The years immediately after the final downfall of Napoleon Bonaparte could easily have been years of anti-climax in French science. In 1815, after two decades of undoubted greatness, the time, I feel, was ripe for decline. And decline might well have occurred if the traditions and the style of science as practised in France in the period of Napoleon's rule had been carried on unchanged by the disciples of the two great men who had dominated work in the physical sciences for so many years. These men, of course, were the chemist Claude Louis Berthollet and the mathematician and physicist Pierre Simon Laplace.

Attempts in antiquity and the Middle Ages to determine the mathematical law of refraction are well known. In view of the movement toward the mathematization of physical laws, which has made great gains since the beginning of the seventeenth century, and of the efforts of Hariot, Kepler, Snell, and Descartes to determine the true mathematical ratio between the angles of incidence and refraction, it is understandable that historians of pre-seventeenth-century science should concentrate on the quantitative aspects of refraction. But to do so is to gain a distorted picture of early optical thought, for as much effort was actually devoted to understanding the cause of refraction as to finding the mathematical law of refraction.

Most modern analysts of Newton's laws of motion, whether they have approached the subject from a historical or from a philosophical viewpoint, have tended to concentrate on the status of the first two laws; the third law has largely been overlooked, or else it has been dismissed as somehow less interesting. My purpose in this paper is to reverse this approach—I intend to investigate some of the historical aspects of the third law, particularly the empirical background to Newton's statement of it, and in so doing, I intend to skirt most of the questions which have been raised concerning the status of the other two laws. In concentrating on the historical aspects of the third law, I shall also by-pass Mach's controversial re-interpretation of its role in mechanics, for while Mach saw the law as the basis for an operational definition of “mass”, it is quite clear that Newton did not so regard it. On the contrary, Newton seems to have regarded all three of his laws as straightforward statements of fact about the world, so that a knowledge of the factual background to the laws is a fundamental pre-requisite to an understanding of Newton's thought.

Shortly before his death in 1934, the British historian of chemistry, A. N. Meldrum, published two lengthy articles on Lavoisier's early career in science. After a careful investigation of the collection of manuscripts at the Académie des Sciences in Paris and in light of a detailed and penetrating analysis of Lavoisier's published work, Meldrum concluded that as a youth, Lavoisier was concerned with chemistry only to the extent that he found it useful for his mineralogical and geological researches. Lavoisier began his career as a mineralogist; he became a chemist only in 1772, the “crucial year” when he turned his attention to chemical theory for its own sake and started his famous course of experiments on the nature of combustion and fixed air. Although some details—notably concerning Lavoisier's early education and geological work—have been added to this account since Meldrum's time, the broad conclusions of Meldrum's study are still generally accepted by historians of the chemical revolution.

Charles Babbage's Reflections on the Decline of Science in England … is very well known to historians of science who are aware of its role in the movement to found the British Association for the Advancement of Science and to reform the Royal Society. The work is probably responsible, in large measure, for the assumption that science in Great Britain was in a marked decline in the early decades of the last century, an assumption rarely subject to exact analysis although fairly widely held. Not as widely known is a reply to Babbage written by Gerard Moll of Utrecht and presented to the English reading public by Faraday, one of the men attacked in Babbage's volume. To the best of my knowledge, Babbage's only published rejoinder to Moll appeared in 1851, dismissing Moll and other critics as not having challenged his facts.

The rise of stereochemistry in the 1880s stimulated a few organic chemists to speculate about the complexity of atoms.