**Sheila Power**'s parents were Michael Power and Christina Cunniffe. Let us note at this point that she became Sheila Tinney after her marriage but we shall refer to her by the name of Power until we reach the time when she married. Michael Power had been appointed to the Chair of Mathematics at University College Galway in 1912 and he held this position for over forty years until he retired in 1955. Christina was very musical and an excellent pianist. Sheila was the fourth of her parents' six children. Her mother died in childbirth in 1930 when Sheila was twelve years old [3]:-

Sheila was educated at the Dominican College of Taylor's Hill in Galway. This girls' Roman Catholic school had been founded by the Dominican Sisters in 1858 and, in keeping with the Dominican philosophy of education, aimed to give an education for the whole person. From the Dominican College of Taylor's Hill in Galway, Sheila went to the Dominican women's house in Cabra on the outskirts of Dublin. She sat the Leaving Certificate in 1935 and was awarded Honours in Mathematics. This may not look like a particularly great achievement but, to put it in perspective, we note that she was one of only 8 girls to receive this qualification in mathematics in Ireland in 1935 while 126 boys were successful. Even more surprising for a girl at that time, she entered the Arts Faculty of University College, Galway in 1935 to study mathematics. She then transferred to University College, Dublin in 1936 and graduated in 1938 being awarded a B.A. with First Class Honours in Mathematics. She also gained the distinction for being ranked first in her class.One of Sheila's fondest memories was of her mother playing the piano at home, and she became an accomplished pianist herself ...

Power continued to study at University College Dublin for her Master's Degree which she received in 1939. She was awarded a National University of Ireland travelling studentship prize which enabled her to undertake research for her doctorate with Max Born at the University of Edinburgh in Scotland. Born had been forced to flee from Germany when the Nazis came to power in 1933 and, after spells in north Italy and in Cambridge, he had been appointed to the Tait Chair of Applied Mathematics at Edinburgh in 1936. He had a number of Ph.D. students in addition to Sheila Power and he looked after them with great attention involving them in his latest research:-

Born and his students were involved in research on the stability of crystal lattices. Born wrote the first in a series of papers on this topic with the titleWhen Born arrived in the morning he first used to make the round of his research students, asking them whether they had any progress to report, and giving them advice, sometimes presenting them with sheets of elaborate calculations concerning their problems which he had himself done the day before.

*On the stability of crystal lattices I*which was published in the

*Mathematical Proceedings of the Cambridge Philosophical Society*in 1940. He writes:-

The second paper in this series was written by his student Rama Dhar Misra, the third by Born with Reinhold Fürth, the fourth by Born with Rama Dhar Misra, while the fifth and sixth were written by Reinhold Fürth. Reinhold Henry Fürth (1893-1979) was a Czechoslovakian physics professor at the German University of Prague before World War II but had come to the University of Edinburgh as a research fellow and lecturer. All six of these papers appeared in quick succession in theThe stability of lattices is discussed from the standpoint of the method of small vibrations. It is shown that it is not necessary to determine the whole vibrational spectrum, but only its long wave part.

*Mathematical Proceedings of the Cambridge Philosophical Society*in 1940 and 1941. The next in the series, published in the same journal in 1942, was by Power and it was entitled

*On the stability of crystal lattices. VII. Long-wave and short-wave stability for the face-centred cubic lattice*. She writes:-

A review of the paper by Lothar Wolfgang Nordheim (1899-1985) states:-I take this opportunity of expressing my sincere thanks to Professor Born for much valuable advice.

The next paper in the series, also in the same journal in 1942, wasIt is shown that a face centred cubic lattice, in which the forces fall off so rapidly with distance that only those between first neighbours must be considered, is stable against short wave displacements if it is stable against long wave deformations.

*On the stability of crystal lattices. VIII. Stability of rhombohedral Bravais lattices*by H W Peng and S C Power. It states:-

Huan Wu Peng was a Chinese student who had come to the University of Edinburgh to study under Max Born. Their joint paper was also reviewed by Lothar W Nordheim who writes:-This is part of a thesis presented by Miss S C Power for the Ph.D. degree in the Faculty of Arts, The University, Edinburgh.

Sheila Power had been awarded a Ph.D. by the University of Edinburgh in 1941 and in the same year she was appointed as an assistant lecturer at University College, Dublin. She was also given a part-time fellowship at the Dublin Institute for Advanced Studies which she took up on 1 October 1941. Recommended by Born, Huan Wu Peng took up a research fellowship at the Dublin Institute for Advanced Studies on the same day. A Colloquium was held in July 1942 at the Institute. Paul Dirac gave lectures on quantum electrodynamics and Arthur Eddington lectured on the unification of relativity and quantum theory.The stability of the Bravais lattices with rhombohedral unit cell of arbitrary angle is investigated under the assumption that the potential contains two terms, each proportional to a reciprocal power of distance. It is shown that among the cubic Bravais lattices contained in this group the face and body centred ones correspond to a minimum of potential energy, but the simple cubic lattice to a maximum. By numerical calculation of the energy of intermediate lattices it is shown that no other extrema for the potential energy exist and that the face centred lattice corresponds to the absolute minimum. Finally, equilibrium conditions for compound lattices with a number of parameters are formulated and it is shown, under assumption of the above form of potential energy, that these conditions can be divided into one set for change of volume and an independent set for change of shape.

