say, then, that projection (transferal) results in a projection (flat map).
The diagram that shows the globe and light bulb is a simple model that most people find helpful in visualizing how projections are made. In reality, projections aren’t made with a glowing light bulb in the center of a globe. Instead, projections are products of mathematical formulas, trigonometric tables, and things of that ilk. The specifics are pretty tedious; fortunately, trying to explain it all in language that even I can understand is beyond the scope of this book. It will be sufficient for you to appreciate that different projections exist, but none are totally truthful.
Realizing Exactly How Flat Maps Lie
Cartographers have developed literally dozens of different kinds of map projections over the years. Each one contains some degree of misinformation. If you’re like most people you’ve given little or no thought to map projections nor have you suffered from not doing so. Or have you? (For another perspective on why this matters, see the sidebar “Applied Geography: Putting your best projection forward.”)
Understanding the facts about maps can’t help but make you a better-informed person. Maps are a common means of communicating information. They pop up in internet articles, magazines, books, TV programs, and elsewhere. Because mainstream media is in the business of providing factual information, people may understandably assume that the maps they’re looking at are accurate. But maps that lie flat lie, and there’s nothing anybody can do about it — except maybe understand the nature of the distortions and appreciate that flat maps should be interpreted with a certain amount of caution.
Cartographers know projections lie, so their objective is to get as close to reality as possible. But enough of this blabber about maps that lie, it’s time to consider a practical example that involves some honest-to-goodness maps. Or rather, some not-so-honest-to-goodness maps.
Singapore, please. And step on it!
Suppose you live in New York City and are preparing for a trip to Singapore, almost halfway around the world. In planning your trip, you decide to minimize your flying time and also to stop somewhere for a day or two, just to break up your travels. A friend suggests a stopover in Rome, Italy. But another friend tells you to layover in Helsinki, Finland. You have no idea which choice is best, so you decide to find out by plotting the two cities on a map (see Figure 4-2).
(© John Wiley & Sons Inc.)
FIGURE 4-2: New York City to Singapore: Map # 1.
Accepting the principle that a straight line is the shortest distance between two points, the map seems to make your choice pretty clear, doesn’t it? The itinerary to Singapore via Rome is apparently much shorter than the route via Helsinki. As a result, you call your travel agent and make the appropriate bookings.
Upon hearing your travel plans, your second friend is shocked. “You’re not going by way of Helsinki?” To show your friend the wisdom behind your choice, you take out your map and note the obvious: The linear distance from New York to Singapore is shorter via Rome. Whereupon your friend produces a map of her own (see Figure 4-3).
Looking at the map in Figure 4-3, three things are suddenly obvious.
First, the global view in this map is much different than in Figure 4-2.
Second, the results are different, too. In Figure 4-3, going to Singapore via Helsinki appears much shorter than the route via Rome.
Third, one of these maps is lying, but which one?
(© John Wiley & Sons Inc.)
FIGURE 4-3: New York City to Singapore: Map #2.
APPLIED GEOGRAPHY: PUTTING YOUR BEST PROJECTION FORWARD
Figures 4-2 and 4-3 provide different perspectives on air routes between New York City and Singapore. While this may seem a strictly academic exercise, airlines that compete on long-range international itineraries take the matter very seriously. There’s an old saying: “Time is money.” And for that reason, many business travelers (if they have a choice) prefer the shortest route to get them where they’re going. Airline executives know this. Accordingly, marketing strategies sometimes involve making maps that present the airline’s route system in the best light possible. And doing that, of course, involves choosing the best possible projection.
If you have a globe handy, you can determine the shorter of the two itineraries from New York City to Singapore. Get a string, pull it taut, and place it on the map so that the string connects New York City and Singapore. What you observe is that the string passes over the Arctic Circle and shows that a stopover in Helsinki is a minor detour, but a stopover in Rome is a major detour. If you don’t have a globe, you can’t do this demonstration, can you?
Wading through lies in search of the truth
The maps in both Figure 4-2 and 4-3 are lying. But the map in Figure 4-3 provides the most accurate — that is, most globe-like — perspective regarding the shortest route between New York and Singapore. I’d really love to be able to prove that to you right here on the page of this book, but therein lies the problem — literally. This page is flat. To find out which route is shortest, you need a map that really looks like the world itself. That is, you need a globe.
Because a globe doesn’t come with this book, you have to come to grips with the four ways in which maps can lie: distance, direction, shape, and area.
Distance
Theoretically, transferring a curved Earth to a flat map involves selectively stretching some parts of Earth’s surface more than others. For example, imagine two cities are 1,000 miles apart and the land between them gets stretched a great deal during the map-making process. Now imagine that elsewhere on Earth, two other cities are also 1,000 miles apart, but the land between them gets stretched just a little to make the very same map. On the resulting maps, the distance of 1,000 miles isn’t portrayed the same.
Direction
The situation with direction is pretty much the same as with distance. By stretching a globe
