The explanation of the phenomenon of Brownian motion, given by Einstein in 1905 and based on the kinetic–molecular conception of matter, is considered one of the fundamental pillars (or even the main one) supporting atomism in its victorious struggle against phenomenological physics in the early years of this century. Despite the importance of the subject, there exists no specific study on it of sufficient depth. Generally speaking, most histories of physics repeat the following scheme: the discovery made by Robert Brown in 1827 (but only announced the following year), of the continuous movement of small particles suspended in a fluid did not arouse interest for a long time. Finally, at the close of the century, Gouy's research brought it to the attention of the physicists. Gouy was convinced that Brownian motion constituted a clear demonstration of the existence of molecules in continuous movement. Nevertheless, he did not work out any mathematized theory that could be subjected to quantitative confirmation. All nineteenth-century research remained at the qualitative level and yet it was able to clarify some general characteristics of the phenomenon: the completely irregular, unceasing, motion of the particles is not produced by external causes. It does not depend on the nature of the particles but only on their size. The first significant measurements, carried out by Felix Exner in 1900, appeared to deny the possibility of reconciling the kinetic theory with Brownian motion. The discovery of the ultra-microscope then allowed Zsigmondy to perceive the presence of movements, which were completely analogous to Brown's, in the particles of the colloids; these movements were rather smaller in size than those invesigated up to then. Thus Zsigmondy aroused interest in the phenomenon. Finally, in 1905, Einstein succeeded in stating the mathematical laws governing the movements of particles on the basis of the principles of the kinetic–molecular theory. The following year Smoluchowski arrived at conclusions which corresponded to Einstein's. These laws received a first, rough confirmation in the years immediately following by the work of The Svedberg, Seddig and, for some historians, Henri. Then in 1908 Jean Perrin gave it a definitive confirmation.

The magnetic circuit model acts as a unifying principle in descriptive magnetostatics, and as an approximate computational aid in electrical machine design. It was the subject of repeated rediscoveries through the period 1855 to 1886, taking different forms and being provided with different justifications but all motivated by the mathematical difficulty of existing magnetic theory. The process culminated in several competitively-slanted announcements of the principle made during 1884 to 1886, arising in connection with the already comparatively efficient designs of contemporary dynamos which made its application plausible. The preferred conceptual imagery, of induction flow against a ‘resistance’, originated in the magnetic theories of Faraday, though these underwent considerable changes before adoption.

The concept of electrical conductivity, or, as initially coined by Stephen Gray (1666–1736), ‘electrical communication’, has always been assigned an important role in the history of electrical research. Some thirty-five years after Gray's ‘electrical communication’ acquired wide attention, Priestley employed the concept of conductivity to define physical reality, thus giving a privileged position to the science he himself endeavoured to cultivate. As he argued in the introduction to The History and Present State of Electricity (1767), ‘the electrical fluid is no local, or occasional agent in the theatre of the world. Late discoveries show that its presence and effects are every where … It is not, like magnetism, confined to one kind of bodies, but every thing we know is a conductor or nonconductor of electricity’. Contemporary historians, for example, Heilbron, Home and Hackmann, link the concept of conductivity to a radical transformation of electrical research which pertained to its mode of organization and the definition of its subject-matter, and which culminated in its emergence as a distinctive branch of eighteenth-century ‘experimental philosophy’.

In 1813, two young physicists, François Delaroche and Jacques-Étienne Bérard, published a series of highly influential measurements of the specific heats of a number of common gases. Their results, obtained in answer to a prize competition set by the Institut de France, were accepted as the most accurate then available and they continued to exert a powerful, if diminishing, influence on studies of heat for the next forty years. Among the results obtained by Delaroche and Bérard were two measurements which showed that the specific heat of air decreased when the pressure was raised. This was a new and important experimental result. The ‘effect’ was found to be spurious of course (definitively by Victor Regnault as late as 1862), but in the meantime it was clear endorsement of some of the tenets of the caloric theory of heat. It could be invoked, for example, to explain the rise of temperature of a gas when it was compressed adiabatically. Robert Fox in his study of the rise and fall of the caloric theory has written:

Their error, although less than 10 per cent, was to prove one of the most influential in the whole history of the study of heat. Backed by the prestige associated with victory in the Institute's competition, the result quickly became standard and… was to mislead many calorists.

The appearance and proliferation of physics laboratories in the academic institutions of Britain between 1865 and 1885 is an established feature of Victorian science. However, neither of the two existing modern accounts of this development have adequately documented the predominant function of these early physics laboratories as centres for the teaching of physics, characteristically stressing instead the exceptional cases of the research laboratories at Glasgow and Cambridge. Hence these accounts have attempted to explain, somewhat misleadingly, the genesis of these laboratories purely by reference to the stimuli of professionalized research programmes, instead of considering the contemporary growth in demand for the professional laboratory teaching of physics. In failing to consider such physics laboratories in terms of the political economy of British education, these accounts have also failed a fortiori to correlate this development with the contemporaneous extension of laboratory teaching methods to other scientific disciplines, a movement dubbed as a laboratory ‘revolution’ by later nineteenth-century commentators.

