Each magnet has its poles, north and south--the north or south poles of one magnet repel the north and south pole of another. If a magnet be dipped in some iron filings, they will be immediately attracted to one end. Supposing this to be the north pole, each of the ends of the filings, not in contact with the magnet, will become north poles, while the ends in contact will by induction become south poles. Both will have a tendency to repel each other, and the filings will stand on the magnet. POLARITY OF THE MAGNET. The best method of proving this is to take a magnet or a piece of steel rendered magnetic, and to place it on a piece of cork by laying it in a groove cut to receive it. If the cork be placed in the center of a basin of water, and allowed to swim freely on its surface, so that it is not attracted by the sides of the basin, it will be found to turn its north pole to the north, and its south pole to the south, the same as the mariner’s compass. If you fix two magnets in two pieces of cork, and place them also in a basin of water, and they are in a parallel position with the same poles together, that is, north to north, and south to south, they will mutually repel each other; but if the contrary poles point to one another, as north to south, they will be attracted. THE MAGNETIC FISH. Fish are to be purchased at the toy-stores, by which the young “magnétique” may perform this experiment; they are made hollow, and will float on the water. In the mouth of each should be inserted a piece of magnetic wire. The angling rod is like any other rod, and has a silken thread for a line, and an iron hook also strongly magnetized. To catch the fish it is only necessary to put the hook in contact with the noses of the fish, and they will be taken without any bait. THE MAGNETIC SWAN. The figure of a swan should be cut in cork, and within its beak a small strongly magnetized piece of steel should be placed. The swan should then be covered with a coating of white wax, and fashioned further into the shape of a swan, and glass beads may be placed in its head for eyes. This should be placed in a small tub or large basin of water, and to make it swim about, you should place in a white stick about nine inches long a magnetic bar, on which the north and south poles are marked. If you wish to bring the swan towards you, present to him the north pole of the wand, if you wish it to retire, present the south pole, and thus you may direct the swan to any part you desire. TO SUSPEND A NEEDLE IN THE AIR BY MAGNETISM. Place a magnet on a stand to raise it a little above the table; then bring a small sewing needle containing a thread, within a little of the magnet, keeping hold of the thread to prevent the needle from attaching itself to the magnet. The needle in endeavoring to fly to the magnet, and being prevented by the thread, will remain curiously suspended in the air, reminding us of the fable of Mahomed’s coffin.