"Here's a simple experiment that you might want to try if there is absolutely nothing else going on in your life. All you need is a cork, a bar magnet, and a pail of water. Simply attach your magnet to your cork, then drop it into the water, and voilà (literally, "you have a compass")-you have a compass. How does it work? Simple. Notice that, no matter which way you turn the bucket, the cork always floats on top of the water (unless the magnet is too heavy). Using this scientific principle, early hardy mariners were able to tell at a glance whether they were sinking!"