Compasses have been helping us find our way for centuries

By Al Lowe
Contributor

Everyone nowadays knows about magnets and compasses. If you go into a strange lake, or a new part of the woods without a compass, you are indeed a fool. We take this navigation aid for granted. We also know that the earth itself is a great big magnet.
When and where did all this begin? We know only a little more now than we did thousands of years ago. This is truly one of the world’s great mysteries, with a lot of unanswered questions.
Plato, in ancient Greece, commented on the wonder of some iron ore which could hold up iron rings. He was talking about a type of iron ore which we call the ‘lodestone.’ In those days, the lodestone was supposed to have magical properties.
Sometime in the first century A. D., the use of the lodestone as a compass for ships came about. This was a crude compass indeed. The lodestone was placed on a piece of wood, the wood floated in a bucket of water, and the bucket kept on the deck of the ship. This was modernized, in a couple of hundred years, to make use of a narrow piece of iron, which had to be re-maganetized every other day or so. This ‘compass’ was so valuable that any sailor who damaged it was punished by having his hands nailed to the mast!
The crude compass eventually grew into our modern steel, long-lasting compasses, by which we have navigated most of the land, sea and air space in, the world.
Do compass needles always point north? Not at all. They point to the Magnetic North Pole, which is not in the same place as the Geographic North Pole. The angle between the two is called the magnetic declination. In some parts of the world, this declination can be as much as 30 or 40 degrees off true north. But you hunters and fly-in fisherman in Northern Ontario don’t have to worry. Here the magnetic declination is just about zero. Your compass points to both the true and magnetic poles. In the Labrador, you’d have to worry.
The sailors who worked for Columbus were accustomed to have compasses pointing several degrees northeast. Suddenly, in the Atlantic, they all started pointing northwest. The sailors panicked, but Columbus was able to convince them that it was really the North Star which had shifted. Even then, people were getting hoodwinked. We still are - just watch the TV ads for a while!
The magnetic field of earth is really quite weak, and it rapidly decreases as you go off into space. The moon has no magnetism at all, so moonwalkers have to navigate by other means.
Magnetism - a useful, mysterious force. We still have a lot to learn about it.