The forma fluens/fluxus formae debate concerns the question as to whether motion is something distinct from the body in motion, the flow of a distinct form identified with motion (fluxus formae), or nothing more than the successive states of the body in motion, the flow of some form found in one of Aristotle's ten categories (forma fluens). Although Albertus Magnus introduced this debate to the Latin West he drew his inspiration from Avicenna. This study argues that Albertus misclassified Avicenna's position, since Albertus could not conceptualize motion at an instant, whereas it is claimed here this was the very position Avicenna adopted. The paper includes an overview of Albertus's discussion and a brief survey of the Avicennan sources upon which Albertus drew. The heart of the paper treats Avicenna's analysis of motion at an instant. Avicenna's general argument was that since spatial points have no extremities, nothing in principle prevents a moving object from being at a spatial point for more than an instant, understood as a limit. It is then argued that Avicenna had the philosophical machinery to make sense of a limit, albeit not in mathematical terms, but in terms of an Aristotelian potential infinite.

In 1761, George III commissioned a large group of philosophical instruments from the London instrument-maker George Adams. The purchase sprang from a complex plan of moral education devised for Prince George in the late 1750s by the third Earl of Bute. Bute's plan applied the philosophy of Frances Hutcheson, who placed ‘the culture of the heart’ at the foundation of moral education. To complement this affective development, Bute also acted on seventeenth-century arguments for the value of experimental philosophy and geometry as exercises that habituated the student to recognizing truth, and to pursuing it through long and difficult chains of reasoning. The instruments required for such exercise thus became tools for manipulating moral subjectivity. By the 1730s there was a variety of established modes in which the Newtonian philosophy might be used to argue for the legitimacy of Hanoverian rule. The education of George III represents a less recognized iteration of this relationship, concerned not with public apologetics, but rather with the transformation of an ‘indolent’ youth into a virtuous monarch.

Although Henry Drummond's Natural Law in the Spiritual World (1883) is frequently cited by historians in relation to the impact of evolutionary theories on the Victorian churches, attention has not been paid to the audiences of working-class men in Glasgow for whom the papers were originally constructed. By drawing upon the notebook in which the author sketched out the series of addresses, in addition to materials relating to the interpretative habits of these audiences; I am able to consider the text as a work of practical apologetics rather than as a contribution to elite intellectual debate. This paper promises to open up new lines of enquiry with regard to the materials with which working-class audiences attempted to construct their own interpretations of contemporary scientific and religious issues. It also highlights Drummond's hitherto unrecognized use of specific practices of biblical exegesis and his debt to the work of the anatomist Richard Owen which, by keeping different forms of life distinct, and explaining organization as the effect of life already present, allowed the author to visualize the process of descent in terms of an inherent tendency to change in line with the unfolding of a pre-existing plan.

Kepler saw it as one of the chief advantages of the Copernican system that it put order into the planetary motions. Although Copernicus had indeed noted that the planetary periods increase with their distance from the sun, he did not, as far as we know, attempt to find a relationship between the two. Believing that God would not have failed to establish some mathematically precise ratio, Kepler sought from the very first to find it. Thus we see, in some of his earliest surviving letters, his attempts to relate planetary periods to the radii of their orbits using circular quadrants intersected by straight lines. Right from the beginning, Kepler gave the sun that dynamic role that was to characterize his ‘new astronomy based upon physics’. Immediately after describing the nested polyhedra that he believed determined the number and distances of the planets, he wrote:

Next, there is a moving soul and an infinite motion in the sun, and a double decrement of motion in the movables. In the first place, there is the inequality of their circuits, caused by the unequal amplitude of the orbs, which would occur even were the moving power the same in all orbs. But (2) actually this moving power (like light, in optics) is weaker the further it is from the source.

