THE STORY OF THE EARTH'S MAGNETIC FIELD

...time is running short for those who must comprehend our earth's magnetic field, since this field, far from being confined to the earth along, extends out into space and interacts with it."" This quotation should serve to define the scope and intent of this short book. The operative word in the title is ""story,"" for the author has made every attempt to make this difficult branch of science and its growth into a continuing, still unfinished history. Thus, the boundaries of knowledge in each given era are shown from ancient times, when the theorists speculated on the nature of lode-stone and attributed magic powers to its ability to attract iron. The invention of the compass at the end of the 13th century opened the way to further investigations and applications and by pointing out the mistakes of writers and experiments like Potrus Peregrinus and William Gilbert, the gradually emerging knowledge of the magnetic field is shown. The same method is applied to the work of the 19th century physicists on magnetism and electromagnetism, so that the great names and the explanation of their discoveries make dual impact. Mrs. Beiser's ability to make the difficult comprehensible has been demonstrated in the story of Cosmic Rays and Physics for Everybody, written with her husband.