Extreme variation in the meaning of the term “species” throughout the history of biology has often frustrated attempts of historians, philosophers and biologists to communicate with one another about the transition in biological thinking from the static species concept to the modern notion of evolving species. The most important change which has underlain all the other fluctuations in the meaning of the word “species” is the change from it denoting such metaphysical entities as essences, Forms or Natures to denoting classes of individual organisms. Several authors have taken notice of the role of metaphysics in the work of particular biologists. An attempt will be made in this paper to present a systematic investigation of the role which metaphysics has played in the work of representative biologists throughout the history of biology, especially as it relates to their species concepts.

Almost traditionally, it seems, accounts of the development of the concepts of work and energy have tended to describe them within the classical framework of Newtonian mechanics. They are seen as the end products of the celebrated vis-viva dispute in the eighteenth century: the outcome of a debate within the confines of the science of rational mechanics. I would like to suggest that this may be to take too narrow a view of the case. It is to project backwards our present specialist arrangement of scientific knowledge, our present divisions between the sciences, and to assume that past development was strictly guided by these divisions. And this is to make questionable historical and sociological assumptions.

The slow emergence of Dalton's chemical atomic theory has long been a considerable puzzle to historians of science The lengthy delay between Dalton's early work on mixed gases (September 1801) and particle weights (September 1803) and the eventual publication of the first part of his New System of Chemical Philosophy (June 1808) has called forth a variety of explanations. It is now more than half a century since A. N. Meldrum stressed

“…the efforts Dalton had to make, in order to arouse attention to the importance of his ideas regarding atoms. For some nine years (1801-1810), if not longer, he endeavoured to spread abroad his ideas, both by private communications and publicly, by his writings and by lectures in various parts of the country…

“Dalton's chemical theory was formed by the 6th September 1803, and he proceeded forthwith to extend and apply it, and make it known in every direction…”

And though Meldrum's view is now no longer accepted, no systematic and detailed account of Dalton's activities over these years is available to replace Meldrum's assertions.

By an ancient and honourable tradition, which began last year when I spared you this exercise, the President gives a Presidential Address only once during his term of office, on retirement. A presidential address in the summer season is a privileged occasion. Coming at the end of an active day, it is not the moment for a massive account of research. Rather it is an occasion when one may indulge with privilege in some directed impressionism, and that is what I propose to do.

In most of the more lively fields of physical enquiry in the first three decades of the seventeenth century, a striking contrast may be observed between the antiquity of the problems attacked, and the innovatory procedures applied to solve them. None of these questions, inherited from a past now remote, seemed more pressing than the time-honoured controversy of the plenum versus the vacuum, especially as the concept of the atomic structure of matter was so closely associated with the existence of the void. The more one studies the arguments produced at that time, the more one will be impressed with the value and importance, for the vacuists and the atomists, of the Pneumatics of Hero of Alexandria. When we read Galileo's explanation of combustion, “the extremely fine particles of fire, penetrating the narrow pores of the metal (too small to admit even the minutest particles of air or of many other fluids) would fill the minute intervening vacuum, and would set free these minute particles from the forced attraction which these same vacua exert’, we can hear clear echoes of Hero's account of disseminated micro-vacua. Now Hero's work is clearly divided into two sections: a theoretical preface and a collection of 78 “pneumatic devices”. One might be tempted to claim that he, rather than his fellow-atomist Lucretius, inspired the first tentative syntheses of seventeenth-century atomism but it would still be necessary to agree that his chief contributions to the achievements of that generation lie in the experimental techniques which they derived from his instrumentation. Were it not for the popularity of his pneumatic demonstrations, he could never have won such a great reputation as a natural philosopher. Without that reputation, his opinions on this topic would not have been valued as almost equal to those of the mighty Aristotle, especially since he was so decidedly in the minority.

Apart from statics, about which I shall say nothing, there were three chief centres of interest in mechanics in the 1660's:

(1) the motions of pendulums;

(2) the laws of motion;

(3) the free fall of heavy bodies and the motion of projectiles.

