Bertha Swirles was born in Northampton on 22 May 1903. Like many in Northampton, her father worked in the leather trade (he died when his daughter was only 2). Her mother was a school-teacher and Swirles grew up in an environment in which it was not unusual for the women of the family to be well-educated. In 1915 Swirles went to the newly established Northampton School for Girls, becoming Head Girl, and in 1921 won a Clothworkers' Scholarship to Girton College Cambridge to read Mathematics. She graduated with first class Honours in 1924 and spent the following year studying Part II physics, attending lectures by J.J. Thomson and Rutherford.
Swirles began postgraduate research under R.H. Fowler, holding a Yarrow Fellowship 1925-1927 and Hertha Ayrton Research Fellowship 1927-1928. She was awarded her Ph.D. in 1929. It was an exciting time to be doing research in Cambridge, fellow research students of Fowler were P.A.M. Dirac and Subrahmanyan Chandrasekhar. Another research student in the Department was D.R. Hartree and he suggested her first research problem, studying the polarizability of atomic cores. Swirles's and Hartree's careers would cross a number of times and they became firm and lifelong friends. She spent the winter of 1927-1928 in Göttingen, where she worked under Max Born and Werner Heisenberg and met other leading continental workers in the new field of quantum mechanics.
In 1928 Swirles was appointed Assistant Lecturer in Manchester. Here she resumed her contact with Hartree who had also moved there. At Manchester E.A. Milne guided her into research on the absorption of radiation by a gas, working first on a highly degenerate gas then a partially degenerate one, and her work proved significant in the study of stellar structure. This was followed by similar appointments in Bristol (1931-1932) and at Imperial College London (1932-1933) before returning to Manchester in 1933 as Lecturer in Applied Mathematics. She remained at Manchester, again working with Hartree, until 1938 when she returned to Cambridge to take up a Fellowship and Lectureship in Mathematics at Girton. Hartree also returned to Cambridge in 1946, when he was appointed Plummer Professor of Mathematical Physics. Swirles remained at Girton for the rest of her career, serving as Director of Studies in Mathematics and Mechanical Sciences 1949-1969 (and Music, another interest of hers, 1939-1947). The close and friendly contacts with generations of students endured long after they had left Cambridge and sometimes were renewed when children of former students came to study at Girton. Jeffreys served on the Governing Body of the College and served as Vice-Mistress 1966 to 1969. She was appointed Life Fellow of Girton in 1969.
In 1940 Swirles married the eminent scientist Harold Jeffreys. As Bertha Jeffreys she continued to publish papers on quantum theory but her collaboration with her husband led to her most widely known publication, the textbook Methods of Mathematical Physics, which they co-authored. It was first published in 1946 and went through many editions, revisions and reprints, most recently in 1999. Jeffreys's research interests broadened to include seismology in collaboration with her husband, who was appointed Plumian Professor of Astronomy at Cambridge and knighted in 1953. Theirs was a long and happy marriage until his death at the age of 97 in 1989.
Jeffreys was an influential figure in women's education in Cambridge and in mathematics. She served as President of the Mathematical Association 1969-1970 and was elected a Fellow of the Institute of Mathematics and its Applications in 1968. She received honorary doctorates from the University of Saskatchewan in 1995 and the Open University in 1996. She died on 18 December 1999.
This catalogue has been compiled by Timothy E. Powell and Peter Harper, National Cataloguing Unit for the Archives of Contemporary Scientists, University of Bath. NCUACS catalogue no. 152/2/07.
Bequeathed by Lady Jeffreys, Dec. 1999. Catalogued by NCUACS, 2002-7.