2013 marks the 100th anniversary of the publication of Niels Bohr's atomic model which for the first time successfully explained empirically known features of hydrogen line spectra. The results of spectroscopic research on hydrogen of the late 19th and early 20th century have been key elements for the foundation of modern atomic theory. A precondition for the determination spectroscopic series beyond the visible optical domain has been the development of novel experimental and instrumental expertise on the properties of ultraviolet and infrared radiation.

The first line spectrum of hydrogen (n=1 in Rydberg's formula), which today bears the name of its discoverer Theodore Lyman, is entirely located in the ultraviolet domain. Measurements of the UV hydrogen spectrum had been first extended by the retired German engineer and amateur spectroscopist Victor Schumann in Leipzig through improvements in photochemistry and the elimination of UV absorption sources in the optical path.

Schumann's extensive personal and scientific correspondence covered more than 200 hundred scientific experts, instruments makers and editors including William Crookes, Carl Zeiss and Josef Maria Eder. His work however, which was credited by contemporaries including Lyman who refined and extended Schumann's research, is today widely unknown.

Using sources from the archives of the Deutsches Museum and the Bibliotheca Albertina, this paper analyzes Schumann's research as a case study for knowledge transfer in two distinctive dimensions: i) the transcontinental transfer of scientific expertise from Germany to the USA, and ii) the transfer of technology from a self-trained and mostly self-funded individual to the world of academic research.