In the first the influence of Huygens was dominant; I have placed it so because it was of very lively contemporary concern. The second area of interest descended partly from Galileo and partly from Descartes; the third from Galileo alone. Perhaps one should consider adding a fourth area, the investigation of central forces, but this in fact did not attract much attention as yet.

In France, as in other European countries, especially Britain and Germany, the nineteenth century was a period of great progress and achievement in science. This would still have been true if Claude Bernard and Louis Pasteur had been the only outstanding French scientists of the nineteenth century, whereas there were, of course, many others apart from an impressive number of brilliant French mathematicians. Nevertheless, although it was a great century for French science there was perhaps something rather disappointing about it, and something rather ingrowing about the attitude of French scientists towards scientific developments in other countries. For example, the French took it hard that the creator of the theory of evolution should have been an Englishman, remembering too late Darwin's predecessor Lamarck, and they certainly were very slow in accepting Darwin's theory of evolution.1 Again, the French may have felt that after the important contributions of French scientists such as Coulomb, Poisson, Biot and, above all, Ampère, the theory of electricity and magnetism which is today principally associated with the names of Faraday and Maxwell should have been created by a Frenchman. Once again this new theory was only accepted very slowly and hesitantly, and even unwillingly, in France—one thinks, for example, of the criticisms levelled at the theory by Pierre Duhem in his “The Aim and Structure of Physical Theory”.2 Of course it might be that if one knew how to weigh properly the various achievements of French scientists in different branches of science one would find that, allowing for her rather static population during the nineteenth century, the total contribution of France compared well with those of Britain and Germany. Nevertheless, in one case at least, that of theoretical physics, there seems to have been an unmistakable failure to live up to the promise of the beginning of the century. The purpose of this paper is to advance possible reasons to explain this failure.

The most perplexing aspect of Galileo's work in physics is without doubt the sharp distinction one can draw between his essentially dynamic studies in such juvenilia as De Motu and the consciously kinematical approach of his later output—particularly the Two New Sciences. Whether one chooses to call this a shift from the “why” of motion to the “how”, or, as I should prefer, a shift from dynamics to kinematics, there can be no denying its existence. The Galileo who wrote that “The present does not seem to be the proper time to investigate the cause of the acceleration of natural motion …” is, on the face of it, a very different man from the one who had earlier written almost an entire treatise on precisely this topic.

During his long life Alexander von Humboldt (1769–1859) was mainly connected with three European countries: Germany, France and Russia; nevertheless, he had many scientific and personal relations with England, with British scientists, and with other distinguished citizens of Great Britain. Thus Humboldt's life provides an interesting example of international scientific relations in the nineteenth century. The present paper offers a brief account of this universal and versatile scientist's relations with England in particular.

This paper summarizes ideas about the nature of gases proposed during the period following the discovery of Boyle's law. Particular stress is laid on the hypotheses of the Bernoullis, and later, on the equally speculative work of Herapath. Reasons for the success of Herapath's theory, and the neglect of Daniel Bernoulli's are discussed, but it has not been thought necessary to take the story beyond the initial acceptance of Herapath's theory by J. P. Joule, because the paper is concerned only with the antecedents of the modern kinetic theory.

From the very day in 1686 when Edmond Halley placed Book I of the Principia before the Royal Society, Robert Hooke's claim to prior discovery has been associated with the law of universal gravitation. If the seventeenth century rejected Hooke's claim summarily, historians of science have not forgotten it, and a steady stream of articles continues the discussion. In our own day particularly, when some of the glitter has worn off, not from the scientific achievement, but from the character of Newton, there has been a tendency vicariously to atone for the treatment Hooke received. The judgement Lohne cites with approval from Vavilov appears to summarize the current estimate of the issue—in the seventeenth century only Newton could have written the Principia; nevertheless Hooke first sketched out its programme. What with all the knocks he has received both alive and dead, one feels guilty (and perhaps superfluous) in assuming the role of “debunker” at this late date. Apologetically draped in sackcloth then, head covered with ashes (and with whatever it is one dons for superfluity) I venture softly to suggest that Hooke has received more than his due. There is no question here of justifying Newton's behaviour toward Hooke. Wholly lacking in generosity as it appears to me, Newton's behaviour neither deserves nor can receive justification. The question turns rather on Hooke's scientific theories. Granting always his lack of demonstrations, historians have been prone to interpret his words in the light of Newton's demonstrations. A close examination of Hooke's writings does not sustain the interpretation. Contrary to what is generally asserted, he did not hold a conception of universal gravitation. And if he announced the inverse square relation, he derived it from such a medley of confusion as will not allow his claim to priority.

