At the north magnetic pole the needle will stand straight up and down in a line with the axis of the Earth. The dip, therefore, of the needle at any place on the Earth’s surface is just about that of the latitude of the place where it is used. Dipping needles are also used by miners for finding iron ores. [Illustration: FIG. 92.—DIPPING NEEDLE COMPLETE.] To make a dipping needle, slip a small cork over a knitting needle and push a sewing needle through the cork at right angles to the knitting needle, as shown in Fig. 91. Now lay the sewing needle with its ends on the edges of two tumblers, and see that the knitting needle is perfectly balanced. This done, magnetize the knitting needle by rubbing one end on the north pole of a steel magnet and the other end on the south pole of the magnet. Make a little wood stand as shown in Fig. 92 and place the ends of the sewing needle on the wood supports. [Illustration: FIG. 93.—PROTRACTOR SHOWING DEGREES.] [Illustration: FIG. 94.—EARTH SURFACE DIVIDED INTO DEGREES.] The latitude running through the middle of the United States is about 40 degrees north of the equator and if you live in this latitude the dip of your needle will be about 40 degrees from the horizontal. [Illustration: FIG. 95.—PROTRACTOR SET BY DIPPING NEEDLE SHOWING LATITUDE.] =How to Find Latitude.=—The _latitude_ of a place on the Earth’s surface is its distance north or south of the equator. This distance is usually measured in _degrees_ of a circle, instead of in miles. The equator is called 0 (zero) degrees, and the north and south poles are 90 degrees from the equator, as shown in Fig. 93. If you are in Philadelphia, Pennsylvania, or Quincy, Illinois, or Tehama, California, you are in latitude 40 degrees. If you are in Bangor, Maine, St. Paul, Minnesota, or Portland, Oregon, you are in latitude 45 degrees, or just halfway between the north pole and the equator, as Fig. 94 shows. (1) An easy way to find roughly the latitude of a place, that is, its distance from the equator, is to use a dipping needle and a _protractor_. To make a protractor cut out a semi-circle of stiff, white cardboard, just the size shown in Fig. 93, and mark the figures on the edge and draw lines from the edge to the center point exactly as in the picture. [Illustration: FIG. 96.—TWO STICKS SCREWED TOGETHER.] [Illustration: FIG. 97.—TWO STICKS ACROSS BUCKET OF WATER.] Now place your dipping needle on a level board or table and set the center of your cardboard protractor in line and on a level with the axis of the needle, as shown in Fig. 95. Whatever line on the protractor the dip of the needle takes the degree marked on the edge of the protractor will be the magnetic latitude you are in.