the novel style, “Notes” are listed by chapter and page number at the end of the book, with a phrase from the text reproduced instead of a superscript. The problem with this approach is that you don’t see these notes when reading the chapter. There are 276 such “notes”. Chapters on classical theory (perhaps considered too“dry”) are interspersed with less formal chapters, presumably to retain the attention of the reader. For example, in the first serious chapter, on atomic structure, we are urged on by the words“if we can wade through a few more points here, you’ll get to one of the ideas that lies at the heart of magnetism”. In addition, the author admits to not understanding electron orbits, with“To me it sounds like gobbledygook”(my italics). Even though it is not an academic book, in my opinion it could have benefitted from some illustrations. Turner, by way of contrast, has 56 illustrations including detailed sketches of the prominent players that brings them alive. Mitchell’s alternative to this is graphic, sometimes personal, descriptions of the protagonists. One of many examples of this are four pages devoted to the life of Inge Lehmann (as compared to one page by Turner). As a way of making the story more real and personal, some of these famous contributors to the subject are introduced by present-day advocates whom Mitchell has met in their offices, or at a conference in Nantes. Generally, these“guides”to protagonists are described in surprisingly familiar detail. The name of one of these advocates, Jacques Kornprobst, is the first two words of Chapter 1. He was“sporting a thick, off-white cable-knit sweater the same hue as his rakish hair, … ”. He is the “guide”for Bernard Brunhes, who was the first to uncover evidence of pole reversals.The story of Brunhes is told in five typically short, alternating chapters; numbers 1, 3, 5, 7, and 9. While they can be read as one continuous story they are, however, interspersed with chapters on various theoretical and unconnected topics. This is one of the author’s apparent efforts to present the theory in small chunks so as to make it more palatable. Mitchell’s views on geophysicists, say by way of contrast to her descriptions of particle physicists and astrophysicists, is that many geophysicists seem“to be as much at home hacking a piece of rock … as crunching complex numerical simulations through supercomputers”. She does recognise other branches of the profession such as seismology, volcanology, etc. Insurance against the risk to civilisation posed by disruption of the magnetic field is given a chapter. This is an appropriate consideration at this time, and one which is not likely to be dealt with in a more academic book such as Turner’s. The second-last chapter titled “Trout Noses and Pigeon Beaks” discusses magneto-reception, the study of what enables animals to navigate using the magnetic field. As this is a subject of personal interest, I can attest that it is well summarised. Mitchell’s references in the (worrisome) “Notes” range only up to the year 2009 on this subject, but research in this area continues to the present day. Apart from the above two extra short chapters, the remaining four in Part 4 are concerned mainly with NASA projects as described to Mitchell by Daniel Baker, who is“tall and broad- shouldered with straw-straight, gingery hair”. These are the projects designed to improve understanding of the external magnetic field. The closing chapter discusses the effects of possible increased radiation on humans from a weakening field. As a result of all her discussions with Baker and many others, Mitchell is left to contemplate the effects of“All these mysterious goings-on below the surface of this spinning magnet we live on”. An entertaining read! Roger Henderson ASEG History Committee Chair 31 PREVIEW Book review FEBRUARY 2019