Meridian Hill and Political Geography
“‘What’s the good of Mercator’s North Poles and Equators, Tropics, Zones, and Meridian Lines?’
So the Bellman would cry: and the crew would reply ‘They are merely conventional signs!’”
— Lewis Carroll – The Hunting of the Snark
The Earth spins on an axis.
This means that the equator, halfway between the poles, divides the earth into northern and southern hemispheres. The equator can be nowhere else. Its placement is determined by the physical world and lines of latitude are given values according to their distance from this “prime parallel,” so named because all lines of latitude are parallel to each other:
Follow the parallels away from the equator: From a circumference of over 24,900 miles and a location of zero degrees latitude they gradually get smaller and smaller still, finishing at the poles with the location of 90 degrees latitude and a dimension of precisely zero.
To know where you are on Earth, however, you need to know more than just how far you are away from the prime parallel. The counterpart to a line of latitude is a line of longitude, and these lines are quite different creatures:
Note that all these lines of longitude have roughly the same circumference, each and every one of them circling from pole to pole. Each one traces a line straight up and down the face of the globe, cutting through the equator on its way to the other pole, 180 degrees (and about 12,450 miles) away.
So which one is the zero-degree meridian—the prime meridian? It depends.
In fact, the determination of a prime meridian is completely arbitrary…and ultimately a hotly political topic with a long history.
The Ancient Greek geographer Ptolemy was the first to use a prime meridian consistently, and he chose a line past the western tip of Africa so as not to have to use negative numbers.
“My numbers only go up.” – Ptolemy
In the fifteenth and sixteenth centuries, cartographers variously placed their prime meridians around spots in the Atlantic, among them Cape Verde, the Azores, and the Canary Islands. With Meridians, any country could have one—and by 1900 there was no shortage of contenders for the One Line to Rule Them All:
- Tenerife
- Lisbon
- Madrid
- Philadelphia
- Rio de Janeiro
- Paris
- Brussels
- Bern
- Pisa
- Oslo
- Florence
- Rome
- Naples
- Stockholm
- Warsaw
- St. Petersburg
- Jerusalem
- The Great Pyramid of Giza
Even Washington, D.C. got in the game.
…and America said we would have FOUR meridians in the capital: The Capitol Building, The Old Naval Observatory, the New Naval Observatory, and the White House.
Of the four, the one that stuck most was the White House Meridian, along 16th Street Northwest:
About two miles north of the White House, right along 16th Street NW, is a beautiful hill ripe for a park. President Thomas Jefferson placed a marker there indicating the White House Meridian, thus the subsequent name Meridian Hill Park.
Italian-Renaissance-style terracing added in the early twentieth century gives the park a unique character in Washington, befitting its interesting history as a marker of a distinctly American Prime Meridian. It’s worth a visit!
