A number of very pleasing experiments may be performed by means of the Magnetic Wand. It is made out of a rod of hard wood, about ten inches long by a third of an inch thick. A hole is to be drilled into this rod, and in the hole is to be placed a strongly magnetised steel wire. Two small knobs should then be placed upon the reverse ends of the wand, and, in order that it may be readily known at which end of the wand is the attractive and at which end the repellent point of the magnetised wire, the knobs ought either to be differently carved or one or both of them should bear some distinctive mark. The letters N and S are suitable as specifying the north and the south poles, by which terms the opposite ends of the magnetised wire are scientifically expressed. The wand so made is complete, and by holding one or other of its ends to the tips of small articles floating in water, made after the manner described in the manufacture of the Magnetic Swan, such articles may be made to either follow after or swim from the wand according as it is the north or the south pole which is held out.
It is an easy matter to magnetise a bit of steel wire, and under this heading of how to make a Magnetic Wand, a few hints on magnetising common objects of steel and iron will not be out of place.
An ordinary poker may be magnetised in a very simple manner. Hold it in the left hand, pointing it somewhat inclined from the perpendicular, so that the lower end is towards the north, then strike the poker several times smartly with a large iron hammer, and to a slight extent it will then be found to possess the powers of a magnet. Another method is as follows:—Get an old large iron poker, and a similar pair of tongs, such as may be found forming a part of the set of fire-irons formerly supplied for kitchen use. Fix the poker upright, and hold to it a bar about three inches long of soft steel, which should be about a quarter of an inch broad, but not more than a twentieth of an inch in thickness. Make on one end of the steel a mark, and let that end be held downwards. The steel should not be held to the poker with the hand, but should be suspended on a piece of silk held in the left hand, and so suspended as to touch the poker. Then grasp the tongs a little below the middle with the right hand, and keeping them as nearly vertical as possible, rub the steel bar with the lower end of the tongs, from the marked end of the bar to its upper end about ten times on each side of it. By this means the bar will receive enough magnetism to enable it to lift at the marked end a small steel key. Or if the bar so magnetised be suspended at its centre, and made to rest on a point, the marked end will turn to the north.
Steel fireirons which have remained untouched during the summer period, and have at the same time remained resting on the fender, in an ordinary living-room, will be found after a few months to have become possessed of magnetic properties.
A common sewing needle is readily magnetised by passing, when gently pressed against it, the north pole of a magnet from the eye to the point of the needle. After the end of the needle has been reached, the magnet must not be passed back along it again to the eye, or the effect will be destroyed; but the effect is increased if the magnet is passed several times in succession from the eye to the point. A needle so magnetised may be used in the place of the magnetised wire required for a small Magnetic Wand.
MAGNIFYING PINHOLE.
See "[Microscope (Toy)]."
MECHANICAL BUCEPHALUS.
See "[Pegasus in Flight]."