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Navigation &
Cartography in the Age
of Discovery
26th January 2017
The Iberian Worldview c 1500
• Medieval society
• Spain & Portugal competing
to reach The Indies
Muslim block across the eastern Mediterranean
• Crusading zeal
• Search for Prester John
• Converts to the true faith
Challenges facing Explorers in Age of Discovery
What did they know of world?
What maps existed to guide thinking?
Who was going to pay for these adventures?
Did suitable vessels exist?
What experience of deep oceans?
Things we know
we don’t know
Things we don’t
know that
we don’t know
What we know
that we know
What we’re unaware
that we actually
do know
Extent of Africa
Location of Spice Islands
Eurasia
Existence of America,
Australia & Antartica
Mediterranean
Western Europe
North Africa
Earth is spherical
Size f the world
Cartography
Mappaemundi
Portolan Charts
Mediterranean-centric
Claudius Ptolemy, 1474
Martin Behaim’s Terrestrial Globe
Columbus’s compounding errors
Circumference of the earth
confused units between roman & arabic miles
30,200 kms instead of 40,000kms
Size of Eurasia
225o instead of 130o
Existence of islands off the coast of Cathay
inc mythical Antillia
Consequence:
estimated voyage from Canaries to Cipangu (Japan) as
4,000km, instead of 18,000
Dividing the World Between Spain & Portugal
• Two treaties (north - south)
• Tordesillas 1494 (east - west)
• Spanish sphere 370 leagues west of
Azores
• Portuguese everything to the east
• Granted sovereignty over land and sea of
undiscovered lands
• Sovereignity (imperium) not ownership
(dominium)
• Portuguese negotiated initial line westward
Portuguese geopolitical
heist?
Naval Architecture
Portuguese Caravel
approx 20m x 6m
Two masts
Latteen-rigged
shallow draft, manoeuvrable
max 300 tonnes
Capacity 20-30 crew
Spanish Carrack (Nao)
approx 30m x 6m
Single deck & three small masts
One aquare sail & two lanteen
shallow draft (3m)
100 - 300 tonnes
Capacity 40 crew
Experience of deep ocean sailing limited to the Atlantic
The First Circumnavigation Sept 1519 - Sept 1522
By MesserWoland and Petr Dlouhý CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)
Progress of Exploration
1434
1423
1492
1488
1498
1511
1542
1482
1521
1470
1500
Development of Portuguese Deep Ocean Navigation
Boxer 1969
World Map 1550