Ans. Magnets have two opposite kinds of magnetism or magnetic poles, which attract or repel each other in much the same way as would two opposite kinds of electrification. =Ques. What is the nature of each kind of magnetism?= Ans. One has a tendency to move toward the north and the other toward the south. [Illustration: FIGS. 94 to 96.--Simple _bar magnet_ and _horse shoe magnet_ with _keeper_. These are known as _permanent magnets_ in distinction from _electromagnets_. The horse shoe magnet will attract more than the bar magnet because both poles act together. A piece of soft iron, or keeper is placed across the ends of a horse shoe magnet to assist in preventing the loss of magnetism.] [Illustration: FIGS. 97 and 98.--Horizontal magnetic needle, and magnetic “dip” needle. A magnetic needle consists of a small bar magnet, supported upon a pivot or suspended so that it is free to turn in a horizontal or vertical plane. The form of magnetic needle illustrated in fig. 97 is arranged to show the magnetic meridian; the needle moves upon a perpendicular axis or pivot _ab_. In fig. 98, the needle _sn_ turns upon a horizontal axis _ab_. This needle indicates the dip or inclination, that is, the angle which it makes with the horizontal plane, due to the fact that in most places the lines of force are not horizontal. In the northern hemisphere the N pole of the needle is depressed, in the southern hemisphere the S pole is similarly affected. When used, the dip needle must be set so that the plane in which the needle swings contains the magnetic meridian, as indicated by the horizontal needle.] =Ques. Where is the magnetism the strongest?= Ans. In two regions called the _poles_. =Ques. Describe the distribution of magnetism in a long shaped magnet.= Ans. The strongest magnetism resides in the ends, while all around the magnet half way between the poles there is no attraction at all. [Illustration: FIG. 99.--Magnetic poles. If a bar magnet be plunged into iron filings and then lifted, as illustrated in the figure, a mass of filings will cling to the ends of the magnet but not to the middle. The ends are called the _poles_ of the magnet.] =Ques. How are the poles designated?= Ans. They are called the _north pole_ and the _south pole_. =Ques. What is the distinguishing feature of each?= Ans. The north pole points approximately to the earth’s geographical north, while the south pole of a magnet points approximately to the earth’s geographical south. The north pole is the positive (+) pole and the south pole is the negative. The north and south poles were formerly called in France, the austral and boreal poles respectively.