The mysteries of 'pyramid power'
For some people, the great pyramids of Egypt are a weird mystery. People still discuss how they might have been built, and why. But the Great Pyramid of Giza - built almost 4,000 years ago - for the fourth dynasty king Khufu, or Cheops, gets particular attention.
Some people argue Khufu's Pyramid preserves dead animals and sharpens metal blades. They think there is a kind of mysterious energy in the shape of the pyramid and say that if replicas are built to scale and the pyramid is aligned on a north-south axis, strange things happen.
In the 1920s, a Frenchman, Antoine Bovis, who was visiting the pyramid, claimed he noticed that animals that died in the King's Chamber became mummified rather than decomposing. He tried this at home in Nice with a replica of the pyramid, and claimed it worked. Critics say there is no actual science behind his theories.
Czech engineer Karel Drbal heard of Bovis' experiment and tried it out for himself, using a razor blade. He used a razor that normally gave five shaves, and claimed he could use it at least 50 times. Test his theory by making your own pyramid.
Here's how to do it. Cut four equilateral triangles from cardboard. They can be as big or small as you like. Tape the sides together to make the pyramid shape. Make a block roughly one-third the height of the pyramid that can easily fit inside it without lifting any of the sides. Position the pyramid so that the baselines point at magnetic north and south - you might need to use a compass.
Then grab some old razors and put them on the block, making sure they are positioned east and west. Cover with the pyramid. Leave them there overnight. If you don't want to use razors, try using flowers.
For the maths behind the pyramid: http://www.gizapyramid.com/stevebedford.htm