The Second Book of General Ignorance

Who made the first flight in an airplane?

We don't know his name, but he beat the Wright Brothers to it by fifty years.

He worked for Sir George Cayley (1773-1857), an aristocratic Yorkshireman and pioneer of aeronautics, who carried out the first truly scientific study of how birds fly. Cayley correctly described the principles of "lift, drag, and thrust" that govern flight and this led him to build a series of prototype flying machines. His early attempts with flapping wings (powered by steam and gunpowder engines) failed, so he turned his attention to gliders instead.

In 1804 he demonstrated the world's first model glider and, five years later, tested a full-size version--but without a pilot. More than three decades passed before he finally felt ready to trust his "governable parachute" with a human passenger. In 1853, at Brompton Dale near Scarborough, the intrepid baronet persuaded his reluctant coachman to steer the contraption across the valley. It was this anonymous employee who became the first human ever to fly in a heavier-than-air machine.

The coachman, so the story goes, was not impressed. He handed in his notice as soon as he landed, saying, "I was hired to drive, not to fly." A modern replica of Cayley's glider, now on show at the Yorkshire Air Museum, successfully repeated the flight across Brompton Dale in 1974.

But wings weren't Sir George's only legacy. With his work on the glider's landing gear, he literally reinvented the wheel. Needing something light but strong to absorb the aircraft's impact on landing, he came up with the idea of using wheels whose spokes were held at tension, rather than being carved from solid wood. These went on to transform the development of the bicycle and the car and are still widely used today.

And that wasn't all. Cayley was a remarkably prolific inventor, developing self-righting lifeboats, caterpillar tracks for bulldozers, automatic signals for railway crossings, and seat belts. Even more remarkably, he offered all these inventions for the public good, without expecting any financial reward.

The Wright Brothers made their famous flights half a century later, in 1903. They were inspired by Cayley and by another unsung hero of aviation, Otto Lilienthal (1848-96), a Prussian known as the "Glider King." He was the first person to fly consistently: in the decade before the Wright Brothers, he made more than 2,000 glider flights before falling to his death in 1896. His last words were humble and poignant: "Small sacrifices must be made."



How many legs does an octopus have?

Two.

Octopuses have eight limbs protruding from their bodies, but recent research into how they use them has redefined what they should be called. Octopuses (from the Greek for "eight feet") are cephalopods (Greek for "head foot"). They use their back two tentacles to propel themselves along the seabed, leaving the remaining six to be used for feeding. As a result, marine biologists now tend to refer to them as animals with two legs and six arms.

An octopus's tentacles are miraculous organs. They can stiffen to create a temporary elbow joint or fold up to disguise their owner as a coconut rolling along the sea floor. They also contain two-thirds of the octopus's brain--about 50 million neurons--the remaining third of which is shaped like a doughnut and located inside its head, or mantle.

Because so much of an octopus's nervous system is in its extremities, each limb has a high degree of independence. A severed tentacle can continue to crawl around and, in some species, will live for several months. An octopus's arm (or leg) quite genuinely has a mind of its own.

Each arm on an octopus has two rows of suckers, equipped with taste buds for identifying food. An octopus tastes everything that it touches. Male octopuses also have a specialized arm in which they keep their sperm. It's called the hectocotylus and is used for mating. To transfer the sperm, the male puts his arm into a hole in the female's head. During copulation the hectocotylus usually breaks off, but the male grows a new one the following year.

The way octopuses mate was first described by Aristotle (384-322 bc), but for more than 2,000 years no one believed him. The French zoologist Georges Cuvier (1769-1832) rediscovered the process in the nineteenth century and gave the hectocotylus its name. It means "a hundred tiny cups" in Greek.

Genetic variations sometimes cause octopuses to grow more than eight limbs. In 1998 the Shima Marineland Aquarium in Japan had a common octopus on display that had 96 tentacles. It was captured in nearby Matoya Bay in December 1998 but died five months later. The multi-armed cephalopod managed to lay a batch of eggs before its death. All the offspring hatched with the normal number of arms and legs, but none survived longer than a month.

Octopuses occasionally eat their own arms. This used to be blamed on stress but is now thought to be caused by a virus that attacks their nervous system.



What color are oranges?

That depends.

