Replies

As long as you sight those stars all the way on the return voyage, you will hit Asia. Their massive ships could have easily supplied the crews for long voyages. It's that simple.

Sorry but its not. That's why so few cultures were able to master sailing in the open seas (no coast hugging) and returning home to the exact place from which they started.

If you don't have a calendar, you don't have an ephmeris.
If you don't have an ephmeris, you can't figure out where you are.
If you can't figure out where you are, you can't get back.

Thanks for the debate. We'll just have to agree to disagree. Chinese astronomy in 1650 was incapable of this kind of sophisticated open sea voyage using stellar navigation. The Chinese certainly didn't practice it in 1295. Therefore, it is unlikely (as I wrote in my first post) that the Chinese acquired all the knowledge of the heavens by 1400 (an item claimed by the author) to outperform navigational feats of the Vikings only to lose that knowledge by 1650.

I will add this in closing: The Vikings certainly had no ephemerises. I have no understanding why you contend that they were more advanced than the Chinese in navigation. The government scientists of China of 1650 may have not understood navigation but that doesn't mean that the common seafaring merchant didn't either. I have never heard of any navigational expert claim that you can't traverse oceans without an ephemeris. Good Day.

"Sorry but its not. That's why so few cultures were able to master sailing in the open seas (no coast hugging) and returning home to the exact place from which they started.

If you don't have a calendar, you don't have an ephmeris.
If you don't have an ephmeris, you can't figure out where you are.
If you can't figure out where you are, you can't get back."

Hmmm. . . someone forgot to tell the Polynesians that, I guess. They managed some impressive feats of navigation without an ephemeris. In fact, without a compass. Probably the most primitive open-ocean sailors in history.

Actually, according to your assertions Columbus could not have crossed the Atlantic. He did not return home to the "exact same place" from which he started, as his return voyage was considerably north of his outward voyage. (He wanted the wind behind him. So you take a southerly track out, catching the trades, and a northerly track back, catching the westerlies.

The point-to-point navigation of which you speak did not exist much prior to the mid 19th century. Columbus, Magellan, Cabot, Drake, et al, pretty much used navigational tools and techniques that were virtually identical to those available to the 14th and 15th century Chinese -- log line, quadrant, sand glass, and compass. In fact, Columbus really did not use a quadrant well. He mostly depended upon log line, glass, and compass, and generally made a hash of it when he tried to do celestial navigation.

The real reason that there was so little deep-sea navigation was less navigation limitations as lack of destinations. Look at maps of civizations prior to 1500 (European, Arab, Indian, Chinese, and Amerindian). What open-ocean routes are commonly taken.

Among the Europeans, there were only two. A day-sail across the North Sea, or a voyage from the Basque or Breton coast to the Grand Banks. (Yup, those primative fisherman, without even an ephemaris.)

The Arabs and Indians shared one -- sailing from the Horn of Africa to India on the monsoon winds.

The Chinese? The Pacific is mighty wide, and there isn't much of value on the other side. Although Cheng Ho did cross open ocean on his voyages between Africa and India.

The main reason open-ocean travel became common after 1500 has nothing to do with technology, and everything to do with economics. New Spain, New France, and New England provided an incentive to cross open ocean that was absent previously.

And I think you are underestimating the Chinese. They were considerably more sophisticated -- at least their seagoing technology -- than the Europeans of the 14th and 15th century. I don't think they circumnavigated the globe, but I would not be surprised if they doubled the Cape of Good Hope.

You might want to read Ma Huan's "Ying-Yai Sheng-Lan" (The Overall Survey of the Ocean's Shores). It documents the Cheng Ho expeditions. An English translation was published by the Hakluyt Society (London) in 1970, with a reprint by the White Lotus Co. (Bankok) in 1997. It should be available through interlibrary loan.