The earth is a huge magnet, with one pole in the northern hemisphere and one in the southern. Since unlike poles attract each other, it follows that the earth's magnetic pole situated in the northern hemisphere is opposite, in kind, to the end of a magnetic needle that points to the north. From this fact, great confusion of nomenclature has arisen. We have spoken of the end of the needle that points north as - or negative. Following this nomenclature, the northern magnetic pole of the earth must be + or positive. But popular usage calls the north-seeking end of the needle the north pole and the other end the south pole. This introduces great confusion when we wish to speak of the magnetic poles of the earth. The nomenclature that we have adopted obviates this confusion.