The Austrian physicist Ludwig Eduard Boltzmann (1844–1906), educated at the University of Vienna, was appointed professor of mathematical physics at the University of Graz in 1869 at the age of only twenty-five. Boltzmann did important work in the fields of statistical mechanics and statistical thermodynamics; for instance, he contributed to the kinetic theory concerned with molecular speeds in gas. Boltzmann also promoted atomic theory, which at the time was still highly controversial. He was a member of the Imperial Austrian Academy of Sciences from 1885 and became a member of the Royal Swedish Academy of Sciences in 1888. This three-volume work, prepared in 1909 by the physicist Fritz Hasenöhrl, one of Boltzmann's students, comprises all his academic publications from 1865 to 1905.