The field of particle physics is developing very rapidly. During this past year, physicists added a new instrument to their arsenal for the study of quark-quark, quark-lepton, and lepton lepton interactions. This machine, the PROTON-ANTIPROTON COLLIDER, achieved the highest energy in the world. With its five detectors, it is beginning to explore hitherto inaccessible regions for new physics (Section I). Lepton-Iepto~ machines with detectors at full efficiency are producing copious data of the very highest precision. The possibility of glueballs and the detailing of the properties of the upsilon family have been of major importance this year (Section II). The particle jets which are believed to be direct manifesta tions of the quark structure of matter continue to provide valuable data against which we can test the ideas of QCD (Section III). With the advent of more and better data it is now possible to study in detail the formation evolution of hadronic states. Especially interesting are the properties of heavy quark states (Section IV). A far-seeing look into the future development of any fecund scienti fic field is rarely accurate, but is always stimulating (Section V). It is against this background of participating in the clarifi cation of the Physics in Collision that we continue this series.

Widely regarded as a classic in its field, Constructing Quarks recounts the history of the post-war conceptual development of elementary-particle physics. Inviting a reappraisal of the status of scientific knowledge, Andrew Pickering suggests that scientists are not mere passive observers and reporters of nature. Rather they are social beings as well as active constructors of natural phenomena who engage in both experimental and theoretical practice. "A prodigious piece of scholarship that I can heartily recommend."—Michael Riordan, New Scientist "An admirable history. . . . Detailed and so accurate."—Hugh N. Pendleton, Physics Today

Translated by Alex Levine The nineteenth century was a formative period for electromagnetism and electrodynamics. Hans Christian Orsted's groundbreaking discovery of the interaction between electricity and magnetism in 1820 inspired a wave of research, led to the science of electrodynamics, and resulted in the development of electromagnetic theory. Remarkably, in response, Andre-Marie Ampere and Michael Faraday developed two incompatible, competing theories. Although their approaches and conceptual frameworks were fundamentally different, together their work launched a technological revolution—laying the foundation for our modern scientific understanding of electricity—and one of the most important debates in physics, between electrodynamic action-at-a-distance and field theories. In this foundational study, Friedrich Steinle compares the influential work of Ampere and Faraday to reveal the prominent role of exploratory experimentation in the development of science. While this exploratory phase was responsible for decisive conceptual innovations, it has yet to be examined in such great detail. Focusing on Ampere's and Faraday's research practices, reconstructed from previously unknown archival materials, including laboratory notes, diaries, letters, and interactions with instrument makers, this book considers both the historic and epistemological basis of exploratory experimentation and its importance to scientific development.