Take a look at this map, this is Ptolemy’s map of the known world, constructed from his 2nd
century work The Geography. Obviously it’s not perfect, in fact to our modern eyes it
almost looks like an American drew it, but you can see that even back in these ancient times
people knew roughly how the coastlines of the areas around them were shaped.
But… how did the Greeks or Romans or any pre-satellite civilization
work out how the world and the landmasses on it were shaped, and how did they make these maps?
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Maps are arguably some of the best things invented by humanity. Coming in all shapes and sizes,
they tell us not just about the world or universe around us, but how to navigate said world,
how the world is doing, or how we thought of the world at a particular time. Now something at least
I’ve always wondered is how did people in ancient times work out how these coastlines were shaped?
Well, let’s put ourselves in the shoes of the ancient Greeks
and try to figure out how they mapped the world they knew.
So first… where do you start? Well maybe your first instinct will be
to take your map and drawing utensils and sail around all the Mediterranean coasts,
and you could do that for shorter distances, but for longer voyages not only would this be
unnecessary for getting to your destination, there are a lot of reasons why this would be a bad idea:
it would take way too long, it would be incredibly unsafe if you didn’t know what you were doing,
you wouldn’t always know where you were, it would take too long, you could run out of food,
it would take way too long, and just tracing the coastline won’t give you the best result. However,
you could still survey the land around you, and there were many different ways of doing that.
These methods and devices included triangulation (as all you Map Men fans amogus will recognize),
or the groma for building long, straight Roman roads, or rope stretchers measuring
the flooding of the Nile in Ancient Egypt. However these were more often used for
surveying land to build stuff on top of it, and to tax whatever was built on top of it.
So you go to survey the local area and… actually you don’t really need to
Wait then why did you just teach me how to do it? Well someone’s got to do it for certain areas,
but a cartographer’s job is mainly to compile all this data together.
If you were trying to make a map of the known world in an already established civilization,
it’s not like you would have had no prior information to work with. With
traveler’s accounts, navigator’s reports, literature, regional maps, and many other sources,
many an ancient cartographer made these world maps by simply collecting and compiling all this data,
often barely leaving their own hometowns. Anaximander,
a philosopher from the 6th century BC, is credited as having made one of the first maps of the world.
Anaximander however believed the world to be centered on the Aegean Sea,
surrounded by the ocean on all sides, and that all this rested atop a large column.
Eratosthenes, a Greek geographer, mathematician, poet, astronomer, and music theorist
born in 276 BC in Cyrene, famously proved what Pythagoras and Aristotle had theorized prior,
that the Earth was indeed round. Knowing that the bottom a well in the southern Egyptian city
of Syene (not to be confused to Cyrene, which is near the modern Libyan city of Benghazi) would
be illuminated by the Sun twice a year, as the Sun passed directly over it, Eratosthenes measured the
angle the sunlight hit a well in Alexandria at the same time Syene was under the subsolar point, and
using geometry measured the rough circumference of the Earth, and got it almost entirely right.
Having worked out the size and shape of the Earth, Eratosthenes then decided to map it out, or at
least all the parts known to his civilization. Now it’s one thing to know where all the nearby
islands and peninsulas were and roughly how far away they probably were, but just because you know
roughly how you’ll need to turn a ship to hug the Italian coast doesn’t necessarily mean you’ll get
everything completely right, but Eratosthenes had a new way of measuring how far apart everything
was without actually having to measure anything. He invented a system of parallels and meridians,
very much like we use today, creating a sort of grid system over the world. Thus if you
know a place’s longitude and latitude, you can easily place it within the right parallels.
Luckily, he lived in Alexandria and had access to all the knowledge of the Library of Alexandria,
including travel records, meaning there was certainly no shortage of data available to him.
Claudius Ptolemy, born in around AD 100 in Roman Egypt, built on the works of Eratosthenes and
other famous geographers of the time to make his own map of the world. One of his
most well-known works was Geographia, or The Geography, a compilation of all the geographic
knowledge available to the Romans at the time. Like Eratosthenes, Ptolemy used this system
of parallels and meridians to place cities and well-known areas at certain points of the globe,
using data compiled from around the Roman Empire (which there was also
certainly no shortage of) to determine a place’s latitude and longitude. In fact,
none of Ptolemy’s original world maps have survived to this day,
but the instructions for making them have, thus they are still quite easy to reconstruct.