Centring on John Flamsteed (1646–1719), the first Astronomer Royal, this paper investigates the ways in which astronomers of the late seventeenth century worked to build and maintain their reputations by demonstrating, for their peers and for posterity, their proficiency in managing visual technologies. By looking at his correspondence and by offering a graphic and textual analysis of the preface to his posthumous Historia Coelestis Britannica (1725), I argue that Flamsteed based the legitimacy of his life's work on his capacity to serve as a skilful astronomer who could coordinate the production and proper use of astronomical sighting instruments. Technological advances in astrometry were, for Flamsteed, a necessary but not a sufficient condition for the advancement of astronomy. Technological resources needed to be used by the right person. The work of the skilful astronomer was a necessary precondition for the mobilization and proper management of astronomical technologies. Flamsteed's understanding of the astronomer as a skilled actor importantly shifted the emphasis in precision astronomical work away from the individual observer's ability to see well and toward the astronomer's ability to ensure that instruments guaranteed accurate vision.

In February 2020, the British Society for the History of Science hosted its first entirely digital conference via Twitter, with the dual goals of improving outreach and engagement with international historians of science, and exploring methods of reducing the carbon footprint of academic activities. In this article we discuss how we planned and organized this conference, and provide a summary of our experience of the conference itself. We also describe in greater detail the motivations behind its organization, and explore the good and bad dimensions of this relatively new kind of conferencing. As the climate crisis becomes more acute and, in turn, the pressure to reduce the carbon footprint of academic activities increases, we argue that digital conferences of this style will necessarily become more central to how academia operates. By sharing our own experiences of running such a conference, we seek to contribute to a rapidly growing body of knowledge on the subject that might be drawn on to improve our practices going forward. We also share some of our own ideas about how best to approach digital conference organization which helped us to make the most of this particular event.

In 1661 Gerard Kinckhuysen published at Haerlem an introduction to algebra written in Dutch. Because of the clarity and compactness of its presentation it was considered suitable for dissemination to a wider class of readers than those able to read Low Dutch. Nicolaus Mercator, a wellknown mathematician of German origin, who had come to England as a young man in the later 1650s, was asked by Lord Brouncker to prepare a Latin translation of it. To this Isaac Newton, at the request of Isaac Barrow and John Collins, added explanatory notes and comments, and the manuscript was sent to Collins in London on 11 July 1670. Newton's draft, though still unpublished, is preserved, but Mercator's original translation was believed to have been lost. Only recently I rediscovered it in the Bodleian in a bound volume deriving from the estate of the Oxford mathematician John Wallis, which contains several books and pamphlets once in his possession.

This article is divided into four sections:

I. A survey of Kinckhuysen's Algebra ofte Stel-konst.

II. A summary of Newton's notes and additions to it.

III. An account of the unsuccessful efforts of Collins and Newton to publish the Mercator translation, enlarged with Newton's comments—this is abstracted from Collins' correspondence with Newton, Wallis and Gregory.

IV. A description of the volume now in the Bodleian Library, press-marked ‘Savile G. 20’, which has Mercator's translation interleaved with the printed Dutch original and bound with other books once owned by Wallis.

For many of those who attended the Charles Lyell Centenary Symposium, one of the high points was the reappearance of Lyell himself (ably impersonated by John Thackray) in the lecture theatre of the Royal Institution, where some extracts from his London lectures of 1832–3 gave a vivid demonstration of his persuasive rhetoric. These extracts were also felt to illustrate Lyell's characteristic method of geological interpretation and his deeper concerns with the implications of his science, perhaps more clearly than in other published material from the earlier part of his career. At the request of several members of the symposium, I therefore give here a full version of these passages, without the ‘cuts’ and minor alterations that were necessary for the ‘performing script’. The purpose of this paper is simply to make this source-material more accessible, so that it can be used to enrich our understanding of Lyell's approach to geology at this period. I have recently published an account of the circumstances of Lyell's lectures at King's College London in 1832–3 and those at the Royal Institution in 1833, with a summary of their contents, so I shall present these fuller extracts here with the minimum of editorial notes. The two passages chosen are the longest and most continuous of those which Lyell wrote out in full rather than in note form.

