Crystal Clear

By Christy Martin | April 12, 2012

British physicist Sir William Lawrence Bragg had nothing but great things to say about his father’s former student, collaborator, and friend Dame Kathleen Lonsdale. “She was one of the most thorough, high-principled, and courageous people I have known. We who work in the field of X-ray analysis cannot be too grateful for all she did to help us.” He was not alone in his admiration, as shown by the legacy this pioneering female scientist left behind.

Born on January 28, 1903, Lonsdale (nee Yardley) was the youngest of 10 children in a poor Irish family that moved to England when she was five. During her school years she won scholarships and excelled in many subjects, especially mathematics and science, which she learned at a boys’ school. (Lonsdale’s Woodford County High School for Girls offered little instruction in those areas.) After winning another scholarship at age 16, Lonsdale decided to study mathematics at Bedford College for Women in London.

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Kathleen Lonsdale.

Science and Society Picture Library

Lonsdale switched from math to physics against the wishes of her old headmistress, who believed her brilliant student would have little chance of distinguishing herself in that discipline. Yet Lonsdale finished her B.Sc. honors degree with the highest exam marks handed out by examiners not only for that year but for the previous 10 years. This achievement caught the attention of a certain William Henry Bragg, one of the examiners and a Nobel laureate (for his work in X-ray diffraction). Bragg offered her a position on his research team at University College London, which she gladly accepted. He advised Lonsdale to study organic crystal structures and mathematical crystallography and then left her entirely free to follow her own line of research.

While at the college she met an engineering student named Thomas Lonsdale, and in 1927 the two married. They moved to Leeds, in northern England, where Thomas had a job as an assistant at the university. For a brief moment Lonsdale thought about giving up research to become a housewife and mother, but Thomas refused, saying he did not marry her to provide himself with a free housekeeper. Instead the couple went grocery shopping together, and Lonsdale made quick meals that took no longer than 30 minutes to prepare.

With her husband’s encouragement Lonsdale continued her X-ray diffraction work in the Department of Physics at the University of Leeds. C. K. Ingold, a chemistry professor at the university, gave her crystals of hexamethylbenzene. In 1928 Lonsdale definitively put an end to a 60-year debate about benzene and its ring structure; through experimentation and calculation she showed that the benzene ring is flat, and she defined approximately its dimensions.

The following year she had her first child; two more quickly followed. Lonsdale spent much of her time at home with them, where she also continued with her crystal-structure calculations. Lonsdale was a minority within a minority; there were few female scientists, and even fewer were married with children. Nonetheless, she became one of the first women to be elected to the Royal Society and later became the first woman to hold the presidency of the British Association for the Advancement of Science.

Lonsdale’s legacy is marked with one additional item alongside quotes of praise and lists of former titles: she also has the distinction of being the namesake for lonsdaleite, a kind of diamond found in meteorites. It’s a fitting tribute to a woman renowned for her strength and substance.

Kathleen Lonsdale attends Bedford College for Women in London on a science scholarship and studies physics. After graduation she works with Nobel laureate William Henry Bragg.

While at the University of Leeds with her husband, Thomas, Lonsdale determines the dimensions of the benzene molecule.

Lonsdale, returned to London, joins Bragg’s laboratory and studies crystal structure through the analysis of X-ray diffraction patterns.

Lonsdale, a committed pacifist, refuses to register for wartime duties and protests the resulting two-pound fine. The government sentences her to one month in jail.

The Royal Society admits Lonsdale as a fellow. She and Marjorie Stephenson are the first women accorded this honor.

Lonsdale is appointed reader of crystallography at University College London and becomes professor of chemistry three years later.