Leiden University at the university. The learning and reputation of Jacobus Gronovius, Herman Boerhaave, Tiberius Hemsterhuis and David Ruhnken, among others, enabled Leiden to maintain its reputation for excellence down to the end of the 18th century. At the end of the nineteenth century, Leiden University again became one of Europe's leading universities. At the world’s first university low-temperature laboratory, professor Heike Kamerlingh Onnes achieved temperatures of only one degree above absolute zero of −273 degrees Celsius. In 1908 he was also the first to succeed in liquifying helium and can be credited with the discovery of the superconductivity in metals. The
Harm Kamerlingh Onnes Lorentz as a subject. One of these stained-glass windows contained a portrait of Hendrik Lorentz and formulas devised by him that describe the behavior of electrons. Other stained-glass windows show the instruments to measure the splitting of spectral lines of atoms under the influence of a magnetic field is measured, the so-called Zeeman effect. He also made portraits of the physicists Albert Einstein and Paul Ehrenfest. Harm Kamerlingh Onnes characterized his artistic work with the phrase "just messing around". In 1953 Kamerlingh Onnes with Bert Nienhuis Piet Wiegman, Dirk Hubers and Frans Wildenhain, took part of the exhibition "five contemporary