Why was the source of the Nile a mystery for so long?

When you make a list of the great rivers on the planet, right at the top, surpassing even the mighty Passaic, is the Nile. It's long, it's historic, and it flows due north, which, as anyone can see from looking at a globe, is directly uphill.

A simpleton might argue that the Amazon somehow is more impressive, because of the vastness of its watershed and the biological diversity therein (simpletons use words like "therein" whenever possible). But the Nile is the artery of the planet's most ancient civilization. No Nile, no pyramids. The ancient Egyptians were the first to wonder where the Nile came from; it seemed to gush from nowhere, from the depths of a vast, parched desert. You could go upriver a thousand miles and see not a single tributary, feel not a drop of rain.

During August, the dry season for the Egyptians, the Nile flooded.

Long after most of the planet had been explored, the source of the Nile remained a mystery. The quest for the source reached frenzied proportions in the mid-1800s, when the British Royal Geographic Society funded numerous highly publicized expeditions into the African interior. You have to wonder: Why wasn't the source found earlier? Why didn't someone just tromp upstream until they found the spring from which it spurted? Could that be so difficult?

Yes indeedy. For one thing, if you go up the White Nile (the longer, western branch) far enough, it practically disappears in a swamp. The swamp, in southern Sudan, is called the Sudd, and it's thoroughly nasty. In the wet season it's the size of England.

"It is not surprising that the ancients gave up the exploration of the Nile when they came to the countless windings and difficulties of the marshes; the river is like an entangled skein of thread," wrote Samuel White Baker, a British explorer, in "The Albert Nyanza, Great Basin of the Nile," published in 1866.

(By the way we just noticed a lovely chapter subheading in "How I Found Livingstone" by Henry Morton Stanley: "I Sink to my Neck in the Ooze of the Rungwa.")

South of the Sudd, the Nile channel coheres again. But explorers faced other intimidating obstacles. Slave traders had brought terror to the interior. Western explorers who managed to overcome the cataracts, brutal heat and malaria still had to deal with cutthroat slave traders and ivory hunters as well as powerful and not necessarily friendly tribal chieftains.

For example, guarding the headwaters of the Nile at Lake Victoria was Mutesa, King of Buganda, a nation of 3 million people. Mutesa was a formidable person.

"In the manner of Queen Victoria he did not look round when he chose to sit down; a chair was automatically placed in readiness for him, except that in his case it was a page crouching on his hands and knees," wrote Alan Moorehead in "The White Nile."

(Western accounts of African explorations are no doubt full of exaggerations, not to mention racist attitudes, so it's hard to know which exoticisms are real and which are imagined or invented. Certainly Moorehead's description of Rumanika, King of Karagwe, has a rather riveting Felliniesque quality: "He kept an extraordinary harem of wives who were so fat they could not stand upright, and instead groveled like seals about the floors of their huts.")

The final problem with the Nile is that it has no single source. The most prominent source is Lake Victoria. Though known to the Arabs in the slave trade, the first European to see it was British explorer John Hanning Speke, on Aug. 3, 1858. Four years later, on July 28, 1862, during a different expedition, Speke found the falls on the northern edge of the lake where the White Nile pours forth.

Though Speke was convinced he had found the source, there were skeptics back at the Royal Geographic Society, including Speke's rival in African exploration, Richard Francis Burton. They were supposed to debate the issue in front of society members, but the day before the debate Speke, engaged in a pleasant afternoon of sport shooting, accidentally blew himself away while climbing over a fence.

The lesson: Perilous cartographic adventures don't kill people, guns kill people.

The Mailbag:

A couple of months ago we began a column by stating that a raisin is a very young prune. "You poor, dear, misinformed man!" responds Lorelle Pederson of Newport, Wash., just one of the many readers shocked by our statement. She writes that grapes "grow on a vine and have seeds. There are light-colored grapes and dark grapes. When grapes are dried they become raisins."

Dear Lorelle: If we were to say that Pi is roughly 3.14157, and you happen to know that Pi is closer to 3.14159, you can assume we made an error. But if we say in print that we've been fiddling with a tape measure and a draftsman's compass and have made the astonishing discovery that Pi is exactly 3, right on the nose, you can assume we are engaging, however pitifully, in the communicative gambit known as "humor."

So it is with the raisin/prune line. We were joshing. Why did we think it was funny to write that? Hard to say. Humor, as we've noted in the past, generally follows the pattern of overlapping but incompatible frames of reference. Perhaps in this case the jocosity-inducing incompatibility lies between the referential frames "responsible journalism" and "preposterous lie."

Not that we don't err. Recently we said the military uses the term "0 hours" to refer to midnight. Our readers, some brandishing M-16s, have pointed out that the military calls midnight "2400 hours." (We've been fuzzy with numbers ever since we took that frag at Khe Sanh.)