Such a needle, if the box containing it be placed on a level surface, will generally be observed to vibrate more or less, till it settles in such a direction that one of its extremities or poles will point towards the north, and the other consequently towards the south. If the position of the box be altered or reversed, the needle will always turn and vibrate again, till its poles have attained the same direction as before.
Does the compass needle always point exactly north and south?
It does not; its natural direction is towards the north and south poles, but it seldom points due north or south.
Who first discovered the fact that a magnet would invariably point to the north and the south, and made use of this knowledge in constructing a compass?
It is claimed to have been discovered by the Chinese: it was known in Europe, and used in the Mediterranean, in the thirteenth century.
How were the compasses of that time constructed?
They were merely pieces of loadstone fixed to a cork, which floated on the surface of water.
Is the earth itself supposed to be a magnet?
It is undoubtedly a great magnet.
Is iron under certain circumstances rendered magnetic by the inductive action of the earth’s magnetism?