I have a question regarding the answer given 4-24-1987 to the question above. Why would Cecil answer such a question without reference to what is surely the most important factor? Before the invention of the magnetic compass, determining your bearing when in a non-descript (i.e. the middle of the ocean) or unfamiliar location required orienting yourself to a stellar body, which, in the northern hemisphere is Polaris. If you were facing that way anyway, it makes the most sense to orient your map in the same manner (unless religious sensibilities override practicality in the case of those maps with east on top).
Southern denizens of course were in no position to object when the convention was established.
Yea, but it’s an *Australian *map… and those guys are just weird; it’s probably a result of all the blood rushing to their heads for being upside down all their lives. The whole place is odd, I mean just look at the platypus… you don’t get weirdness like that up here.
Dude, Finland… we don’t get weird animals here. They’re found in the *southern *parts of the world. Places like Anchorage and Reykjavik are south of me.
Having worked with maps and having been a cartophile for decades, I once had a discussion with a land surveyor/development site plat preparer about this convention when his plats, which I was reviewing for my work, did not have north upwards. He insisted that that was a ridiculous concept and not a standard. He preferred to draw his site plat maps with the viewer looking (up) into the entrance to the development site.
…So your country’s going to deny having anything to do with supplying Santa Claus (also known as Saint Nicholas, Sinterklaas, Father Christmas - fellow’s got a lot of aliases, suspicious all by itself) with magical reindeer, huh?
What gets me is the way some maps have the equator about 3/5ths of the way down the page, so everything in the southern hemisphere looks tiny. (No, Greenland is not twice the size of Australia).
It’s not the placement of the equator that makes Greenland look so big. It’s the use of the Mercator projection, which distorts areas in order to preserve orientation to the compass. In other words, up on a Mercator map is always due north, which is very helpful for navigation by compass, the projection’s intended purpose.
This is a consequence of the stretching and squeezing required to represent the curved surface of the earth on a flat map. You can preserve some attributes: proportional area, direction, distance along a line, but not all of them at the same time.
Some people interpret the Mercator map’s distortion of area as European imperialism, and have promoted the use of the world map developed by Dr. Arno Peters as a remedy. The Mollweide projection also produces truly proportional areas, but is bounded by an oval, rather than the rectangular form of the Mercator and Arno maps.
That’s not all there is to the Mercator projection: The same can be said of the Peters projection, after all. What’s unique about the Mercator projection is that it preserves all compass bearings: So, for instance, not only is a vertical line due north, but a a bearing of (say) 17.362 degrees from North will also be 17.362 degrees from vertical on the map.
That said, while this is a useful property for some applications (Google Maps, for instance, and some problems in navigation), it’s completely pointless for others, and there’s no reason why a map on the wall of a classroom should be a Mercator projection. Personally, I’ve always preferred the projections that slice up the globe in the middle of the oceans, like a peeled orange: They come close to preserving both shape and area, at the expense only of severely distorting the oceans, which aren’t as important for most classroom purposes.
The Mercator Projection is the way it is because it makes lines that keep going in one direction (northeast, for example) go in straight lines. Other map projections can’t do that, although they fix other problems. If you think that having those lines straight (they’re called “rhumb lines”) is useful, then you want a Mercator Projection. Making Greenland look bigger than Australia is just a side effect of the math.
Putting the equator nearer the bottom is not necessary, but, because the Mercator projection can’t go all the way to the poles (they’re infinitely far away), which means that you have to pick a northern and a southern latitude to cut it off, and because Spitzbergen is further north than the Cape of Good Hope is south and most people aren’t really interested in the details of Antarctica, you can cut off more of the Southern Hemisphere with no important loss.
Cecil leaves out an interesting detail in that column.
He mentions that for a while in the middle ages, it was common to put East at the top of maps. But he doesn’t mention the reason for that.
It was during the Middle Ages, with the Catholic Church dominating much of Europe. And Church scholars had decided, based on Bible stories, that the Garden of Eden was in the East, and at the top of the world (Adam & Eve went down from the Garden). Therefore, it was up, and thus East should be at the top of any decent, Christian map.
Well, I suppose that carrying your straight line past the “top” or “bottom” edge of a full-globe Mercator (i.e., passing over the North or South Pole) would change your compass heading. After all, you can’t go any further north than the North Pole. One more step and you’re headed south.
That said, if your bearing is true east or west, you can do that forever on a Mercator.
[QUOTE=John W. Kennedy;12840919
Putting the equator nearer the bottom is not necessary, but, because the Mercator projection can’t go all the way to the poles (they’re infinitely far away), which means that you have to pick a northern and a southern latitude to cut it off, and because Spitzbergen is further north than the Cape of Good Hope is south and most people aren’t really interested in the details of Antarctica, you can cut off more of the Southern Hemisphere with no important loss.[/QUOTE]
No, the Mercator projection CAN go all the way to the poles, it’s just that the poles are represented by a line rather than a point.
