Susan Hyatt, age 12, of West Asheville,
Does a magnet, point north?
Mankind found natural magnets before the dawn of history ‑ and he has been puzzled about them ever since. Bits of information have been gathered through the ages, but we are still not sure of all the reasons why a magnet behaves as it does. This has not stopped us from making use of its magic qualities. Long ago, man learned to use a magnet as compass. Later, we learned how to use it to make electric power.
A natural magnet is a dark lump of iron ore called magnetite. It gives Itself away by sticking to bits of iron and steel: The first solid study of these magic qualities was done by Dr. William Gilbert of Elizabethan days. Gilbert studied a magnet hanging from a string and figured out why one end swings around to point north, the other to point south. He saw that the two ends of his magnet are drawn by powerful forces near the earth's poles.
The solid earth, Gilbert reasoned, must itself be a giant magnet. And he was quite correct. Since the poles of a little magnet are related to the big earthfs magnetic poles, he named them poles also. It seemed natural to name the end which points north the north pole of the magnet and the opposite end the south pole. This, however, is confusing as you can discover by testing a pair of bar magnets for yourself.
Place the two bars end to end. Two north poles will spring apart or repel each other, as will two south poles. The law of magnets says, that like poles repel and opposites att7ract each other. The end of a compass magnet which points to the north is actually its opposite, or south pole. It is much simpler, of course, to call the north‑pointing end of a compass magnet its north pole. If you wish to be very precise, you may call this the north‑seeking pole and the opposite end the south‑seeking pole.
If a pilot depended entirely upon his magnetic compass, a trip to Greenland might land him in Iceland. This is because the earth's magnetic poles are more than a thousand miles from its geographic poles. The magnetic poles which draw the compass needle are the two ends of the giant magnet which is the earth. The geographic poles are the two ends of the axis around which the Big Ball rotates. They are the basis of the system of longitude and latitude. The compass, then does not point directly to the north pole. What's more, the earths magnetic poles tend to shift. A pilot must study charts to make allowances for these variations.
The Chinese, it is thought, were the first to discover that a sliver of magnet can be used as a compass. Sometimes the magnet was hung on a string and sometimes placed on a piece of cork floating in a bowl of water. In either case, when left to swing freely, one end of the needle will point out the north and from this the traveler can figure out his directions.