Tag Archives: cartography

Does this projection make my continent look big?

 I drew this version of Ptolemy’s map showing only the longitude lines. He drew them curved to give you the idea that the world is round.

A challenge navigators faced when reading a flat map of the round Earth is that as the meridians—the longitude lines—got closer to the north and south poles they kind of bent around to simulate the round globe. That’s a problem if you’re trying to chart a course. The meridians and parallels don’t meet at right angles so you need to keep adjusting your calculations about where you are…it’s a hot mess.

Gerard Mercator devised a way to mathematically flatten the globe. He imagined a flat map wrapped like a cylinder around the globe. So far, so good. But as you bend the top and bottom of the map to wrap the globe, they get all bunched up, right? There’s too much paper. So he trimmed some paper off the top and bottom, leaving strips that are wide at the Equator and pointy at the poles. These strips are called ‘gores’ in the cartography business.

Without Mercator, with Mercator.

You can do two things with these gores when you flatten them. One is to leave them as they are, with blank space in between the pointy ends. The other is to fill in the blank space in between the pointy ends with more map. Mercator did that— and he straightened the meridians and drew the continents to fit the new coordinates. The result is that you can use the latitude/longitude lines to chart a course that will be perfectly accurate.

Of course, the land and ocean at the top and bottom get stretched out on Mercator’s projection. That makes sense, because what had been a dot (the pole) has been stretched out across the top or bottom of the map.

Recently, some people have complained that on Mercator’s map, the continents closer to the poles appear to have more land mass than the continents near the Equator. That appearance has caused the residents of the equatorial countries to feel bad about their land mass.

The Western Civ User’s Guide staff is here to help. If you’re feeling bad about your land mass, call 1-800-IFEELBADABOUTMYLANDMASS and talk to one of our concerned and sympathetic counselors.

https://www.vox.com/2015/3/5/8151303/gerardus-mercator-maps
https://www.businessinsider.com/mercator-projection-v-gall-peters-projection-2013-12

https://www.britannica.com/science/Mercator-projection

Here’s a great old video of how globes are made. https://www.youtube.com/watch?v=4RWcWSN4HhI
Notice how when they paste the map onto the globe, the map is cut into sections called ‘gores’—pointy at top and bottom, wide in the middle.

http://gallery.lib.umn.edu/exhibits/show/maps-and-mapmakers–martin-wal/about_the_exhibit

Here’s the amazing 17-year-old Leslie Gore, who is not a section of a map. https://www.youtube.com/watch?v=RjdH_NmmO0I

Back to the beginning of The Western Civ User’s Guide to Time & Space

Maps for everybody

Printing presses had been around for a while, but printing really took off after Gutenberg invented moveable type. Printing presses can generate many images on paper very quickly compared to drawing each one by hand. Suddenly ordinary people could afford to own books—and navigators could afford to have maps when they sailed.

The first printed maps were woodcuts—what’s called relief printing. This is when you take a flat piece of wood and trace the drawing onto it backwards; you carve away everything that isn’t the drawing; you roll ink onto the wood and press it onto a piece of paper; the ink leaves an impression on the paper. Showing longitude & latitude lines on a woodcut map wouldn’t be easy, because you have to carve wood away leaving the line.

Much better for accurate mapmaking was engraving. With this kind of printing, you take a flat piece of copper and draw lines onto it with a steel stylus. Steel is much harder than copper, so the stylus cuts a precise, v-shaped groove. When the drawing is finished, you rub ink all over the copper plate and into the grooves. Wipe the surface clean and leave the ink in the grooves. Run the copper plate with a damp piece of paper through a tight press and the ink stays on on the paper.

When the paper dries, you can feel the ink lines—they stand up. American paper money is engraved. You can feel the lines on a brand-new dollar bill. Copper is durable so you can make gazillions of copies from one plate.

https://www.juliantrubin.com/bigten/gutenbergmovable.html

https://www.britannica.com/biography/Johannes-Gutenberg

Back to the beginning of The Western Civ User’s Guide to Time & Space

The Equator

Human brains are marvelous. Something we humans are able to do is look at a round object, like the Earth, and draw it flattened out as a map. Then, get this: other humans are able to look at the flat map and comprehend a round Earth. Yay, us!

Ptolemy was the first to think of drawing lines of longitude and latitude on a map. Longitude lines travel from north to south poles. Latitude lines travel east to west and are parallel to the Equator. Together they make a grid on a flat map. Longitude and latitude lines are man-made; they don’t exist except on maps. Longitude and latitude lines are the way we organize the Earth’s surface so we can navigate on it. You assign the lines names or numbers.

Latitude lines (also called parallels) are circles that run around the circumference of the Earth and are measured in degrees. The Equator divides the Earth into northern and southern hemispheres (hemi = half, sphere = globe). It’s at 0 degrees. The North & South poles are at 90 degrees.

Back to the beginning of The Western Civ User’s Guide to Time & Space

Amerigo

The next guy to visit the New World was Amerigo Vespucci (vess-POOCH-y) from Florence, Italy. Amerigo was a navigator, a mapmaker, a trader and astronomer. During one of his trips he calculated the circumference of the Earth (how big around at the Equator)—and was off by only 50 miles!

Amerigo Vespucci was also a writer and promoter. If Columbus didn’t realize how big the New World is, Vespucci surely did. He wrote pamphlets (short, easy-to-read) to tell people about the New World and all it had to offer. Vespucci promoted the New World to Europe. Promotion, gang. Amerigo Vespucci did such a good job of promoting the New World that a German mapmaker named the newly-discovered continents for Amerigo—North America and South America—and it caught on.

It’s a tradition to name continents in the feminine form—Asia; Africa; Europe (Europa to the people who live there); India; Australia; Antarctica. So the boy’s name Amerigo became the girl’s name America.

How do people promote nowadays? Writing a pamphlet was the way to go in Vespucci’s time. How would you promote something big that you wanted everybody to know about?

Maps, we need maps!

As we’ve seen, Venice was hopping with trade on the Mediterranean Sea and beyond. With their compasses and astrolabes and lightly-built galleons, Venetian traders traveled all over the known world. Likewise, traders from all over the world stopped in Venice. Compasses work best with a map, so Venice’s map-making (cartography) business was booming.

In ad 1450, in a monastery in Venice, there lived a monk named Fra Mauro (Brother Mauro). Fra Mauro was an extraordinary cartographer and his map is the one you see pictured here. It’s about 6 feet across.

It’s not easy to recognize all the continents right away, because he drew it with North at the bottom. We’re used to seeing North at the top of maps. I’m not sure when it became standard practice to put North at the top. Over at the extreme right, you can see a little compass-rose with North pointing down. As you work your way left from there, you’ll see Spain and Portugal, the Straits of Gibraltar where Europe almost touches Africa, and the Mediterranean Sea where the boot of Italy is kicking up rather than down. The shapes of Africa and Asia are difficult to recognize, too. It would be a while before cartographers could accurately survey land masses. Africa is in the upper-right. Asia takes up almost all the the left half of the map.

The New World—the Americas and Australia—hadn’t been discovered yet.

Here’s an article about Fra Mauro, with some close-ups of his map.