SUCCEEDING HIMSELF IN 1902 to the Chair of Theoretical Physics at the University of Vienna, Ludwig Boltzmann emphasized in his Inaugural Address that "mechanics is the foundation on which the whole edifice of theoretical physics is built, the root from which all other branches of science spring" (1902). The goal of a mechanical interpretation of nature, that is, a mechanical world-picture,¹ had been a central theme throughout Boltzmann's researches in statistical mechanics² and electromagnetism. But, owing to recent developments in electromagnetic theory, Boltzmann had begun to qualify this hope somewhat. For diametrically opposite to the mechanical world-picture was the program that Wilhelm Wien had referred to in 1900 as the electromagnetic world-picture, whose goal was to deduce mechanics from electromagnetism.³ In 1904 Boltzmann's desire for unification of the sciences led him to endorse that program.