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Kathleen Lonsdale FRS (1903-1971) was an early pioneer of X-ray crystallography, a field primarily concerned with studying the shapes of organic and inorganic molecules.

In 1945, Lonsdale was the first woman, along with biochemist Marjory Stephenson, elected as Fellow to the Royal Society. She was the first female professor at University College London, the first woman named President of the International Union of Crystallography, and the first woman to hold the post of President of the British Association for the Advancement of Science.

In 1956, Lonsdale was named a Dame Commander of the Order of the British Empire (DBE), and in 1957 she received the Davy Medal of the Royal Society. In 1966, the "lonsdaleite", a rare form of meteoric diamond, was named after her.

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Marjory Stephenson FRS (1885-1948) was a biochemist and, along with Kathleen Lonsdale, was one of the first two women elected as a Fellow of the Royal Society in 1945.

Stephenson was a pioneer of chemical microbiology and wrote Bacterial Metabolism in 1930, which became a standard textbook for generations of microbiologists. She later co-founded the Society for General Microbiology and was elected as its second President in 1947.

Stephenson was also awarded an MBE for her work with the British Red Cross in France and Salonika during the First World War.

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To commemorate the 80th anniversary of the election of our first women Fellows, we’re highlighting landmark papers published by women in Philosophical Transactions that cover some of the key moments in scientific history.

Explore our interactive timeline.

Read the Royal Society's Meet the Changemakers (PDF) publication which celebrates leading women entrepreneurs.