QI's best science and tech facts: from the first selfie to power stations and tyres

Which kind of power station produces the most radiation?

Coal-fired ones: they emit 100 times more radiation than nuclear plants. Coal contains traces of radioactive uranium and thorium. In small amounts, these present no danger, but burning large quantities of coal for electricity produces “fly ash” (ash that flies up into the air), in which the radioactive elements are concentrated at up to 10 times their original levels. This also contaminates the soil around a conventional power plant. Nuclear waste, by contrast, is contained and safely disposed of.

As a result, people who live near a coal-fired power station may consume crops and livestock with twice as much radiation as those who live near a nuclear plant. But neither represents a serious threat to health.

The chance of getting ill from a coal-fired plant is about one in 100 million; with a nuclear plant this drops to one in a billion. You are four times more likely to be struck by lightning than to be affected by radioactivity from any power station.

The nuclear plant at Sellafield stores radioactive seagulls. It was feared that birds landing on the site might pick up radiation and then fly away, spreading it across the surrounding countryside. The management solved the problem by employing snipers to kill any gulls that did this. The hundreds of dead birds are designated low-level nuclear waste and stored in a freezer.

Why is gasoline called gasoline?

It’s got nothing to do with gas. Gasoline (American English for petrol) gets its name from John Cassell (1817–65), a Mancunian publisher, coffee merchant and temperance campaigner who began importing and distributing crude oil into Britain and Ireland from Pennsylvania in the 1860s. He called his product “Cazeline”, after himself, and sold it for indoor lamps.

It proved a great success, so much so that by 1865 he was taking Samuel Boyd, a Dublin shopkeeper, to court for selling counterfeit Cazeline. Boyd had changed the “c” to a “g” on all his stock records and then claimed he’d coined the word “gazeline” himself from gasogène, an early French device for making carbonated water. The judge was not impressed and Cassell won the case. But Boyd had the last laugh. Probably because of its similarity to the word “gas”, “gasoline” caught on and became the preferred name for the product. The last recorded use of the word Cazeline was in 1920.

Which company is the world’s largest manufacturer of tyres?

Not Pirelli. Or Michelin. Or Dunlop. The world’s largest tyre manufacturer is Lego. It makes up to 320 million tyres a year for its toys, far outstripping Michelin’s 170 million. Lego tyres are smaller and not full of air, but they’re definitely rubber and they go on the wheels of vehicles. There are more than 60 Lego bricks for every person in the world. More than 400 billion have been produced since 1949. Remarkably, all Lego bricks are fully compatible, whether they were made at the beginning or yesterday.

What was the first chainsaw used for?

Delivering babies. In 1783, a Scottish doctor called John Aitken created the first chainsaw – for use by midwives. It was hand-powered and had a fine serrated chain with a handle at either end.

By 1830, this had evolved into the osteotome (from the Greek for “bone-cutter”), which was also hand-held and had a continuous loop of chain powered by a handle rather like an old-fashioned egg whisk. It is clearly recognisable as the forebear of the modern chainsaw.

Aitken developed his chainsaw to perform a very tricky operation known as a symphysiotomy. The pubic symphysis is the cartilage that joins the left and right pubic bones (symphysis means “growing together”).

Cutting this joint was an extreme measure used to widen the pelvis in the event of a difficult birth. It often ended up damaging the bladder and urethra and could make walking difficult and painful. It was replaced by the Caesarean section but is still used in remote areas, or where the risk of a Caesarean section is too high.

Chainsaws were eventually adapted for use on trees. They were a welcome invention for lumberjacks as they replaced a tool called the “misery whip” – a saw 10 feet long with a handle at either end that had to be operated by two men. Before 1945, most forestry chainsaws were also two-man devices, as they were too cumbersome and heavy for one man to hold.

When was the selfie invented?

1839. Robert Cornelius, an American chemist, silversmith and lamp manufacturer, took the first photographic self-portrait. He is glaring past the camera with tousled hair and his arms folded. Due to long exposure times, he would have had to stay in position for a full minute.

Photographic selfies were common in the early days –photographers often acted as their own models. If you count drawings and sculptures, the oldest selfie is much older. Artists have been putting themselves into pictures for millennia.

There is a stone selfie in ancient Egypt, carved by a sculptor called Bak in 1365BC. According to the Ancient Greek writer Plutarch, the sculptor Phidias put his own face on to the shield of his bronze statue of the goddess Athena in the Parthenon – an outrage that got him sent to prison.

The first known photograph was taken in 1826. It was a rather dull view from outside the workshop of the French inventor Joseph Nicéphore Niépce (1765-1833). The exposure period took so many hours that, in the final photograph, the sun appears to be shining on two sides of a courtyard at once. Later on, Victorian exposure times were cut down to 30 seconds. Because this is too long to hold a convincing smile, it has given us the unfair impression that the Victorians were humourless.

In photographs of babies, Victorian mothers were sometimes behind them, covered in cloth so they could not be seen holding the child still while its picture was taken. At the other end of things, many Victorians had photos taken of their relatives after death – until the 1880s, photographers’ adverts often said they were ready “to make pictures from corpses if desired”. ?

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