Market: Scientists, engineers, and graduate students in atomic physics, astrophysics, spectroscopy, atmospheric and solid state physics, and semiconductor research. Drawn from the author's lectures to undergraduates at Oxford University, this 1955 work features probing analyses of many problems in atomic physics, plasma physics, spectroscopy, atmospheric and solid state physics. By emphasizing fundamental concepts and the limitations of treatments rather than the details of theories, this book has become a valued reference tool both in academia and among professionals in the scientific community.