Have you a little iron horse-shoe magnet? It looks like any-other bent bar of iron, but pins, needles and other bits of metal will cling to the ends of the horse-shoe. They will even jump a little way to get to the magnet, and can be lifted by it. A magnet is much more than an interesting toy. Magnetism is one of the biggest forces in nature. It is mixed up with electricity and stormy weather and all sorts of things. Our big, beautiful earth is a huge magnet. Its greatest points of attraction are at opposite ends, just as they are in the little horse-shoe magnet. One end of the earth magnet is away up near the north pole ; the other is just as far down, near the south pole. These places are called the earth's magnetic poles. Their attraction for iron is made use of in navigating ships on the ocean.

The little instrument that, by the attraction of the magnetic poles for iron, is used to find directions at sea, is called the compass. It is a round box with a glass cover, and with a dial marked off something like the face of a clock. Over the dial a double-pointed needle— like the hands of a watch—swings on a pivot around the center. But the dial of a compass is not marked off in figures like the face of a watch. It is lettered. "N" means north, "S" south, "E" east and "W" west. These letters divide the dial into four quarters. Between them are "NE," northeast, and so on, up to a great many subdivisions. The captain of a vessel holds the compass-box level. The needle swings around and points toward the north magnetic pole. He turns the box slowly until the needle end rests over the "N," north on the dial. Comparing that with the way in which the vessel is moving forward, he can tell in which direction he is journeying, and can direct the pilot to steer in any direction in which he wishes to go.