Edward Gillin's "An Empire of Magnetism"

Since completing his DPhil in History at the University of Oxford in 2015, Edward J. Gillin has worked at the universities of Cambridge and Leeds, and is now Lecturer in the History of Building Sciences and Technology at the University College London. A cultural historian of modern science and architecture, he won the 2016 Usher Prize from the Society for the History Technology, the SAHGB's 2015 Hawksmoor Essay Medal, and was named proxime accessit for the Royal Historical Society's 2018 Whitfield Prize. In 2020, he circumnavigated Africa with a genuine 1840s' Fox-type dipping needle.

Gillin applied the “Page 99 Test” to his new book, An Empire of Magnetism: Global Science and the British Magnetic Survey in the Age of Imperialism, and reported the following:

Page 99 of An Empire of Magnetism situates the nineteenth-century study of terrestrial magnetism within a long history of scientific examination. For a book focusing on how the British government transformed this science into a truly global investigation, it is important to note that there had been voyages of magnetic research as far back as Edmond Halley’s efforts during the 1680s and 1690s. Likewise, page 99 identifies the significance of Alexander von Humboldt’s magnetic inquiries in South America and Paris during the 1790s and 1800s as a significant historical context to the British magnetic enterprise of the 1830s and 1840s, or what historian John Cawood later termed the Magnetic Crusade”. It is clear that, between the seventeenth and nineteenth centuries, the escalation in global trade and oceanic navigation stimulated a growing awareness of the erratic character of the Earth’s magnetic phenomena.

Page 99 does not reveal much of the book’s central claims: namely, that the British magnetic enterprise of the nineteenth century represented a significant moment in the relationship between the state and the natural sciences, nor that the magnetic survey was historically important in terms of its global ambition. However, the account of the three magnetic phenomena that were surveyed is critical to understanding the problem that terrestrial magnetism presented nineteenth-century scientific and political elites. Page 99’s description of magnetic “dip” (the angle at which a magnetic needle dips when pointed to the magnetic north), “intensity” (the strength of the Earth’s magnetic field), and “declination” (the difference between magnetic and geographic north) raises the threat that terrestrial magnetism presented to navigation. Without knowledge of the planet’s magnetic properties, which change over time and space, Britain’s politicians, natural philosophers, and navy authorities all feared that the rising use of iron in ship construction might undermine the accurate navigation on which the empire’s oceanic commerce and naval power depended.

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The Page 99 Test: Sound Authorities.

--Marshal Zeringue