North Pole, South Pole

November 15, 2010

In her debut, Turner (Geophysics/Victoria Univ., New Zealand) negotiates the slippery ground between hard and popular science in this story of magnetism.

The author begins with the ancient Greeks, as well as the Chinese, who used the compass in the art of feng shui, and continues through its deployment by Europeans (who may have independently discovered the tool) in the creation of portolan charts and rhumb lines, which allowed mariners to move beyond known coastlines. Despite these advances, the idea of magnetism was still little-understood. Enter the physicists and mathematicians, and here Turner takes no prisoners in her popular audience. To appreciate that the Earth's magnetic field is a "geocentric axial dipole," readers will have to dig through discussions of physics, chemistry, electricity, precession, nutation, perturbation, seismology and the Chandler wobble. Some of the author's knottier sentences—e.g., "the ratios of rough measurements of magnetic field strength (or, more precisely, dipole moment) and rotational angular momentum came very close to the square root of the gravitational constant—the constant, G, in Newton's law of gravitation, which had eventually been measured by Henry Cavendish—divided by the speed of light"—may be a bit much for general readers, but for the most part Turner achieves an engaging appreciation of science at work discovering the mysteries of magnetism. By the time she hits continental drift, polar wander and the geodynamo theory, readers may even understand what she means by saying that "the twisting and shearing caused by convection and the rotation of the Earth convert toroidal field lines into poloidal field lines and vice versa."

A mostly smooth explanation of a rarefied area of science.

(COPYRIGHT (2010) KIRKUS REVIEWS/NIELSEN BUSINESS MEDIA, INC. ALL RIGHTS RESERVED.)

March 15, 2011

Turner (senior lecturer, Victoria Univ., Wellington, New Zealand) has written a highly accessible history of the discovery and understanding of Earth's magnetism. She covers all of the major historical steps in the discovery of magnetism and presents her information in such a way that makes potentially difficult scientific concepts easy to understand and even entertaining to read. Human drama is also at play here, as many scientists throughout history have struggled to discover magnetism's many secrets. VERDICT Libraries that own Gerrit Verschuur's Hidden Attraction: The History and Mystery of Magnetism may not need to add this work, but Turner's title is recommended for popular history of science collections as well as for all readers looking to understand how we came to our current understanding of magnetism. Since it also involves long sea voyages, this book will also be an enjoyable read for those interested in the history of navigation.--Eric D. Albright, Tufts Univ. Hirsh Health Sciences Lib., Boston

Copyright 2011 Library Journal, LLC Used with permission.