When she first joined the staff at University College, Dublin, Power had a very heavy teaching load. This was not unusual at this time since most departments had large numbers of students taught by a small number of lecturers. She taught honours students studying mathematical sciences as well as teaching mathematics to large first year classes of engineers.

In 1944 Power published *Note on the Influence of Damping on the Compton Scattering* in the *Proceedings of the Royal Irish Academy. Section A: Mathematical and Physical Sciences*. At University College, Dublin, she was promoted to a statutory lecturer in 1945. She was awarded a fellowship to go to the Institute for Advanced Study at Princeton and, after obtaining permission for leave of absence from University College Dublin, she went to the United States. The records at the Princeton Institute for Advanced Study indicate that her visit started on 1 September 1948 and lasted until 30 June 1949 and that her field of study there was Nuclear Physics. Also at the Institute for Advanced Study at this time were, among others, Freeman Dyson, Albert Einstein, Harish-Chandra, George Uhlenbeck and Hermann Weyl. Many years later, Sheila Power would tell her students about her time at Princeton, queuing up for coffee with Albert Einstein.

The Royal Irish Academy was founded in 1785. Over the years, a small number of honorary women members were elected but no woman was allowed to become a full member until 1931 when, after taking legal advice, the Academy ruled that "in the existing state of the law women are eligible". Still no women were elected, however, until 1949 when four were elected, two scientists and two in the humanities. Sheila Power has the distinction of being one of these four. Despite her outstanding achievements, Power was not promoted at University College, Dublin, as one would have expected and many of her colleagues sympathised with her on not being made a professor.

In 1951 Sheila Power attended the Edinburgh Mathematical Society Colloquium held at the University of St Andrews. Her father Michael Power also attended this Colloquium as he had the 1938 Edinburgh Mathematical Society Colloquium held at the University of St Andrews, one year before his daughter went to undertake research in Edinburgh. Also at the 1951 Colloquium in St Andrews is Miss N Power who, we assume, must be a sister of Sheila Power. We note that R D Misra, who also worked in Born's research group at Edinburgh with Power, attended both the 1938 and 1951 Colloquia. Of those in the 1942 Dublin Institute photograph above, Arthur Conway, Pádraig de Brún and A J McConnell were also in St Andrews at the 1938 Edinburgh Mathematical Society Colloquium.

In 1952 Power married Seán Tinney who had been one of her former engineering students. Seán, who later became President of the Royal Dublin Society, shared his wife's love of music and had a fine singing voice. They had three children, Deirdre, Ethna and Hugh. Tinney taught postgraduate students in addition to her undergraduate teaching load. One of these graduate students, Philip McShane, writes [1]:-

Outside her academic duties, Tinney loved sports [3]:-I think now of my best graduate teacher, Sheila Tinney, who, as it happens, lectured in Feynman's home-zone, quantum electrodynamics. And, I fondly remember her diagraming, not on the board, but in the air between her and her two students! Luckily, a lot of the stuff was mirror-invariant. The other class-member was Lochlainn O'Raifertaigh(1932-2000)who later worked in the Institute of Theoretical Physics, Dublin, where Schrödinger worked before him.

Tinney continued her association with the Dublin Institute for Advanced Studies and she was appointed as a Research Associate in the School of Theoretical Physics of the Dublin Institute for Advanced Studies for the three year period from October 1954 to September 1957. She was eventually promoted to associate professor of mathematical physics (quantum theory) at University College, Dublin, in 1966.Tinney regarded exercise as intrinsic to life. She enjoyed the sociability of hill-walking, and more strenuous sports such as skiing and horse riding, and pursued them all wherever she happened to be. From all this, the only injury she regarded as significant was a concussion sustained when thrown by a horse which reared after disturbing a rattlesnake in the countryside near Princeton. She had a deep love of music and of literature, both of which she shared with her husband Seán ...[After their children were born]she replaced skiing and riding with tennis and golf.

Let us say a little about her children. Hugh Tinney is a concert pianist with a distinguished international reputation who performs regularly with both the RTÉ National Symphony Orchestra and the RTÉ Concert Orchestra. However, as a schoolboy he had found it difficult to decide which direction he should go. At school he loved sport, particularly tennis at which he excelled, as well as science and languages. He struggled to choose between mathematics, sport or music. His initial choice was mathematics which he studied at University for two years before deciding that he would change to music which he studied in London. For a time Ethna Tinney was a producer with RTÉ Lyric fm. Deirdre Tinney holds a PhD in political science from University College Dublin.

Sheila Tinney retired in 1978 when she reached the age of sixty. Her health began to deteriorate and in 1994 she was diagnosed with Alzheimer's disease [3]:-

She died on 27 March 2010:-This forced her gradual withdrawal into the privacy of family life, and eventually to the Molyneux Home, where she spent the last nine years of her life. She died peacefully there. She was predeceased by her husband Seán in2003.

Her funeral was held on 30 March 2010 after Mass at the Church of the Three Patrons, Rathgar, Dublin. She was buried in Mount Venus Cemetery....(very peacefully)in the wonderful care of the Matron and all the staff of the Molyneux Home, Leeson Park, Dublin6, after a long illness borne with fortitude and grace.

**Article by:** *J J O'Connor* and *E F Robertson*