During the course of the eighteenth century important changes occurred in the conception of matter held by British natural philosophers. Historians of science have described these changes in different ways, but certain common features can be abstracted from the more recent accounts. First, there was a movement away from Newtonian matter theory, which saw all matter as the various organizations of homogeneous particles and the forces of attraction and repulsion acting between them. In place of this theory increasing favour was shown towards a more empirical or ‘chemical’ approach to matter which assumed the existence of several essentially distinct types of matter each endowed with different specific qualities or properties. Second, there was an increasing tendency to accept activity as a property of matter itself rather than to ascribe it to immaterial forces.

In spite of vigorous opposition by a number of historians it has now become a commonplace that the rapid development of the ‘new philosophy’ sprang from the ideology of Puritanism. What began its career as the ‘Merton thesis’ has now been refined, developed, and so often repeated that it seems to be almost unassailable. However, the two foremost historians in the entrenchment of this new orthodoxy are willing, in principle, to concede that ‘in reality things were very mixed up’, and that non-Puritan natural philosophers at the time were operating ‘in a precisely similar manner’ to their Puritan contemporaries. Indeed, it would be impossible not to concede this in the face of the many critiques launched against the Merton thesis.

The sciences of ethology and sociobiology have as premisses that certain dispositions and behavioural patterns have evolved with species and, therefore, that the acts of individual animals and men must be viewed in light of innate determinates. These ideas are much older than the now burgeoning disciplines of the biology of behaviour. Their elements were fused in the early constructions of evolutionary theory, and they became integral parts of the developing conception. Historians, however, have usually neglected close examination of the role behaviour has played in the rise of evolutionary thought.

In this paper I want to examine in some detail one eighteenth-century attempt to restructure the foundations of mechanics, that of Leonhard Euler. It is now generally recognized that the idea, due to Mach, that all that happened in the eighteenth century was the elaboration of a deductive and mathematical mechanics on the basis of Newton's Laws is misleading at best. Newton's Principia needed much more than a reformulation in analytic terms if it was to provide the basis for the comprehensive mechanics that was developed in the eighteenth century. Book II of the Principia, in particular, where the problem of the resistance offered to the motion of a finite body by a fluid medium was raised, was generally (and rightly) thought to be in large part mistaken and confused. There were also a number of areas crucial to the unification of mechanics which Newton did not deal with at all in the Principia: particularly the dynamics of rigid, flexible and elastic bodies, and the dynamics of several bodies with mutual interactions. Although a start had been made on some of these topics in the seventeenth century (notably by Galileo, Beeckman, Mersenne, Huygens, Pardies, Hooke, and Leibniz), it was only in the eighteenth century that they were subjected to detailed examination, and Euler's contribution to the development of these topics, and hence to the unification of mechanics, was immense.

Roger Bacon has often been victimized by his friends, who have exaggerated and distorted his place in the history of mathematics. He has too often been viewed as the first, or one of the first, to grasp the possibilities and promote the cause of modern mathematical physics. Even those who have noticed that Bacon was more given to the praise than to the practice of mathematics have seen in his programmatic statements an anticipation of seventeenth-century achievements. But if we judge Bacon by twentieth-century criteria and pronounce him an anticipator of modern science, we will fail totally to understand his true contributions; for Bacon was not looking to the future, but responding to the past; he was grappling with ancient traditions and attempting to apply the truth thus gained to the needs of thirteenth-century Christendom. If we wish to understand Bacon, therefore, we must take a backward, rather than a forward, look; we must view him in relation to his predecessors and contemporaries rather than his successors; we must consider not his influence, but his sources and the use to which he put them.

Every science has its technical vocabulary, consisting in part of terms coined for explicit purposes and in part of words borrowed from ordinary discourse and used with greater or lesser degrees of precision. Words of the latter sort pose curious problems, some of them familiar to those historians of science concerned with, for example, what Galileo meant by forza and Newton by attraction. Indeed, analogous problems face any historian seeking to understand the older meanings of terms still in use today.

Science historians need two major kinds of literary resources, old books, journals, patents, plans and other documents from which to quarry their facts, and critical tools such as histories of science, bibliographies and biographies. Provision of the second category needs positive planning; the first is often itself an accident of local history. Among the factors which have shaped Newcastle upon Tyne may be numbered a Roman river crossing, a Norman castle, mediaeval walls, powerful charters granted by Tudor and Stuart monarchs, a favourable site in a coalfield, and a phenomenal succession of inventive entrepreneurs in mining, chemicals, shipbuilding, and mechanical and electrical engineering. Its scientific and cultural institutions (see Table) are of respectable maturity, and in addition the town possessed by 1815 several chapel and meeting-house libraries, a newsroom and subscription library in the Assembly Rooms together with three circulating libraries run by prominent booksellers. Present resources are concentrated in six organizations, with two more in the near future.

In 1859 Charles Darwin in chapter nine of the Origin of Species showed how he had calculated that the age of the Weald was three hundred million years and that consequently the age of the earth was considerably greater than that. Darwin of course needed such a long period of time for the process of evolution by natural selection to occur. Arguments which showed that the earth could not be that old would therefore cast serious doubt on his theory. Such views were advanced in 1862 by William Thomson, later Lord Kelvin, professor of Natural Philosophy at Glasgow. He specifically challenged the result of Darwin's calculation of the age of the Weald by arguing that the sun could not have emitted its heat and light for that length of time. The consequences of this assertion for the biological and geological sciences for the remainder of the nineteenth century have already been delineated by Burchfield. What I wish to do in this paper is to show that the theoretical basis of Thomson's 1862 assertion had not been specifically developed as a response to Darwin, but that it was a consequence of the formulation of the first two laws of thermodynamics. I shall also show that Thomson's work was not done in isolation but that the question of the maintenance of solar energy was a serious concern of a number of physicists who had formulated the laws of thermodynamics.

When Charles Darwin published his theory in 1859 the biological community gave very different receptions to the idea of evolution and to the theory of natural selection. Evolution was accepted as widely and rapidly as natural selection was rejected. Most biologists were ready to accept that evolution had occurred, but not that natural selection was its cause. They preferred other explanations of evolution, such as theories of big directed variation, or admitted that they did not know its cause. Darwin himself never maintained that natural selection was the sole cause of evolution. He thought of it as one among several causes, and did not specify how much evolution had occurred by the natural selection of fortuitous variations, and how much by other factors such as the inherited effects of use and disuse. However, Darwin did maintain that natural selection was in principle capable of explaining all the observed properties of organisms. He did not think that there were some characteristics that were particularly likely to have evolved by natural selection, and other kinds that were not. Against this, many of this critics thought that there were characteristics that natural selection was particularly powerless to explain. Thus it could not account for characteristics that were detrimental, or those that seemed useless (such as species differences), or those that were of too little importance for natural selection to have favoured them. There were also characteristics of such complexity that it was unimaginable that natural selection could have built them up in tiny stages from fortuitous, undirected variants. The present essay will be concerned with just one, the last mentioned, of these kinds of characteristics.