عنوان مقاله [English]
نویسنده [English]چکیده [English]
The magnetic properties of some iron minerals were known since very old times. In Chinese legends, there is reference to a very simple magnetic needle that was used to determine orientations on the earth four thousand years ago. In Europe, the properties of magnetic needle were known since the 11th century, and in the 13th century they built the first simple compass. The invention of compass in an era that saw numerous geographical explorations helped geographers greatly, and since then, the study of earth's magnetism has been considered.