrees east or west of Polaris. Because 90 degrees east or west of true north

Okay, so that can't work. But if you know that star X is directly below or above Polaris at exactly midnight in Nanjing, and at the exact same time star Y is directly above or below Polaris at your own location at the time of midnight in Nanjing, then you know that you are X number of degrees east or west of Nanjing! And, the way we know that it's midnight in Nanjing without a chronometer is... um... because... crap.

It actually gets worse (much worse) than this (Polaris is a star, so Poseidon must also be a star, along with Trident and Tomahawk!), but at that point I started getting embarrassed first for the author, and then for the entire Royal Navy which presumably trained him, and then for submarine sailors everywhere who would be thought mentally deficient by association.

Yes, it's that bad. At least the navigation portions are. I haven't read the rest, and even when I have I don't feel qualified to judge his scholarship as a historian. His premise is that by 130 years after Marco Polo returned from China, Italy had had contact with China which influenced the Renaissance. I don't think many historians would disagree with that premise. Whether or not China also ventured west to Italy after that time is interesting but not especially relevant to the conversation.

But I have to genuinely question the veracity of his claim to have been a navigator aboard her majesty's submarines. I've sailed with the Royal Navy, they are very sharp sailors and very, very competent submarine drivers. For someone to claim to have been a navigator for them and to simultaneously have so little grasp of such a basic concept as longitude stretches plausibility to the breaking point.


  1. So the Chinese didn't solve the longitude problem 300 years before Harrison?

  2. Well we are loggerheads on this!! I am a believer of Menzies and his theories. His Royal Navy service is a given, no question there. Since the books were written there has been considerable research done in China by some of the schools that are training personnel for both naval and civilian vessels. Together this adds support to many aspects of Admiral Zheng He's voyages and Gavin Menzies. See Shi Lang in NAUTICAL LOG just today. Read on!!
    Good Watch.

  3. Further point on Zheng He and Chinese navigation. They considered the principal point of the compass rose to be South. Their charts were strip charts viewing and drawing the coastline from seaward in elevation. The British Victorian era hydrographers did the same and on the older Admiralty charts there are sketchs of the shoreline as a Watchkeeper would see from about ten nautical miles off. On my study wall I have BA Chart 2049 Kinsale to Wexford 1890 edition. Virtually the entire coastline is shown including at 7° West the entrance to Waterford Harbour, my birthplace. These are the waters I learned to navigate in with just a magnetic compass, binoculars and tide tables at age 14 working Summers in local fishing boats 50 to 75 feet overall length. Best navigation school I ever attended.

    Good Watch.

  4. Zheng He may well have sailed to Italy and/or the Americas. He may have also had a means of deriving longitude without a chronometer, such as lunar distances. He might even have simply been very competent at dead reckoning. But he most emphatically did not derive longitude from the stars in any of the ways that Menzies describes. And yes, I would expect that a deck officer in the Royal Navy, even on submarines (as I was), would have a solid enough understanding of the concept of longitude to realize why this is true.

  5. Agreed that the Chinese oriented toward south. Ironically, my 11-year-old is proudly displaying a replica of a Han dynasty spoon-compass she made in a mock-Chinese History museum at her school today.

  6. I'm not an historian either, but it looks like those who are have very few kind words for Menzies. This from a quick search on Wikipedia:

    "In the community of professional historians these theories are dismissed as fictitious and have received no support as of this writing."

    "In 2004, historian Robert Finlay severely criticized Menzies in the Journal of World History for his "reckless manner of dealing with evidence" that led him to propose hypotheses "without a shred of proof."

    "Unfortunately, this reckless manner of dealing with evidence is typical of 1421, vitiating all its extraordinary claims: the voyages it describes never took place, Chinese information never reached Prince Henry and Columbus, and there is no evidence of the Ming fleets in newly discovered lands. The fundamental assumption of the book—that Zhu Di dispatched the Ming fleets because he had a "grand plan", a vision of charting the world and creating a maritime empire spanning the oceans—is simply asserted by Menzies without a shred of proof ... The reasoning of 1421 is inexorably circular, its evidence spurious, its research derisory, its borrowings unacknowledged, its citations slipshod, and its assertions preposterous ... Examination of the book's central claims reveals they are uniformly without substance."

    "His book 1421: The Year China Discovered the World, is a work of sheer fiction presented as revisionist history. Not a single document or artifact has been found to support his new claims on the supposed Ming naval expeditions beyond Africa...Menzies' numerous claims and the hundreds of pieces of "evidence" he has assembled have been thoroughly and entirely discredited by historians, maritime experts and oceanographers from China, the U.S., Europe and elsewhere."

    "Felipe Fernández-Armesto, a professor of history at Tufts University in the United States and at Queen Mary, University of London, examined Menzies claim that private papers of Columbus indicate a Chinese ambassador in correspondence with the Pope, and labels this claim as "drivel." He states that no reputable scholar supports the view that Toscanelli's letter refers to a Chinese ambassador."

    Martin Kemp, Professor of the History of Art at Oxford University questions the rigor of Menzies' application of the historical method and, in regard to European illustrations purporting to be copied from the Chinese Nong Shu, asserts that Menzies "says something is a copy just because they look similar. He says two things are almost identical when they are not." Further, Taccola started work on his treatise as early as 1419 and essentially completed it in 1433, one year before the supposed arrival of the Chinese fleet.

    "Geoff Wade, a senior research fellow at the Asia Research Institute of the National University of Singapore, acknowledges that there was a cross exchange of technological ideas between Europe and China, but ultimately classifies Menzies' book as historical fiction and asserts that there is "absolutely no Chinese evidence" for a maritime venture to Italy in 1434. Wade criticized Menzies for repeated presentation of "fabricated evidence", including a faked map, in a quest to gain maximum media attention for his hypothesis."

  7. Careful you will seriously p-o the Chinese and they hold a good portion of the US National Debt!!! Even RR's daughter is being trained in Chinese history of the Han dynasty. I would supect that Menzies as taken quite a few liberties with history. One of my Jesuit history teachers at Clongowes Wood College told us there are three versions of history, our view, their view, and what really happened. So who can say that there is not some professional jealousy on the part of the history professors quoted. As to Geoff Wade he is not above suspecion himself so not for me a good quote. Do all NASA engineers agree with each other? If we do not question how do we learn the truth?

    Good Watch.

  8. National Geographic also seems to think the maps are fakes, and that Zheng He did not voyage further abroad than the east coast of Africa. Which is still a substantial achievement, in his day.

  9. I also agree with Peter, that all history is fiction. Some of it is more fictional than other. In this case, I really have no opinion or knowledge. My gripe was (and still is) with Menzies' navigation. The historical stuff is frankly above my paygrade.

  10. Oh, and yes, my daughter is learning Mandarin in middle school. But given that Seattle is a Pacific Rim seaport, maybe that isn't altogether unusual. Needless to say, I don't attempt to help her with her Mandarin homework.