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 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 Rigorosumoral examination to complete his doctorate.
Technical optics: Carl Zeiss in Jena (1884 onwards)
His interest in physical and technical optics enabled him to gain a position at Carl Bamberg's workshop for scientific precision instruments. Abbe involved Czapski in his theoretical studies as early as 1885. It was Czapski who went on to publish these studies the following year because Abbe himself had neither the time nor the patience, being too occupied with his development projects. In 1893, after five years of work, Czapski finally completed his contribution to Adolf Winkelmann's Handbuch der Physik entitled Theorie der optischen Instrumente nach Abbe. The 300-page work was issued that very same year as a separate publication from volume II of the encyclopedia and was hailed as a key work inthe field of technical optics. Working with Abbe and Otto Schott in Jena and with Leopold Dippel in Darmstadt, Czapski was involved in the design and fabrication of new microscope optical systems from the moment he started work in Jena. He subsequently worked on the technical implementation of a binocular microscope based on ideas put forward by the American biologist Horatio S. Greenough. As the company expanded, so too did its range of products: Zeiss started producing photographic objectives in 1890, optical measuring instruments in 1892/93, prism binoculars in 1893/94, astronomical instruments in 1897 and image measuring devices in 1901. Czapski steadily took on more and more responsibility as Zeiss increased its product portfolio and workforce and as its fame spread far beyond the borders of Germany. In 1891 he became one of the company's three managing directors.
Establishment of the Carl-Zeiss-Stiftung
Founded in 1889 by Abbe, the Carl-Zeiss-Stiftung took the entire Zeiss company and half of the Schott company under its wing in 1891. Czapski was subsequently appointed as an authorized representative of the Foundation. Working closely with Abbe and a foundation inspector from the Grand-Ducal Saxon State Ministry in Weimar, Czapski played an ever greater role in managing the company, something that took an increasing toll on his health. Abbe already had the university trustee Heinrich Eggeling and the lawyer Eduard Rosenthal involved in drawing up the Foundation statutes and he soon included Czapski in that task – even though by this point Czapski was increasingly overwhelmed by concerns and problems relating to the workforce. Work on the statutes was completed in 1895/96.
Siegfried and Margarete Czapski
In 1885 Czapski's life changed dramatically when he met and fell in love with Margarete Koch. Margarete was the granddaughter of Abbe's teacher, the mathematician and physicistKarl Snell. Margarete's father was a professor at a grammar school in Paris and a nephew of Juliette Drouet, who was Victor Hugo's partner for much of his life. His wife Ottilie Koch often brought their daughter to visit her father in Jena. Ottilie was also the sister of Abbe's wife, Else Abbe. It was inevitable that 24-year-old Czapski and 19-year-old Margarete Koch would eventually meet. Just weeks after getting to know each other they got engaged, secretly at first. They agreed that they would marry when Margarete turned 21. The wedding took place on August 11, 1887. Their marriage produced eight children:
Czapski had long been suffering from ill health, and his huge workload made the situation even more difficult. On June 29 he died of a pulmonary embolism due to complications after an appendectomy. Having been the close working companion of his friend and mentor Ernst Abbe, and ultimately his successor, Czapski was only destined to outlive Abbe by a mere two-and-a-half years.
Honor
A street in Jena, near the Carl Zeiss works, is named after him: Siegfried-Czapski-Straße, a few blocks off Zeiss Promenade.
Publications
His most important publication was Theorie der optischen Instrumente, nach Abbe.
