I -- Testing Theories of Scientific Change -- II: Case Studies -- 1. 17Th-Century Mechanics -- Galileo’s Copernicanism and the Acceptability of Guiding Assumptions -- Newton’s Rejection of the Mechanical AEther: Empirical Difficulties and Guiding Assumptions -- The Vortex Theory of Motion, 1687–1713: Empirical Difficulties and Guiding Assumptions -- 2. Chemistry from the 18th to the 20th Centuries -- The Chemical Revolution: Shifts in Guiding Assumptions -- Molecular Geometry in 19th-century France: Shifts in Guiding Assumptions -- Kekulé’s Benzene Theory and the Appraisal of Scientific Theories -- Fermentation Theory: Empirical Difficulties and Guiding Assumptions -- The Polywater Episode and the Appraisal of Theories -- 3. 19Th-Century Physics -- Ampère’s Electrodynamics and the Acceptability of Guiding Assumptions -- Brownian Motion and the Appraisal of Theories -- The Michelson — Morley Experiment and the Appraisal of Theories -- 4. Recent Geological Theory -- Plate Tectonics and Inter-Theory Relations -- The Theory of an Expanding Earth and the Acceptability of Guiding Assumptions -- 5. 20th-Century Physics -- Planck’s Quantum Crisis and Shifts in Guiding Assumptions -- Nuclear Magnetic Resonance and the Acceptability of Guiding Assumptions -- Electroweak Unification and the Appraisal of Theories -- Index of Thesis Citations and.