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.
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.
Fig. 93.—Protractor Showing Degrees.
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.
