

Library of Congress holds conference on origins of portolan charts - andrewljohnson
http://www.washingtonpost.com/wp-dyn/content/article/2010/05/21/AR2010052104713.html

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Maciek416
John Hessler's blog, where he actually discusses methods for the cartographic
analysis mentioned in the article, can be found here:
<http://warpinghistory.blogspot.com/>

Here's a sample map made by the mapmaker Mateo Prunes (3200x1800):
<http://fglorente.org/zen/albums/mapas/Mateo%20Prunes.gif>

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anigbrowl
Thanks for this. It's really quite astounding how good ancient cartography
was, given the limitations. For all that we live in very exciting times today
- and can communicate in almost real time to discuss such subjects - how
thrilling, and slightly scary, it must have been to live in those times and be
among the few to have a firm grasp on the fundamentals of science and the
natural world.

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andrewljohnson
My title was originally "Accurate map from 1275." Thankfully, some truly
meddlesome mod took all meaning from the title and instead used the hackneyed
print headline that was no doubt written to fill a certain space in a
broadsheet.

I don't know about the rest of HN, but I had no clue what a Portolan Chart was
until I read this article. My re-titling was intentional and I would imagine
helped get the article to the front page.

Stop meddling or I am going to stop contributing. I understand there are times
when a title is misleading or goes against guidelines, but this change is just
a mod on a power trip.

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lkozma
The article speculates about Roman or Phoenician maps that might have been
lost, but makes no mention of the more probable Arab influence. This is just
my naive guess, but wasn't Arab mathematics and astronomy the state-of-the-art
of the time and also probably Arabs had the most detailed information about
the mediteranean region at that time.

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jackfoxy
The Arabs at the time had preserved a good portion of the scientific
researches of the Ptolemaic Greeks, who were able to determine latitude (and I
think longitude somewhat with many astronomical observations over time), so
the relative locations of some key ports may have filtered out to some
European cartographers at the time. The ability to observe latitude was
possibly seeing limited re-discovery in Europe through Arab sources. For sure
by the early 15th century Portuguese navigators could easily observe latitude.

But I believe these maps were created through dead reckoning.
<http://en.wikipedia.org/wiki/Dead_reckoning> William Clark created a
meticulously detailed highly accurate map of the Missouri, Snake, and Columbia
rivers through dead reckoning, with the aid only of compass and sextant for
latitude. (Lewis & Clark made some detailed observations for longitude, but
the calculations were not performed until after the expedition was over and
had nothing to do with Clark's map.)

I'll bet these maps originally had nothing to do with normal navigation (i.e.
for commerce) accurate maps were for a long time military intelligence assets.

Great Britain employed a network of spies employing dead reckoning techniques
to map out areas of south central Asia the British did not have access to (for
military/intelligence purposes). Rudyard Kipling's novel Kim deals with this
historical episode.

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tokenadult
The map most discussed in the submitted article was about contemporaneous with
Marco Polo, who was preceded as a traveler to China by John of Plano Carpini

<http://en.wikipedia.org/wiki/Giovanni_da_Pian_del_Carpine>

(ca. 1180 - August 1, 1252). Early Chinese cartography

<http://en.wikipedia.org/wiki/Early_Chinese_cartography>

was sufficiently good to serve as models for the maps mentioned in the
submitted article, although the time sequence of interchange between China and
the West alone does not prove any Chinese influence on the European maps.

~~~
est
Byzantine Empire sends several ambassadors to Tang China, what map did they
use?

~~~
electromagnetic
They would have likely used a collection of East-is-Up maps to get from
destination to destination. The medieval maps _were_ maps, however they were
designed to allow you to navigate from natural markings as there was no such
thing as a compass, you only had the sun to tell you was going in the right
direction. Similarly many of these maps were point A to point B maps, with the
destination at the top, you found the path it was describing and simply
followed the route.

Notable objects were used to navigate, for instance the Tree of Ténéré is
still frequently drawn on maps as it was the only tree for 200km (now it's
simply a statue to where the tree once was). It was a key marker for trade
caravans.

They would also have likely used a great many of local navigators, as
explorers still do today. Our great explorers were merely bumbling idiots who
got incredibly lucky in finding amazing local explorers who had lived the land
for decades.

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RabidChihuahua
Way cool.