Towards the end of the career of many a distinguished scientist, or shortly after his or her death, an edition of the scientist's articles is published under the title: ‘The Collected Papers of…’. While not wishing to slight either the ceremonial importance or real utility of such collections, they must be clearly distinguished from the sort of editions on which the Collected Papers of Albert Einstein is modelled. The former are primarily intended to make the published papers of a great scientist easily accessible to other scholars and students working in the same field as an aid to their research. The reader is provided with little or no help in understanding or evaluating the historical role these writings played in the development of this field, the circumstances leading to their creation, or how they fit into the life of their creator.

The early decades of the twentieth century were marked by widespread optimism about biology and its ability to improve the world. A major catalyst for this enthusiasm was new theories about inheritance and evolution (particularly Hugo de Vries's mutation theory and Mendel's newly rediscovered ideas). In Britain and the USA particularly, an astonishingly diverse variety of writers (from elite scientists to journalists and writers of fiction) took up the task of interpreting these new biological ideas, using a wide range of genres to help their fellow citizens make sense of biology's promise. From these miscellaneous writings a new and distinctive kind of utopianism emerged – the biotopia. Biotopias offered the dream of a perfect, post-natural world, or the nightmare of violated nature (often in the same text), but above all they conveyed a sense that biology was – for the first time – offering humanity unprecedented control over life. Biotopias often visualized the world as a garden perfected for human use, but this vision was tinged with gendered violence, as it became clear that realizing it entailed dispossessing, or even killing, ‘Mother Nature’. Biotopian themes are apparent in journalism, scientific reports and even textbooks, and these non-fiction sources shared many characteristics with intentionally prophetic or utopian fictions. Biotopian themes can be traced back and forth across the porous boundaries between popular and elite writing, showing how biology came to function as public culture. This analysis reveals not only how the historical significance of science is invariably determined outside the scientific world, but also that the ways in which biology was debated during this period continue to characterize today's debates over new biological breakthroughs.

Around 1960, leading figures in the international conservation circuit – such as Julian Huxley, Frank Fraser Darling and E. Barton Worthington – successfully propagated new visions about the value of undomesticated African mammals. Against traditional ideas, they presented these mammals as a highly efficient source of protein for growing African populations. In line with this vision, they challenged non-interventionist ideals of nature preservation, and launched proposals for active management through game ‘ranching’ and ‘cropping’. As such, they created a new socio-technical imaginary for Africa's future, in which the consumption of wildlife meat took up a central position. This article explores the motivations of Western conservationists for this drastic rebranding. It argues that the rationale of considering African wildlife in terms of protein played an important symbolical role at various levels. It was crucial in the reorganization of the transnational networks of conservation, but also in the boosting of their scientific reputation, in the restructuring of their institutional ties, and in their attempts to maintain an authoritative position for Western ecologists in a rapidly decolonizing world.

This essay explores the research practice of French geometer Michel Chasles (1793–1880), from his 1837 Aperçu historique up to the preparation of his courses on ‘higher geometry’ between 1846 and 1852. It argues that this scientific pursuit was jointly carried out on a historiographical and a mathematical terrain. Epistemic techniques such as the archival search for and comparison of manuscripts, the deconstructive historiography of past geometrical methods, and the epistemologically motivated periodization of the history of mathematics are shown to have played a crucial role in the shaping of Chasles's own theories. In particular, we present Chasles's approach to the ‘material history’ of algebraic symbolism and argue that it motivated and informed his subsequent invention of a novel notational technology for the writing of geometrical proofs and propositions. In return, this technology allowed Chasles to carry out a programme for the modernization of geometry in keeping with epistemic requirements he had also delineated via a form of historical writing.

Ciliary motion refers to the activity of cilia, which are hairlike structures protruding from the surface of certain epithelial cells widely found in the animal kingdom. The main function of the currents produced by ciliary beating is the moving of fluid and small particles over the ciliated surface. It is now more clearly recognized that the study of cilia is contributing to the fundamental understanding of contractility and in this way is also helping to elucidate the mechanisms associated with muscular contraction, amoeboid and intracellular movements.