Siegfried Czapski (28 May 1861 – 29 June 1907) was a German physicist and optician. Childhood, school and university in Breslau (1870–1881) Czapski was the son of Simon Czapski (1826–1908) and his wife Rosalie Goldenring (1830-1916) on the Obra estate near Koschmin in the Province of Posen. His family was Jewish, and he was related to the physician Albert Neisser. In 1870 Czapski's father suffered a serious accident which left him unable to work. The family sold their estate and moved to Breslau (Wrocław) where, in 1872, eleven-year-old Czapski began attending school at the Maria Magdalenen Gymnasium. In 1879 he completed his university entrance examination (together with Wilhelm Prausnitz, Richard Reitzenstein and Felix Skutsch) and spent a semester studying at the University of Göttingen, attending lectures by Eduard Riecke (physics), Moritz Abraham Stern (mathematics) and Rudolf Hermann Lotze (philosophy). At the start of his second semester he switched to the University of Breslau, studying physics under Oskar Emil Meyer, Ernst Dorn and Felix Auerbach, mathematics under Jakob Rosanes and philosophy under Jacob Freudenthal. It was during this period that he embarked on a friendship with Arthur Heidenhain (1862–1941) which led to a lifelong exchange of letters. University and doctorate in Berlin (1881–1884) In 1881 Czapski switched to the University of Berlin to study under the physicists Hermann von Helmholtz and Gustav Robert Kirchhoff. Here he met Leopold Loewenherz and became interested in experimental physics, which prompted him to start attending more practical, hands-on courses. In 1882 Czapski began work for the Normal-Eichungskommission (Imperial Institute for Weights and Measures) which was headed by the astronomer Wilhelm Julius Foerster. In the autumn of that year he worked on his doctorate under the supervision of Hermann von Helmholtz, in which he conducted experiments to investigate one of Helmholtz's own theories. He submitted his doctoral thesis to Helmholtz and Kirchhoff in November 1883. In December he embarked on his doctoral exams which were held by Helmholtz and Kirchhoff in physics, Leopold Kronecker in mathematics and Eduard Zeller in philosophy. In February 1884 he took his Rigorosum oral examination (doctoral viva) to complete his doctorate. Technical optics: Carl Zeiss in Jena (1884 onwards) His interest in physical and technical optics (the design and fabrication of optics) enabled him to gain a position at Carl Bamberg's workshop for scientific precision instruments (subsequently known as the Askania works). Keen to explore these areas in more depth, he