also attracts with its extremities the contrary poles of other particles. Ex. III. If I shake some iron filings through a gauze sieve, upon a paper that covers a bar magnet, the filings will become magnets, and will be arranged in beautiful curves. James. Does the polarity of the magnet reside only in the two ends of its surface? Tutor. No: one half of the magnet is possessed of one kind of polarity, and the other of the other kind; but the ends, or poles, are those points in which that power is the strongest.. DEF. pole to the other is called the axis of the magnet, cikge CONVERSATION III. The Method of making Magnets TUTOR. I have already told you that artificial magnets, which are made of steel, are now generally used in preference to the real magnet, because they can be procured with greater ease, may be varied in their form more easily, and will communicate the magnetic virtue more powerfully. Charles. How are they made? Tutor. The best method of making artificial magnets is to apply one or more powerful magnets to pieces of hard steel, taking care to apply the north pole of the magnet or magnets to that extremity of the steel which is required to be made the south pole, and to apply the south pole of the magnet to the opposite extremity of the piece of steel. James. Has a magnet, by communicating its properties to other bodies, its own power diminished? Tutor. No, it is even increased by it. A bar of iron, three or four feet long, kept some time in a vertical position, will become magnetic, the lower extremity of it attracting the south pole, and repelling Y 2 1 the north pole. But if the bar be inverted, the polarity will be reversed. 1 : Charles. Will steel produce the same effects? Tutor. It will not; the iron must be soft, and hence bars of iron that have been long in a perpendicular position, are generally found to be magnetical, as fire irons, bars of windows, &c. If a long piece of hard iron be made red hot, and then left to cool in the direction of the magnetical line, it usually becomes magnetical. Striking an iron bar with a hammer, or rubbing it with a file, while held in this direction, renders it magnetical. An electric shock, and light ning, frequently render iron magne tic. James. An artificial magnet you say is often more powerful than the real one; can a magnet, therefore, communicate to steel a stronger power than it possesses? Tutor. Certainly not but two or more magnets, joined together, may communicate a greater power to a piece of steel, than either of them possesses singly. Charles. Then you gain power according to the number of magnets made use of? Tutor. Yes; very powerful magnets may be formed by first constructing several weak magnets, and then joining them together to form Y 3 |