NavList:

Andrés,

What's the "back story" on this article? Are there people suggesting that there were significant applications of longitude by lunars in the early 16th century? Who's making these claims, and how is this story being told?

You linked to the Wikipedia article on Elcano which includes this note:
"... it is known that Elcano owned two books written in Latin, indicating that he knew how to read that language. Both books refer to astronomy, one being the Almanac of Regiomontanus, which allowed navigators to determine longitude at sea with observations of the moon."

Of course that's an extreme exaggeration. Is this the problem?

Of the article by R. Gaspar apparently disputing such claims (is that right?), you noted:
"I have attached the file, because it is usually no longer available after a while."

First, that you for including it. That's now archived safe and sound in the NavList archive and will remain so, unless there is a copyright claim against its presence there. Could you elaborate a bit on what you've said here? Do you mean that this specific article by Gaspar is disappearing from that cambrdige.org archive "after a while"? What do you think is going on there? The article itself looks quite sensible. I have only skimmed it so far, and of course, the "suspense was killing me" so I read the conclusion. He seems to have made a good case that the apparently accurate lunar longitudes were only random chance resulting from fortuitous cancellations of errors. But in general the so-called "lunars" were every bit as poor as we would expect. This should call to mind the old aphorism which says that a stopped clock correctly displays the exact time twice a day.

There were other attempts by navigators long before lunars were practical that at least gave the thing a try. They're barely remembered because they were failed experiments. While those navigators deserve a footnote in our histories of navigation, and such experiments surely inform us that there were smart people out on the seas, well versed in the astronomical concepts that would become the foundation of future scientific navigation, they were not magicians. Without decent models of the Moon's motion --which did not exist until the late 18th century-- and without instruments capable of measuring angles accurately to the nearest minute of arc reliably and regularly --which did not exist until the middle of the 18th century--, all such experiments were doomed to fail. Now and then, by luck, you get a case with an unusually small error, but that's like winning the lottery. People do win lotteries, but they're not a good investment plan!

As I say, so far, I have only skimmed the article, so I'm just writing in general terms here.

Frank Reed