This rich collection of essays concentrates on underexplored aspects of the development of scientific naturalism in the nineteenth century. The concept has generally been seen through the lens of the biological sciences and this book redresses the balance, examining in particular the impact of the physicist John Tyndall and of that individualistic and cussed figure Herbert Spencer, a close friend of Tyndall. The three sections of the book deal respectively with Tyndall himself, with the changing nature of the movement of scientific naturalism, and with modes of communication and discourse about science.

In the first section Elizabeth Neswald addresses Tyndall's relative silence on the second law of thermodynamics, Joshua Howe neatly punctures the heroic tale of climate science, and Jeremiah Rankin and Ruth Barton contrast Tyndall and Lewes, both scientific naturalists, as examples of ‘professional’ and ‘citizen’ science in action. In the second section Michael Taylor explores the impact of Spencer, following which three lesser-known figures are examined: William Kingdon Clifford and the evolutionary nature of mathematical knowledge, by Josipa Petrunic; William Huggins, the astronomer who ‘converted’ to evolutionary naturalism, by Robert Smith; and Alfred Newton, whom Jonathan Smith sees more as concerned with advancing science itself than as sharing the agenda of the scientific naturalists of secularizing society. In the final section Janet Browne highlights the value of letters and correspondence networks to the historian, with the first of the planned sixteen volumes (or more) of Tyndall's correspondence due in 2015; Tyndall wrote private letters, official letters, scientific letters to individuals and journals, and letters to newspapers such as The Times (in profusion) and the Pall Mall Gazette. Melinda Baldwin, in the following chapter, analyses the revealing Tyndall–Stokes correspondence. In the final chapter Bernard Lightman, telling the tale of the Metaphysical Society, places the debates between the scientific naturalists and the Christian metaphysicians in the wider cultural contest over the nature and power of science and those who claimed to speak for it.

The authors throw light not only on the evolution of scientific naturalism as an organizing concept and belief system, but also on the evolution of the views of individuals who espoused some version of it at some point in their lives. Of course Tyndall can be claimed for the scientific naturalists, but these essays illustrate the diversity within that category, and too great a focus on it also risks downplaying other aspects of character and belief. Tyndall gave up churchgoing in his mid-twenties but he remained in regular friendly contact with many clerics, once spending two weeks traversing the Alps with the Reverend Arthur Girdlestone, a man who would gather his party around him on the glacier prior to an expedition to pray for safe deliverance. Many descriptors could be applied to Tyndall with different emphases at different times of his life – poet, romantic and pantheist being just three. Perhaps, indeed, Tyndall was closer to his friend Spencer in his transcendentalist influence and mindset than would appear from interpretations to date. Consciousness, not explicitly discussed in this volume, was an important concern and mystery to Tyndall, signifying possible limits to scientific understanding. So too was the origin of the complexity of living things. As Tyndall put it in his memorable late poem ‘A Morning on Alp Lusgen’, ‘Whence the craft which shook these gentian atoms into form?’ That is a question the scientific naturalists could not answer. Today's rabid scientific naturalists may dispute that, but they could usefully read these essays as a challenge to the ahistoricity of much current analysis. I fear they may not, though that is no criticism of an excellent book, and one can confidently expect that the arguments played out in this volume will continue to be replayed in changing social, political and religious settings.