Editing Felix Hausdorff (section)

===Degree, doctorate and Habilitation===

From 1887 to 1891 Hausdorff studied [[mathematics]] and [[astronom]]y, mainly in his native city of Leipzig, interrupted by one semester in [[Freiburg]] (summer 1888) and [[Berlin]] (winter 1888/1889). Surviving testimony from other students depict him as an extremely versatile and interested young man, who, in addition to the mathematical and astronomical lectures, attended lectures in [[physics]], [[chemistry]] and [[geography]], and also lectures on [[philosophy]] and [[history of philosophy]], as well as on issues of [[linguistics|language]], [[literature]] and [[social sciences]]. In Leipzig he attended lectures on the [[history of music]] from musicologist [[Oscar Paul]]. His early love of music lasted a lifetime; in Hausdorff's home he held impressive musical evenings with the landlord at the piano, according to witness statements made by various participants. Even as a student in Leipzig, he was an admirer and connoisseur of the music of [[Richard Wagner]].

In later semesters of his studies, Hausdorff was close to [[Heinrich Bruns]] (1848–1919). 
Bruns was professor of astronomy and director of the observatory at the University of Leipzig. Under his supervision, Hausdorff graduated in 1891 with a work on the theory of astronomical refraction of light in the atmosphere. Two publications on the same subject followed, and in 1895 his [[Habilitation]] also followed with a thesis on the absorbance of light in the atmosphere. These early astronomical works of Hausdorff, despite their excellent mathematical formulation, were ultimately of little importance to the scientific community.
For one, the underlying idea of Bruns was later shown to not be viable (there was a need for refraction observations near the astronomical horizon, and as Julius Bauschinger would show, this could not be obtained with the required accuracy). And further, the progress in the direct measurement of atmospheric data (from [[weather balloon]] ascents) has since made the painstaking accuracy of this data from refraction observations unnecessary. In the time between defending his PhD and his Habilitation, Hausdorff completed his yearlong military requirement, and worked for two years as a [[human computer]] at the [[observatory]] in Leipzig.