In many countries, oranges are green--even when ripe--and are sold that way in the shops. The same goes for lemons, mangoes, tangerines, and grapefruit.

Oranges are unknown in the wild. They are a cross between tangerines and the pomelo or "Chinese grapefruit" (which is pale green or yellow), and were first grown in Southeast Asia. They were green there then, and today they still are. Vietnamese oranges and Thai tangerines are bright green on the outside and orange only on the inside.

Oranges are subtropical fruit, not tropical ones. The color of an orange depends on where it grows. In more temperate climes, its green skin turns orange when the weather cools, but in countries where it's always hot the chlorophyll is not destroyed and the fruits stay green. Oranges in Honduras, for example, are eaten green at home but artificially "oranged" for export.

To achieve this, they are blasted with ethylene gas, a by-product of the oil industry, whose main use is in the manufacture of plastic. Ethylene is the most widely produced organic compound in the world: 100 million tons of it are made every year. It removes the natural outer green layer of an orange, allowing the more familiar color to show through.

Far and away the world's largest producer of oranges is Brazil (18 million tons a year), followed by the United States, which grows fewer than half as many. American oranges come from California, Texas, and Florida. They were often synthetically dyed until the Food and Drug Administration banned the practice in 1955.

You can't tell the ripeness of an orange by its color, no matter where it's from. If an orange goes unpicked, it can stay on the tree till the next season, during which time fluctuations in temperature can make it turn from green to orange and back to green again without the quality or flavor being affected.

The oranges you see on display in your supermarket certainly appear to be completely orange, but you may now start to worry they've been gassed. Don't.

Ethylene is odorless, tasteless, and harmless, and many fruits and vegetables give it off naturally after they're picked. Ethylene producers include apples, melons, tomatoes, avocados, and bananas. The gas isn't bad for you, but it can affect other kinds of fruit and vegetables--which is why you should keep apples and bananas separate from, say, lemons or carrots (and, of course, oranges).

Ethylene has other uses apart from making plastics (and detergents and antifreeze) and altering the color of an orange. If you want to speed up the ripening process of an unripe mango, keep it in a bag with a banana.



What's the name of the most southerly point of Africa?

It's not the Cape of Good Hope.

The residents of nearby Cape Town often have to explain this to visitors. The southernmost point of the continent is the altogether less famous Cape Agulhas, 93 miles (150 kilometers) southeast of the Cape of Good Hope.

The usual reason given for the Cape of Good Hope's fame (and its name) is that it was the psychologically important point where sailors, on the long haul down the west coast of Africa on their way to the Far East, at last began to sail in an easterly, rather than a southerly, direction.

On the other hand, it might have been an early example of marketing spin.

Bartolomeu Dias (1451-1500), the Portuguese navigator who discovered the Cape of Good Hope and became the first European to make the hair-raising trip around the foot of Africa, named it Cabo das Tormentas ("Cape of Storms"). His employer, King John II of Portugal (1455-95), keen to encourage others to adopt the new trade route, overruled him and tactfully rechristened it Cabo da Boa Esperança ("Cape of Good Hope").

The king died childless, at the age of forty. Five years later Bartolomeu Dias also died. He was wrecked in a terrible storm--along with four ships and the loss of all hands--off the very cape he had so presciently named.

Cape Agulhas is equally treacherous. It is Portuguese for "Cape of Needles," after the sharp rocks and reefs that infest its roaring waters. The local town is home to a shipwreck museum that commemorates "a graveyard of ships."

Because of its isolation and rocky, inaccessible beach, the area is rich in wildlife. On land, it is home to the critically endangered micro-frog (Microbatrachella capensis) and the Agulhas clapper (Mirafra [apiata] majoriae), a lark whose mating display involves much noisy wing-flapping.

In the waters offshore, between May and August, the sea boils with billions of migrating South African pilchards (Sardinops sagax). These shoals form one of the largest congregations of wildlife on the planet, equivalent to the great wildebeest migrations on land, and can stretch to be 3.7 miles (6 kilometers) long and 1.2 miles (2 kilometers) wide. Hundreds of thousands of sharks, dolphins, seals, and seabirds travel in the fishes' wake, snacking on them at will but making little impact on the overall numbers.

