How do airports cope with millions of passengers?

An American couple once arrived at London’s Heathrow Airport unable to recall the name of the family they were staying with near the airport or the name of the street. All they had was a street number and `Oh, yeah, the street’s named after a tree, and it’s close to some store called Sainsbury’. To […]

How they make razor blades sharp

Every 24 hours, as many as 25,000 hairs grow up to half a millimetre on the face of the average adult male. The modern razor blade, honed to perfection, can cut its way through this stubble forest to give a close, smooth and safe shave. Men began removing their fast-growing facial hair thousands of years […]

How PTFE is made

PTFE is made from chlorodifluoromethane, a widely used refrigerant liquid known as Freon 22. The American engineer Dr Roy Plunkett discovered that heating Freon 22 produces the gas tetrafluoroethene. Under a pressure of about 45-50 atmospheres and in the presence of a peroxide catalyst, this gas undergoes a chemical change, and the result is PTFE […]

How the US Navy launched the zip fastener

The US Navy pioneered the use of zip fasteners in 1918 when it ordered 10,000 of them to do up ‘wind-cheating’ flying suits. The first slide fastener – the ancestor of the zip – had been devised by an American engineer, Whitcomb Judson, in 1893. He designed a ‘clasp locker’ as a quick method of […]

Electronic slot machines

The latest generation of slot machines check coins electronically. As soon as a coin is inserted, its conductance – its ability to pass electric current – is tested. Broadly acceptable coins then pass through a gate and are allowed to run down a ramp and between two magnets. Once again, the speed at which they […]