The bulk of this address concerns itself with the extent to which professional scientists were involved in popular science writing in early twentieth-century Britain. Contrary to a widespread assumption, it is argued that a significant proportion of the scientific community engaged in writing the more educational type of popular science. Some high-profile figures acquired enough skill in popular writing to exert considerable influence over the public's perception of science and its significance. The address also shows how publishers actively sought ‘expert’ authors for popular material, but at the same time controlled what was published in accordance with their perception of what would sell. At a more popular level of writing there were many semi-professional authors who, while not active scientists, exploited close contacts with the scientific community. Here there was a strong emphasis on the practical applications of science.

The address concludes by suggesting parallels between popular science writing in this period and the present state of popular writing about the history of science.

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.

Freemasonry was the most widespread form of secular association in eighteenth-century England, providing a model for other forms of urban sociability and a stimulus to music and the arts. Many members of the Royal Society and the Society of Antiquaries, for instance, were Freemasons, while historians such as Margaret Jacob have argued that Freemasonry was inspired by Whig Newtonianism and played an important role in European Enlightenment scientific education. This paper illustrates the importance of natural philosophy in Masonic rhetoric and utilizes material from Masonic histories, lodge records and secondary works to demonstrate that scientific lectures were indeed given in some lodges. It contends, however, that there were other sources of inspiration for Freemasonry besides Newtonianism, such as antiquarianism, and that many other factors as well as the prevalence of Masonic lodges determined the geography of English scientific culture. Although the subject of Freemasonry and natural philosophy has great potential, as Jacob has demonstrated so well, much further work, especially in the form of prosopographical studies of provincial lodges, is required before the nature of the relationship between the two can be fully appreciated.

This paper examines the activities of the Alsatian physicist–engineer and philosopher Gustave-Adolphe Hirn, whose contribution to thermodynamics and the metaphysical interpretation of heat theory are rather neglected parts of the history of French thermodynamics. The industrial environment in which Hirn was reared, and in which he worked, turned his thoughts to an investigation of thermal phenomena in conjunction with their relevance to the industrial needs of his factory. Nurtured in the intellectual environment of Colmar, Hirn also developed a deep sense of morality that was bound to the Christian world view. His work on heat led him to a generalized metaphysics based on the notion of force. However, despite important work on friction and his ‘independent’ discovery of the mechanical equivalent of heat, Hirn never felt that his work received its due recognition from his contemporaries. Without attributing this negligence solely to Hirn's relative isolation in Alsace and to the absence of formal institutional affiliations, the paper suggests that it was Hirn's particular scientific practice that was at odds with well-established practices employed by other French scientists and engineers.

This article assesses the reputation of Mary Somerville in the 1830s and suggests that critical confusion over her status in the changing world of early nineteenth-century science is not new. Drawing on Somerville’s own writings, contemporary newspaper and periodical reviews, political debates and unpublished manuscripts, Somerville's ‘uniqueness’ as a public figure is examined through the eyes of both the nascent scientific community of the time as well as the wider audience for her work. Somerville's status as a popularizer and an educator is more complicated than may have previously been assumed and can be both confirmed and undermined by an analysis of contemporary public opinion. Although her works were directed at the public who indirectly paid her pension for services to science, Somerville's private and published comments about and within her writings offer an alternative interpretation. Despite an apparent turn to more popular works in order to bolster her finances, Mary Somerville relished the specialist aspect of her writings and valued the difficulties which prevented the ordinary reader from obtaining ultimate insight into celestial mechanics.