Maps and Mystery

[Audible Click]

I came across an article in the newspaper today and thought I'd share it with any forum members that are as fascinated with cartology as I am. It seems that some of the ancient maps/charts still mystify researchers due to their uncanny accuracy.


John Hessler Senior Cartographic Librarian in the Geography and Map Division of the Library of Congress has been combining fieldwork with historical data and epigraphic evidence, along with the latest GIS computer technology.


John Hessler, mathematical wizard and the senior cartographic librarian at the Library of Congress, slipped into the locked underground vaults of the library one morning earlier this week.

Slim, handsome, intense, bespectacled, Hessler approached a priceless 1559 portolan chart on the table before him, sketched in the hand of Mateo Prunes, the Majorcan mapmaker. The nautical map of the Mediterranean and Black seas is inked onto the skin of a single sheep.

It is a rare representative of one of the world's greatest and most enduring mysteries: Where and how did medieval mapmakers, apparently armed with no more than a compass, an hourglass and sets of sailing directions, develop stunningly accurate maps of southern Europe, the Black Sea and North African coastlines, as if they were looking down from a satellite, when no one had been higher than a treetop?

Complete article here:

http://www.washingtonpost.com/wp-dyn/content/article/2010/05/21/AR2010052104713.html

 

[Bell]

Thanks for the link. Amazing map. I love looking at maps, especially old and / or historical maps.

I have no idea how those medieval maps were made so accurate in that time. But I think refinement was part of the process. Draw a map and then get more and more detail in over time.

 

[Spindrift]

Obviously, it was ancient astronauts. I'm surprised the History Channel hasn't jumped on this. If you can work some ghost loggers into it, they could make a series out of it.

Then again it's real history and cool but requires a little thinking so I'm not holding my breath.

 

[MG1962]

Thanks for the link. Amazing map. I love looking at maps, especially old and / or historical maps.

I have no idea how those medieval maps were made so accurate in that time. But I think refinement was part of the process. Draw a map and then get more and more detail in over time.

Well I think there is a bit of hyperbol in the article. The oldest maps date over three hundred years before this one

 

[Hokulele]

I would need to see the maps in question and the calculations in more detail, but I would guess that the accuracy lies mostly in latitude and not in longitude. Calculting latitude based on celestial navigation is relatively simple and surprisingly accurate. If they were using sailing times between known ports, longitude can be calculated fairly close, but would get much worse when entering unknown waters. Dava Sobel wrote a wonderful book on this subject.

http://www.amazon.com/exec/obidos/ASIN/0140258795/

Regarding mapping and accuracy, a lot of that depends on what you find to be more relevant, distance or time of travel. The navigators who plied the Micornesian waters made maps out of sticks and shells. Early Western historians sneered at these maps for being woefully inaccurate. Once they realized that the spacing represented travel time, currents, and trade winds, they were forced to change their judgments dramatically.

 

[Loss Leader]

The amazing thing to me isn't that sailors developed accurate maps - after all, their lives depended on it - but that this knowledge had such a hard time finding its way to the general population in any form. Hundreds of years after sailors knew that Italy was a boot, most non-seamen thought of it as pretty rectangular. I read a book about it recently.

 

[tazjet]

There have been some pretty ancient and encrusted astrolabes recovered from antiquity haven't there?

If ancient people had a concept of using angles of declination of the sun or stars then they had to also have a 3 dimensional concept of the sperical nature of the earth and if my rusty brainbox serves me correctly hadn't Pythagoras already calculated the circumference of the earth from the height of a shaddow from a stick?

 

[ingoa]

I believe you meant Erosthenes.

 

[Jeff Corey]

Pythagoras is generally credited with the theory but it was Eratosthenes who calculated the Earth's circumference using the shadows cast by the sun during the summer solstice at different locations.