Cape Agulhas is at 34° 49' 58'' south and 20° 00' 12'' east and it is the official dividing point between the Atlantic and Indian oceans. If you sailed past it, along the relatively unimpressive, gradually curving coastline, you probably wouldn't even notice it but for the cairn that marks the tip's exact location.



What's the hardest known substance?

It's not diamonds anymore.

In 2005 scientists at Bayreuth University in Germany created a new material by compressing pure carbon under extreme heat. It's called hyperdiamond or aggregated diamond nanorods (ADNR), and although it's incredibly hard, it looks rather like asphalt or a glittery black pudding.

It's long been known that one form of pure carbon (graphite) can be turned into another (diamond) by heat and pressure. But the Bayreuth team used neither. They used a third form of pure carbon, fullerite, also known as buckminsterfullerene or "buckyballs." Its sixty carbon atoms form a molecule shaped like a soccer ball, or like one of the geodesic domes invented by American architect Richard Buckminster Fuller (1895-1983).

The carbon atoms in diamond are arranged in cubes stacked in pyramids; the new substance is made of tiny, interlocking rods. These are called "nanorods" because they are so small--nanos is Greek for "dwarf." Each is 1 micron (just over one millionth of a yard) long and 20 nanometers (just over 20 billionths of a yard) wide--about 1/50,000th of the width of a human hair.

Subjecting fullerite to extremes of heat (4028°F) and compression (200,000 times normal atmospheric pressure) created not only the hardest but also the stiffest and densest substance known to science.

Density is how tightly packed a material's molecules are and is measured using X-rays. ADNR is 0.3 percent denser than diamond.

Stiffness is a measure of compressibility: the amount of force that must be applied equally on all sides to make the material shrink in volume. Its basic unit is the pascal, after Blaise Pascal (1623-62), the French mathematician who helped develop the barometer, which measures air pressure. ADNR's stiffness rating is 491 gigapascals (GPa): diamond's is 442 GPa and iron's is 180 GPa. This means that ADNR is almost three times harder to compress than iron.

Hardness is simpler to determine: if one material can make a scratch mark on another, it's harder. The German mineralogist Friedrich Mohs (1773-1839) devised the Mohs hardness scale in 1812. It starts at the softest end with talc (MH1). Lead is fairly soft at MH1½; fingernails are graded MH2½ (as hard as gold); in the middle are glass and knife blades at MH5½. Ordinary sandpaper (which is made of corundum) is MH9, and right at the top end is diamond at MH10. Since ADNR can scratch diamond, it is literally off the scale.

And there's more disappointing news for diamond fans: they aren't "forever." Graphite (which, oddly enough, is one of the softest known substances, as soft as talc) is much more chemically stable than diamond. In fact, all diamonds are very slowly turning into graphite. But the process is imperceptible. There's no danger of anybody suddenly finding his or her earrings have become pencils.



What's the strangest substance known to science?

H2O.

Water, or hydrogen oxide, is the strangest substance known to science. With the possible exception of air, it's also the most familiar. It covers 70 percent of the earth and accounts for 70 percent of our own brains.

Water is oxygen linked to hydrogen (the simplest and most common element in the universe) in the simplest way possible. Any other gas combined with hydrogen just produces another gas: only oxygen and hydrogen make a liquid.

And it's a liquid that behaves so differently from any other that theoretically it shouldn't exist. There are sixty-six known ways in which water is abnormal, the most peculiar being that nothing else in nature is found simultaneously as liquid, solid, and gas. A sea full of icebergs under a cloudy sky may appear natural, but in chemical terms it is anything but. Most substances shrink as they cool, but when water falls below 39.2°F, it starts to expand and become lighter. That's why ice floats and why wine bottles burst if left in the freezer.

Each water molecule can attach itself to four other water molecules. Because water is so strongly bonded, a lot of energy is needed to change it from one state to another. It takes ten times more energy to heat water than iron.

Because water can absorb a lot of heat without getting hot, it helps keep the planet's climate steady. Temperatures in the oceans are three times more stable than on land and water's transparency allows light to penetrate its depths, enabling life in the sea. Without water there would be no life at all. And though you can put your hand right through it, it's remarkably difficult to compress, and water hit at speed is as hard as concrete.