So… how do you determine a place’s longitude and latitude? Well today we might use a GPS, but for
thousands of years we had our own space-based methods of finding where on Earth we were,
and all we really needed to do was look up. Some of the earliest maps for navigation
weren’t maps of the Earth at all, but maps of important constellations. Move over,
Star Trek and Star Wars, there’s a new player in town (that’s actually already been around
for thousands of years) and it’s called star charts! Navigators can use basically anything
that appears in the sky at regular intervals, including the Sun, the Moon, the other planets,
or the stars and the constellations they form. Figuring out your latitude is actually quite easy.
If you’re in the northern hemisphere (as these famous cartographers generally were) the star
Polaris-- known as the “north star”-- could be used to determine how far you were from the North
Pole. Quite a few tools had been invented to help determine one’s latitude, including the astrolabe,
sextant, quadrant, theodolite, or whatever else you have to spot stars and measure angles.
My personal favorite of these tools though has to be the kamal. This 9th and 10th century Arab
invention is literally just a small square piece of wood and a knotted string. The idea
here is that the closer to the equator you are the closer Polaris will appear to the horizon,
and the further north you go the higher up Polaris appears. Thus, holding the string in your teeth,
you measure how far you need to put the board away from your face for the bottom to touch
the horizon and the top to touch Polaris, using the string to record the measurements.
Figuring out your longitude however is a lot harder, because the Earth…
spins… meaning a constellation directly to your east will be directly to your west after only
a few hours without you even moving, giving you no fixed reference points for east or west. Very
inconsiderate of the stars if you ask me! Actually it’s the Earth that spins through
space, the stars are stationary. Well then if the Earth spins,
why don’t we feel it? Because it’s incredibly
subtle on that big of a scale and that’s literally not how any of this works…
Checkmate, Copernicists! Thus in order to track latitude, one
thing you’d need is an accurate clock. Hipparchus in the 2nd century BC proposed measuring longitude
by gathering what times different locations saw solar eclipses. This idea was sound in theory, but
ultimately with the timekeeping technology of the time didn’t seem to go very far. Ptolemy defined
the Prime Meridian as the Fortune Isles, then the westernmost point of land known to the Roman
Empire, though with no good method of measuring longitude other than how long the roads between
different cities were (and the angles they would have taken), the /shape/ of the known world might
have been alright, but he vastly overestimated how wide the world was. That’s not to say the
Romans didn’t have ingenious ways of measuring distance, they most certainly did, but it’s not
like you can just draw a straight line across the known world and know how wide Eurasia really is.
A lot of the process though was often just making assumptions about what the world looked like.
For example since Ancient Greek times it was thought that there would need to be the same
amount of land in the southern hemisphere as the northern, to keep the world balanced.
Thus, a lot of infamous map mistakes had been made, from finding the southern end of
Baja California and assuming the whole thing was an island to noticing every
other continent apparently had a great fertile river and assuming Australia would be the same
way. Hey someone should make a video about that! When the Age of Discovery Update dropped,
not only were different parts of the map unlocked to European explorers,
but new tools were also added to aid in navigation and surveying. The refracting telescope was
invented in 1608 and the pendulum clock in 1657, though the latter saw little use at sea because
ships also move side-to-side, though these provided huge advantages over dead reckoning.
This all allowed for the creation of some of the first true maps of the world.
The Greeks and Romans obviously weren’t alone to the party either, the Arabs and Chinese also made
their own world maps (the former even preserving many of the Greek texts we talked about here),
and the Polynesians used maps made of sticks and seashells, with the shells representing different
islands and the sticks bent and shaped in certain ways to show how the winds and waves flowed.
Now it’s no secret, the precise details on these maps were incredibly inaccurate, but
here’s the thing, before maybe the 17th century, maps were often times more symbolic than specific.
Back then it was mostly whatever says goes. But… did it necessarily matter?
This didn’t really seem to impede Greek colonists or Arab explorers or Phoenician traders. Today we
need our maps to be super-specific for what we do, but the Romans didn’t have satellite communication
or hard fixed borders with their neighbors. Could it be that for these purposes these maps were…
good enough? I mean knowing Italy is curved like this and not like this isn’t necessarily as
important as making sure you know you’re heading towards the right part Italy. Don’t get me wrong
though, those super-oversimplified medieval T-and-O maps are a sin.
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logo again! It’s Skillshare I know Through the amazing courses you
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