John A. Schuster
This article examines the physics of René Descartes. Descartes’ natural philosophy marks a significant moment in the larger history of physics. His system of natural philosophy was a novel, daring, and intricate construction in that field, with two main sets of historical significances for later physics. Before discussing these two significant consequences of Descartes’ natural philosophy for physics, the article provides an overview of the developmental anatomy of Cartesian physics during the period 1618–1644. In particular, it considers the successes, failures, and fate of Descartes’ early physico-mathematics programme, his work on physico-mathematical optics and corpuscular dynamics, and his career inflection between 1628 and 1633. It also explores Descartes’ ideas on vortex celestial mechanics, the explanatory style of mature Cartesian physics, and his work on classical mechanics. Finally, it looks at Descartes’ concerns with realist Copernicanism.
Jed Z. Buchwald
This article focuses on developments in electricity and magnetism up to the time of Alessandro Volta. Until the late 1600s electricity as a subject reduced to what has been aptly termed the ‘amber effect’. At the beginning of the century William Gilbert broadened the class of objects that could produce the effect and at the same time introduced a fundamental distinction between it and the properties of the lodestone, or magnet. Gilbert’s Scholastic understanding of magnetism contrasts markedly with what seems to be a quasi-mechanical understanding of electricity, the latter being more congenial to the post-Scholastic way of thinking about nature. This article first provides an overview of experiments on electric objects, including the Leiden jar, before discussing Volta’s quantification of the distinction between amount of electricity and electric tension around 1780.
Jed Z. Buchwald
This article examines developments in the field of electrodynamics from William Thomson and James Clerk Maxwell to Heinrich Hertz. It begins with a discussion of Michael Faraday’s work, focusing on his discovery of what was later termed ‘dielectric capacity’ and his role in the birth of field theory. It then considers Thomson’s unification of Faraday’s understanding of both electro- and magnetostatics with energy conservation, along with Maxwell’s extension of Thomson’s structure to cover electrodynamics, which for the first time brought to the fore issues concerning the electric current. It also describes Maxwellian electrodynamics and electromagnetic theory, Hermann Helmholtz’s development of a different form of electrodynamics, and Hertz’s work on electric waves.
This article examines developments in electromagnetism and field physics during the early nineteenth century, when electricity had become a fully respected area of research. It begins with a discussion of the ‘Volta’s pile’, an apparatus developed by Alessandro Volta, along with mathematical approaches to electricity and Hans-Christian Ørsted’s discovery of electromagnetism. It then reviews the work of André-Marie Ampère and the Biot–Savart law, introduced by Jean Baptiste Biot and Félix Savart; developments in electrodynamics during the period 1821–1826; and Michael Faraday’s research initiative in electromagnetism, and especially electromagnetic induction and the electrotonic state. It also looks at three important developments in electromagnetism during the 1820s: galvanometers, electromagnets, and Arago’s effect. Finally, it describes Lenz’s law, electromagnetic generators, the electromagnetic telegraph, the Faraday effect, diamagnetism, and the question of polarity as well as the role of mathematics in Faraday’s theories.
Olivier Darrigol and Jürgen Renn
This article traces the history of statistical mechanics, beginning with a discussion of mechanical models of thermal phenomena. In particular, it considers how several circumstances, including the establishment of thermodynamics in the mid-nineteenth century, led to a focus on the model of heat as a motion of particles. It then describes the concept of heat as fluid and the kinetic theory before turning to gas theory and how it served as a bridge between mechanics and thermodynamics. It also explores gases as particles in motion, the Maxwell–Boltzmann distribution, the problem of specific heats, challenges to the second law of thermodynamics, and the probabilistic interpretation of entropy. Finally, it examines how the results of the kinetic theory assumed a new meaning as cornerstones of a more broadly conceived statistical physics, along with Josiah Willard Gibbs and Albert Einstein’s development of statistical mechanics as a synthetic framework.
This article focuses on the construction of the new sciences of thermodynamics and energy in Britain during the Victorian era, arguing that it occurred not simply within the broad contexts of industrialized engineering but that the new industries of marine engineering and the new sciences were, in specific local contexts on the Thames and on the Clyde, integral to one another. It begins with an account of James Thomson’s marine engineering networks centred on the Thames at Millwall, followed by a discussion on the work of his brother William at the Glasgow College laboratory. It then considers Robert Mansel’s development of an exceptionally sensitive thermometer before turning to the shipbuilding yards and marine engineering works of the Clyde at Glasgow, still in its relative infancy as the producer of the British Empire’s ocean steamers.
Domenico Bertoloni Meli
This article examines experimentation in the physical sciences during the seventeenth century. It first provides an overview of some features and problems of seventeenth-century experimentation before discussing experiments on the science of motion, with particular emphasis on falling bodies, the inclined plane and projectiles, and the pendulum. It then considers barometric experiments associated with Torricelli and their aftermath, including Florin Périer’s Puy-de Dôme experiment in 1648 to test whether the mercury in the barometer was lower at the top, Adrien Auzout’s void-in-the-void experiment, and Gilles de Roberval’s carp-bladder experiment. It also describes the experiments of Otto von Guericke and Robert Boyle, along with optical experiments designed to investigate the behaviour and nature of light, including Isaac Newton’s prismatic experiments.
This article focuses on the evolution and transformations of the instrument-making industry between 1850 and 1930. It begins with an overview of some broad categories of instruments, namely: research and precision measurement instruments, didactic and teaching instruments, industrial instruments, professional instruments, and scientific instruments. It then examines the history of the production of physics instruments and how workshops were organized, along with some of the techniques and materials used in the production of instruments. It also discusses the advertising, trading, and selling of instruments during the period; how instrument-makers in France, Britain, and Germany fared; the state of instrument-making from 1900 to World War I; and instrument-making in the United States and other countries in Europe. Finally, it evaluates instrument-making during the inter-war years.
N. M. Swerdlow
This article examines Galileo’s ideas about the mechanics of natural motion and projectiles. Among the subjects in mechanics considered by Galileo, the most important are ‘natural motion’, the descent of falling bodies including on inclined planes, and the motion of projectiles under an impressed force. He also considered, and made contributions to, the resistance of solid bodies to fracture and the hydrostatics of floating bodies. What is often called ‘Platonism’ in Galileo, his appeal to mathematics and idealized conditions, is in fact the abstract mathematical analysis of mechanics. This article considers Galileo’s research and writing on falling bodies and projectiles, including his early treatise De motu, the Dialogue on the Two Great Systems of the World, the manuscript Firenze Biblioteca Nazionale Centrale Galileo Ms. 72, and the Discourses and Mathematical Demonstrations concerning Two New Sciences.
This article focuses on instruments and instrument-makers during the period 1700–1850. Scientific instruments in the 150 years between 1700 and 1850 enjoyed rapid advances in design and technology that the period can usefully be divided at about 1800, though the date varied with the progress or otherwise in the lands concerned. Throughout this period the leading craftsmen were becoming better-educated, many having a good grasp of mathematics. This article deals mainly with instruments and their makers in Britain, with a brief survey of the situation in western Europe and in the United States. It first describes the political situation in Europe before discussing the British instrument-makers’ workshop practice and materials available in the craftsmen’s workshops, including brass and other alloys, glass and wood. It also considers the British market for optical instruments and philosophical instruments, along with instrument-makers and markets in Continental Europe and the United States.