Tegen de roof: het Kamerlingh Onnes Laboratorium in oorlogstijd

Abstract

Against the Robbery: The Kamerlingh Onnes Laboratory in the Second World War The Kamerlingh Onnes Laboratory, home to Leiden University's physics programme, continued its work during the war years, even though the university closed in the autumn of 1940. The main argument for keeping it open was to prevent robbery of the instruments by the Germans. To this reason, laboratory director Wander Johannes de Haas stressed the unique character of the Leiden school for instrument-makers, which had merged completely with the laboratory. Unequalled in the Netherlands (and elsewhere), this school trained craftsmen who were in high demand on the labour market. On the initiative of de Haas, in 1942 the Kamerlingh Onnes Laboratory was placed under the auspices of Delft Technical University. The other director, Willem Keesom, was absent for health reasons for almost the duration of the war. In the pre-war period, De Haas had taken the remarkable step of purchasing a large stock of uranium. During the war, he and the doctoral candidate Jacob Kistemaker were paid to perform services for the German intelligence service Cellastic, based in Paris. After the liberation of the Netherlands, De Haas was briefly suspended for these activities, but was never convicted. The cryogenic research taking place in Leiden continued more or less unabated until the spring of 1944, when some of the laboratory's equipment was requisitioned and taken away by the German occupiers. Activities for the Dutch resistance also took place at the laboratory.