Simon Naylor, <i>The Observatory Experiment: Meteorology in Britain and Its Empire</i> Cambridge: Cambridge University Press, 2024. Pp. 275. ISBN 978-1-009-20723-2. £85.00 (hardback).

With The Observatory Experiment, Simon Naylor continues his well-established work in both decentring spaces of sciences and showing how historical geographies are key to understanding particular practices and developments.Readers of Naylor's previous work will not be surprised by the methodological approach that underpins the book.Drawing together many years' detailed research on the topic, Naylor turns his attention to 'the complicated and contested refashioning of meteorology as an experimental observatory science over the course of the nineteenth and early twentieth centuries' (p.4).From Barbados to the top of Ben Nevis, Naylor draws the reader's attention to a diverse range of observatory experiments in which different cultures of meteorology were contested.Following literature on astronomical observatories, Naylor first defines an observatory by its techniques as opposed to any 'architectural expectation' (p. 7).He then equates all meteorology observatory projects in the nineteenth century and the early twentieth with observatory experiments, extending the scope of the concept introduced by Fiona Williamson.Through a focus on these observatory experiments, Naylor brings to light negotiations that took place as actors tried to grapple with fluctuating expectations for both weather science as a discipline and the associated practices/spaces.Chapter 1 takes us to sea and to a series of North Atlantic and Caribbean islands under British colonial rule that were crucial to commercial interests in the period studied.The chapter centres on meteorological cultures and the British Admiralty, particularly how ships came to be understood differently in the frameworks of Francis Beaufort, the Admiralty hydrographer between 1829 and 1855, and of William Reid, governor of the Bermuda islands between 1839 and 1846.Whereas both men agreed on the importance of meteorological observations taken in Admiralty spaces, they had different ideas both for the objectives of meteorology and for how navy ships should contribute to achieving these.The difficulties in creating, trusting, moving and monitoring observations in what Naylor calls a British colonial observatory experiment are the focus of Chapter 2. The chapter begins by highlighting both the centrality and the challenges of data mobility in the physical sciences, largely by focusing on John Herschel's writings.Naylor then details the early struggles of the Colaba Observatory in Bombay (now Mumbai) in living up to expectations of a model observatory.Later reforms that impacted this observatory reshaped networks of trust, instruments and observers as processes of computation and reduction were removed and centralized in Calcutta.