ACTIVITY 348: Read the newspaper article written by Wendy Grossman which is about a seemingly supernatural ability: walking on fire. Five paragraphs have been removed from the article. Choose from the paragraphs (A-to-F) the one which fits each gap 1-to-5. There is one extra paragraph which you do not need to use. Then check the correct answers.

Firewalkers were warned to walk briskly and avoid letting their toes sink into the embers. Wet blankets and buckets of water were positioned at the end of the walk, so they could cool their feet down quickly afterwards.

It takes an average four or five steps to cross a 3.5 metre bed of coals. At the recommended brisk pace, each foot is in contact with the embers for no more than a second or a second and a half, not long enough to cause burns.

In 1984 tens of thousands of Californians paid hundreds of dollars each for "fear seminars", at which firewalks were promoted as the cure for everything from drug addiction to insomnia.

Earlier this month, 120 sceptics gathered in Southampton to prove that anyone can walk over red-hot coals and come away with their feet intact. The "firewalk" was organised by Wessex Skeptics, one of a network of sceptics' groups around the country.

Firewalking is such a spectacular defiance of common sense that throughout history it has been used as evidence of spiritual superiority. There are references to it in the Bible, and it has been reported in such different places as South Africa, Japan and Bali.

In fact, firewalking has little to do with mind over matter and everything to do with the laws of physics concerning heat capacity and conductivity. To set up this month's event, the Wessex Skeptics raked the embers of a bonfire of storm-damaged oak and beech into a bed about 1 metre wide by 3.5 metres long.

Physicist Robin Allen, a research fellow at Southampton University and president of the Wessex Skeptics, gave a prior talk on the physics involved.

Metal holds large amounts of heat energy and transfers it quickly, whereas air and cake have low heat capacity and poor thermal conductivity. For firewalking, wood and its ash behave like the cake. In some parts of the world, porous rocks are used instead of embers — they are also poor conductors of heat. And, because feet have a high heat capacity, the embers actually cool down when walkers step on them. The trick is not to spend too long on the embers — the effects are cumulative.

At the Wessex Skeptics firewalk, a few blisters did appear, but they were caused by embers sticking to walkers' feet. Experienced firewalkers recommend drying the feet carefully first to avoid this. "The only mind over matter," says Mr Allen, "is finding the courage to take the first step." But don't try it at home. Fire is still fire — and still dangerous.

Wendy Grossman