These remarks preface two volumes consisting of the proceedings of the Third International Conference on the History and Philosophy of Science of the International Union of History and Philosophy of Science. The conference was held under the auspices of the Union, The Social Sciences and Humanities Research Council of Canada, and the Canadian Society for History and Philosophy of Science. The meetings took place in Montreal, Canada, 25--29 August 1980, with Concordia University as host institution. The program of the conference was arranged by a Joint Commission of the International Union of...

and less as the emanation unden'ent radioactive decay, and it became motion- less after about 30 seconds. Since this process was occurring very rapidly, Hahn and Sackur marked the position of the pointer on a scale with pencil marks. As a timing device they used a metronome that beat out intervals of approximately 1. 3 seconds. This simple method enabled them to determine that the half-life of the emanations of actinium and emanium were the same. Although Giesel's measurements had been more precise than Debierne's, the name of actinium was retained since Debierne had made the discovery first....

This collection of essays is a tribute to Stillman Drake by some of his friends and colleagues, and by others on whom his work has had a formative influence. It is difficult to know him without succumbing to his combination of discipline and enthusiasm, even in fields remote from Renaissance physics and natural philosophy; and so he should not be surprised in this volume to see emphases and methods congenial to him, even on topics as remote as Darwin or the chemical revolution. Therein lies whatever unity the discerning reader may find in this book, beyond the natural focus and coherence of...