D O C U M E N T 5 2 F E B R U A R Y 1 9 2 2 1 3 9 in recognition of scientific achievements or contributions to the promotion of science. For details, see Grau 1992. Wilhelm Haensch was a partner in the firm Franz Schmidt & Haensch, which produced high- precision instruments. Einstein read the proposal the following day during the session of the physical- mathematical class of the Prussian Academy of Sciences (Kirsten and Treder 1979b, p. 247, No. 240). Eugen H. Brodhun (1860–1938) was a physicist at the PTR. The proposal for Niels Bohr’s foreign corresponding membership was submitted to the mathe- matical-physical class the same day (see Doc. 53). Heike Kamerlingh Onnes was officially elected foreign correspondent during the session of 16 February 1922 (GyPAW [1812–1945] II-V-135). For his paper published in French in the Commu- nications, see Timmermans et al. 1922. Kamerlingh Onnes 1921. The Solvay Institute of Physics in Brussels was founded in 1912 by the Belgian industrialist Ernest Solvay (1838–1922). Heike Kamerlingh Onnes was a member of its administrative committee.