How common magnets are made.
Most of the magnets that we see are not real loadstone, but they are steel that has been magnetized by the loadstone. They are commonly made in a horse-shoe shape, as represented here. They will hold up a considerable weight of iron, and sometimes twenty-eight times their own weight; and it is curious that a magnet which holds a weight all the time will have its power increased. There is no tiring out of its power; and, on the contrary, if you give a magnet nothing to do, its power will grow weak—it will not be able to hold up so much weight as it did at first. It is for this reason that magnets are never left without a weight hanging to them.
Toy fishes and ducks moved by a magnet.
You have perhaps often been amused in making toy fishes or ducks swim about in the water with a little magnet. You have seen how readily they follow the magnet, and how quickly they spring forward to hold on to it, if you happen to put it very near them. This is because each has a little piece of steel in its mouth which is attracted by the magnet.
Strangeness of the magnetic power.
How very strange this power of the magnet is! It is not any thing that you can see, and yet there the power is. You see what it does. This unseen power in the magnet takes hold of things and draws them to it, as our hand, that we see, takes hold of things and draws them to us. How it does this we do not understand.
This power does not seem to do much at any distance from the magnet. If you hold your little magnet quite away from the toy duck or fish, it will not make it move; but bring it near, and now you see it follows the magnet all about; and if you bring it very near, the little thing, as quick as a wink, darts forward and clings to the magnet very firmly. So, too, if you bring an iron weight slowly nearer and nearer to a large magnet, there does not seem to be any influence from the magnet upon it till you bring it very near, and then all at once away goes the weight out of your hand to cling to the magnet. It is as if the magnet had very short hands that could not reach far; but so far as they do reach, they are very strong and hold fast. Whenever you get a chance to see a magnet of considerable size, you can try this experiment.
The mariner’s compass.
How to make one in a simple way.
You have heard of the mariner’s compass, but perhaps it has never been explained to you. There is a slender piece of steel in this compass which always points to the north. It is balanced on a pivot, so that it can move around easily to the one side or the other. However much it is jostled, however much you may turn the box of the compass round, this needle is always tremblingly but surely pointing one way. This needle is a magnetized piece of steel. We may consider the whole earth, with all its loadstone and iron, as a great magnet, and it is the influence of the earth upon the magnetic needle that makes it always point to the north. You can at any time make a mariner’s compass in a very simple way. All that you need is a magnetized needle, a piece of cork, and a bowl of water. Put the cork in the water, and lay the needle across it, and the needle will point north and south. You see how this is. The cork moves so readily in the water that the needle in getting right can turn it as is needed. It will turn almost as easily as the needle does on its pivot in the compasses that are made.