December 17, 1900 - April 3, 1998

Mary Cartwright was born on December 17, 1900 in Aynho, Northamptonshire, England. She graduated from the University of Oxford in 1923, having attained a First in mathematics in only the second year that women were allowed to take Final degrees at Oxford. After teaching mathematics in the schools for four years, she returned to Oxford in 1928 for her D.Phil in mathematics under the supervision of G. H. Hardy and E. C. Titchmarsh, receiving the degree in 1930. Her thesis was on "The Zeros of Integral Functions of Special Types." This was published in two parts in the Quarterly Journal of Mathematics, Vol. 1 (1930) [Abstract] and Vol. 2 (1931) [Abstract]. After finishing at Oxford, Cartwright obtained a Yarrow Research Fellowship at Girton College, Cambridge University, where she continued her work on the theory of functions. In 1935 she was appointed a lecturer in mathematics at Cambridge. She held the position of University Lecturer from 1935 until 1959, and then Reader in Theory of Functions from 1959 until her retirement in 1968. During this time she was on the staff of Girton College, serving as Director of Studies in Mathematics and then as Mistress of Girton College from 1949 to 1968.

During the 1940's
Mary Cartwright worked
with John Littlewood on the solutions of the Van der Pol equation and
discovered many of the phenomena that later became known as "chaos".
In his review of Ian Stewart's book, *Nature's Numbers*, Dyson
writes about this work:

"Cartwright had been working with Littlewood on the solutions of the [ Van der Pol] equation, which describe the output of a nonlinear radio amplifier when the input is a pure sine-wave. The whole development of radio in World War Two depended on high power amplifiers, and it was a matter of life and death to have amplifiers that did what they were supposed to do. The soldiers were plagued with amplifiers that misbehaved, and blamed the manufacturers for their erratic behavior. Cartwright and Littlewood discovered that the manufacturers were not to blame. The equation itself was to blame. They discovered that as you raise the gain of the amplifier, the solutions of the equation become more and more irregular. At low power the solution has the same period as the input, but as the power increases you see solutions with double the period, and finally you have solutions that are not periodic at all."

Cartwright had a distinguished career in analytic function theory and university administration, publishing over 100 papers on classical analysis, differential equations and related topological problems. In 1947 Cartwright became the first woman mathematician to be elected as a Fellow of the Royal Society of England. She was elected President of the London Mathematical Society in 1951, received the Sylvester Medal of the Royal Society in 1964, the De Morgan Medal of the London Mathematical Society in 1968, and in 1969 became Dame Mary Cartwright (the female equivalent of a knighthood).

After her retirement Cartwright held visiting professorships at universities in England, America, and Poland. She died in Cambridge on April 3, 1998.

The following is a brief outline of Cartwright's mathematical work, summarized from the obituary by W. K. Hayman in the Bulletin of the London Mathematical Society

- Summability (4 papers)
- Cluster sets, limits and asymptotic values (11 papers)
- Level curves of integral and meromorphic functions (2 papers)
- Functions in the unit disk (6 papers)
- Entire functions (20 papers)

"This is the principal area in which Cartwright worked in the 1930s, and she established a considerable reputation here." - Ordinary differential equations (38 papers)

"...includes perhaps her most significant work. In the*Times*obituary her joint work with Littlewood was rightly described as ground-breaking work, making an important contribution to chaos theory." - Topology (4 papers)

"Cartwright and Littlewood's most significant work in this area was motivated by their study of differential equations." - History, biography and general (18 papers)

*Girton College Register*, Volume 2 1944-1969.- Hayman, W.K. "Obituary: Mary Lucy Cartwright," Bulletin of the London Mathematical Society, Vol. 34, No. 1 (2002), 91-107.
- McMurran, Shawnee L. and James J. Tattersall. "Mary Cartwright (1900-1998)," Notices of the American Mathematical Society, February, 1999, 214-220.
- McMurran, Shawnee L. and James J. Tattersall. "The Mathematical Collaboration of M.L. Cartwright and J.E. Littlewood," American Mathematical Monthly, Vol. 103, No. 10 (December 1996), 833-845. [Available at JSTOR (subscription required)]
- Dyson, Freeman. "Nature's Numbers by Ian Stewart," Mathematical Intelligencer, 19(2), 1997, 65-67.
- Watson, Jeri. "A Point of View: Mary, queen of maths," BBC News Magazine, March 8, 2013.
- "Personalities and Presidents," The Mathematical Gazette, Vol. 80 (March 1996), 22-23.
- Obituary, Daily Telegraph, London (April 11, 1998).
- Obituary, The Times, London (April 7, 1998).
- Mary Cartwright, Contributions of 20th Century Women to Physics (CWP)
- Author Profile at zbMath
- Mathematics Genealogy Project
- Biography at the MacTutor History of Mathematics Archive

Photo Credit: Photograph used with permission of the Mistress and Fellows, Girton College, Cambridge