At some point during the last two years of his life, Robert Boyle dictated to his friend, Gilbert Burnet, Bishop of Salisbury, some notes on major events and themes in his career. Some of the information he divulged in these memoranda has become quite widely known because Burnet used it in the funeral sermon for Boyle that he delivered a month after his death, at St Martin's in the Fields on 7 January 1692. In addition, these notes were cited several times by Thomas Birch in the ‘Life of the Honourable Robert Boyle’ that he prefixed to his edition of Boyle's collected works of 1744: he there describes his source as ‘Mr. Boyle's memorandums of his own life, dictated by himself to Bishop Burnet’.2 What has hitherto been virtually overlooked is that the manuscript of these notes, which is in Burnet's hand, survives among the Birch Papers in the British Library: it is this document—and particularly a substantial component of it which was publicized by neither Burnet nor Birch—that forms the starting point for this paper.

The periodical History of Science opened auspiciously in 1962 with an article by L. Pearce Williams on ‘The physical sciences in the first half of the nineteenth century: problems and sources’. He criticized the nearly exclusive reliance on printed sources then quite common in studies of Victorian science, concluded that much remained to be discovered and closed his paper with these words: What papers exist in private hands can only be guessed. I know of a trunk in an attic containing unpublished letters from Darwin, Huxley, Kolbe, Pasteur and a host of others. They are, unfortunately, not available to the scholar and there must be hundreds, if not thousands, of such boxes scattered through America and Europe. As they are discovered, catalogued and made available to scholars, the shape of nineteenth-century science will gradually lose its blurred outlines and the origins of modern science will become clear.

In 1953 Marshall Clagett presented a preliminary scheme of the medieval Latin versions of Euclid's Elements. Since then a considerable body of these texts has become available in critical editions, thanks to Clagett's labours on the Archimedean tradition and H. L. L. Busard's work on the Euclidean versions. Further, Busard, M. Folkerts, R. Lorch and C. Burnett have scrutinized the pivotal ‘second’ version of Adelard of Bath, and have thereby exposed a diversity of text forms that spells real complications for the effort to establish its provenance and use. In his recent overview of the medieval Euclidean tradition, Folkerts displays not only how these studies have filled out and expanded upon Clagett's initial framework, but also how they have compelled rethinking of some basic issues, such as on the source relations and authorship of the various versions.

Over the last forty years several historians have drawn attention to aspects of the activities of lecturers on natural philosophy in Britain in the eighteenth century. Hans and others looked at the part these lecturers played in the development of education, particularly adult education. Musson and Robinson considered the possible connection between the work of the lecturers and the growth of industry, and Inkster and others have explored the relationship between lecturers and the institutions set up to support science, especially around 1800.4 More recently, Schaffer has pointed to the parallels between the performances of the lecturers on natural philosophy and other contemporary cultural activities. As a consequence of these studies we know much more about the work of the lecturers, its significance, and, to a lesser extent, their relationship to their audience.

‘Our’ included not only Hooker and Huxley but their fellow-members of the X-Club. ‘Our time’ had been the 1870s and early 1880s. For a five-year period from November 1873 to November 1878 Hooker had been President of the Society, Huxley one of the Secretaries, and fellow X-Club member, William Spottiswoode, the Treasurer. Hooker was followed in the Presidency by Spottiswoode, and on Spottiswoode's death in 1883 Huxley was elected President. During this period other X-Club members—Edward Frankland, John Tyndall, George Busk, Sir John Lubbock, and Thomas Hirst—were ordinary members of the Council of the Society. As the Table below (p. 60) shows, there were at least three members of the X-Club on the Council of the Royal Society from November 1870 until November 1882. On eight occasions in this period there were four or more X-Club members on the Council. ‘Our time’ came to an end in 1885 when ill-health forced Huxley's retirement after only two years in the Presidency, and G. G. Stokes at last became President.

It can certainly be said that history of science has experienced a large growth in recent decades in Spain. This has occurred despite the generic term ‘history of science’ covering activities of a very varied nature and lacking an intimate relation between each other, in research as well as instruction. At present the number of publications which could fit into the frame of this branch of learning has increased remarkably and commercial publishing houses have opened their editorial lists to the publication of classics as well as to monographs on the history of science. Moreover, new specialized journals on these subjects have become popular and have joined the small number of journals which already had a certain tradition. The number of participants in the periodical congresses of the Sociedad Española de Historia de las Ciencias y de las Técnicas [SEHCYT] has risen and the number of congresses and symposia that have been held in Spain and have assembled Spanish as well as foreign historians has also increased. As another recent promising detail, we could quote the presence of history of science in the curricula of Spanish university programmes, a presence that tends to increase progressively.

Scientific textbooks are often said to deliver a stereotyped kind of knowledge, which conceals rather than reveals the real making of science. They may, however, alternatively be regarded as of peculiar interest for historians of science. An over-mechanical application of the Kuhnian concepts of ‘scientific revolution’ and ‘normal science’ can lead to the neglect of the internal dynamics of ‘normal science’. Scientific textbooks may provide a better understanding of the process of normalization in science.