He was the son of the theologianTheodosius Harnack[1] and the twin brother of theologian Adolf von Harnack (who long outlived him) - all of them from Dorpat, now known as Tartu, in the Russian Empire. After his studies at the University of Dorpat (where his father was a professor). In 1873 he moved to Erlangen to become a student of Felix Klein. He published his Ph.D. thesis in 1875 and received the right to teach (venia legendi) at the University of Leipzig the same year. One year later he accepted a position at the Technical University of Darmstadt. In 1877 he married Elisabeth von Öttingen, and they moved to Dresden, where he acquired a professorship in the Polytechnikum, which became a technical university in 1890. Harnack suffered from health problems from 1882 onwards, forcing him to spend long periods in a sanatorium. He published 29 scientific articles and was a well-known mathematician at the time of his death.
Moritz Kassman, Harnack Inequalities: An Introduction Boundary Value Problems (2007), Article ID 81415. (An article on Harnack's inequality that contains a biography of Axel Harnack in the introduction).
