Biography - Dame Kathleen Lonsdale (1903 - 1971)

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How do we know that the benzene ring is flat? Because in 1929 Kathleen Lonsdale determined that the arrangement of the carbon atoms in hexamethylbenzene is hexagonal. (Read the article here.) As she comments, this was “definite proof, from an X-ray point of view,” that the six-membered ring in aromatic compounds is planar. This was the first time that the atomic positions were found without any prior assumptions about the molecule. It is interesting to read her publication today and appreciate her methods, before “direct methods” enabled crystallographers to solve a light-atom structure like this one, and before the tabulation of temperature factors and atomic scattering factors in International Tables for X-ray Crystallography.

One of Lonsdale’s contributions to the crystallographic community was her 1936 book Simplified Structure Factor and Electron Density Formulae for the 230 Space Groups of Mathematical Crystallography. It was completely handwritten! See a sample page for a tetragonal space group here.

Kathleen Lonsdale  ca. 1935. (Copyright The Royal Society)

Lonsdale served on the international committee that supervised the publication in 1935 of the Internationale Tabellen zur Bestimmung von Kristallstrukturen. This two-volume work standardized the space group notation and symmetry-related positions for the space groups. From 1946 onward she was deeply involved in the planning for the subsequent International Tables for X-ray Crystallography published by IUCr. She and N. M. F. Henry edited volume one, Symmetry Groups (1952); she and J. S. Kasper edited volume two, Mathematical Tables (1959. (See more detailed information about the publications of the IUCr and the early history of International Tables here.)

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Left to right, standing: Martin Buerger, Harold Wyckoff, and Dame Kathleen Lonsdale lecturing to a class. (AIP Emilio Segrè Visual Archives, Fankuchen Collection)

See more about Kathleen Lonsdale’s life and career here.