Students, teachers, and researchers in physical optics, astrophysics, optometry, film optics, and related fields will welcome this unabridged reprint of one of the finest fundamental texts in physical optics. A classic study, The Theory of Optics remains unsurpassed for its wide, thorough coverage and its complete mathematical treatment of fundamentals. One of the first applications of Maxwell's electromagnetic theory as developed by Hertz to the problem of light, it offers copious valuable material unavailable elsewhere in a single volume--including one of the fullest treatments of the application of thermodynamics to optics. Powerful and significant in its approach, it explains the important practical and theoretical consequences that may be deduced simply and directly from elementary principles. Areas of investigation include temperature radiation and luminescence, Kirchoff's law of emission and absorption, the sine law in the formation of images of surface elements, the effect of change of temperature on the spectrum of a black body, and the distribution of energy in the spectrum of such a body. Additional topics include absorbing media, crystal optics, and interference.