Johann Wolfgang Goethe* (1749–1832) believed that in 1784 he demonstrated the presence of the intermaxillary (premaxillary) bone in man, and that after a certain amount of opposition professional anatomists accepted his findings. This paper tries to show what the anatomical facts are, what it was that Goethe discovered, how his beliefs about his contribution and influence arose, and how his discovery is related to his general scientific aims and methods.

This essay concerns an aspect of the speculative contributions of J. J. Thomson to a field of physics somewhat removed from that upon which his popular fame and scientific eminence were alike founded. He published a number of statements in the period 1903–1910 advocating a discontinuous structure of the electromagnetic field. His unorthodox conception of the field was based upon the presumed discreteness of Faraday's physical lines of electric force. While his ideas led to significant experimental work, they were not brought together in the form of a completed theory. It was at this same time that the quantum theory was independently evolving notions of a structure of the field, and Thomson's efforts at developing a theory of light were diverted into a protracted criticism of the hypothesis of quanta. In 1924–1936 he returned to the subject of the structure of light, but these latter speculations no longer had much relevance to contemporary physical thought.

De generatione was the last of the three works published by William Harvey during his lifetime. Although this work on generation was most ambitious, being the product of prolonged and detailed researches, it has received relatively little attention from modern writers. It is generally felt that this work, like William Gilbert's De mundo, departs significantly from the more pronounced empirical approach to science which characterized Harvey's first publication, De motu cordis. De generatione shows that Harvey regarded reference to teleological and vitalistic principles as necessary for the solution of crucial problems in biology. In this respect he differed from his contemporaries, the iatrochemical and iatromechanical physiologists, whose non-teleological approach seems, at least superficially, to be in sympathy with the modern biological tradition. The structure and content of De generatione are so evidently determined by Aristotle's biological writings, that the work is used to illustrate Harvey's failure to emancipate himself from the philosophical encumbrances of antiquity.

The “Scientific Revolution” of the seventeenth century cannot adequately be assessed without an appreciation of the achievements and limitations of those, whether giants or dwarfs, on whose shoulders Galileo and his contemporaries stood. And since for many historians Galileo's main contribution lies in the mathematization of the natural world and especially of time and motion, particular interest attaches to medieval treatises dealing with these questions, above all to those which were in widespread demand early in the sixteenth century.

One of the difficulties with which scientific endeavour is fraught is that of maintaining detachment. The scientist's interest in his work will lead him to formulate hypotheses and the hypotheses will lead him to expectations about future observations. Is disinterested investigation then possible? Surely the very formulation of a hypothesis engenders a paternal affection and a desire to preserve it. Knowing this, however, the scientist is able to guard against his expectations influencing his observations, defending thus both his objectivity and his honour. But in cases where discriminations are exceptionally difficult to make, then here perhaps, in spite of fore-knowledge of the danger, and in spite of all precautions, an expectation may influence a judgement.

Before 1600 the most common method of division used in Europe was the galley, batello, or scratch method, and this was still popular up to the end of the eighteenth century. This method is commonly supposed to be of Hindu origin, being based on a method found in India about the fourth century. It will be shown that the Hindu method is identical to the Chinese method of division (ch'u) mentioned in very early Chinese texts such as the Chiu Chang Suan Shu (Nine Chapters on the Mathematical Art, c. first century a.d.). The earliest detailed description of this method is found in the Sun Tzŭ Suan Ching (The Mathematical Manual of Master Sun, third century a.d.).