Make a little figure of cork, in the shape of a dancing mountebank, sailor, etc. In this figure place a small hollow cone, made of thin leaf brass. When this figure is placed upon any jet, such as that of the fountain recommended to be constructed, it will be suspended on the top of the water, and perform a great variety of amusing motions. If a hollow ball of very thin copper, of an inch in diameter, be placed on a similar jet, it will remain suspended, turning round and spreading the water all about it. MAGNETISM. The attractive power of the loadstone has been known from a very remote period. The natural magnet appears native in a gray iron ore in octahedral crystals, composed of 168 parts of iron, and 64 parts of oxygen. Its properties seem to have been studied in Europe during the dark ages and a directive power is alluded to by Cardinal James de Vitri, who flourished about the year 1200, who observed that it was indispensable to those who travel much by sea. In modern times, the history as well as the nature of the magnet has engaged remarkable attention; and it has been determined beyond all dispute that the magnet was used by the Chinese under the name of the _tche-chy_ (directing stone) about 2604 years before Christ. It passed from them to the Arabs, and was first used in Europe after the crusades; and Ludi Vestomanus asserts that about the year 1500 he saw a pilot in the East Indies direct his course by a magnetic needle like those now in use. TO MAKE ARTIFICIAL MAGNETS. This may be done by stroking a piece of hard steel with a natural or artificial magnet. Take a common sewing needle and pass the north pole of a magnet from the eye to the point, pressing it gently in so doing. After reaching the end of the needle the magnet must not be passed back again towards the eye, but must be lifted up and applied again to that end, the friction being always in the same direction. After repeating this for a few times the needle will become magnetized, and attract iron filings, etc. HOW TO MAGNETIZE A POKER. Hold it in the left hand in a position slightly inclined from the perpendicular, the lower end pointing to the north, and then strike it smartly several times with a large iron hammer, and it will be found to possess the powers of a magnet, although but slightly. TO SHOW MAGNETIC REPULSION AND ATTRACTION. Suspend two short pieces of iron wire, so that they will hang in contact in a vertical position. If the north pole of a magnet be now brought to a moderate distance between the wires, they will recede from each other. The ends being made south poles by induction from the north pole, will repel each other, and so will the north poles. This separation of the wires will increase as the magnet approaches them, but there will be a particular distance at which the attractive force overcomes the repulsive force of the poles, and causes the wires to converge. NORTH AND SOUTH POLES OF THE MAGNET.