Fr David Strong SJ, The Australian dictionary of Jesuit biography 1848-2015, Second Edition, 2017:
O'Leary, William

Teacher, seismologist; born Dublin, Ireland, 19 March 1869; died Sydney, 16 April 1939, aged 70.

William O'Leary was educated at Tullabeg and Clongowes; his father was a surgeon and a Member of Parliament. While at Tullabeg he developed an interest in science. He entered the Society at Dromore, 30 October 1886, did his juniorate at Tullabeg, 1888-90, studied philosophy at Louvain, 1890-93, where he did much experimental work with the inverted pendulum. He later taught mathematics and physics at Clongowes, 1893-99, studied theology at Milltown Park, 1899-03, and finished his studies with tertianship at Mold, Wales, 1904-05. In 1900 he published a textbook on mechanics.

In an obituary notice in the Monthly Notices of the Royal Astronomical Society, Vol.100, No.4, 1940, it said that O'Leary's 'mind ran on original lines. He was never content with stereotyped textbook solutions; he had to work out each problem for himself from first principles. In this way he was able to study many questions from a fresh angle and to develop original lines of research in various branches of science. Combined with this was a highly developed inventive talent and the ability to design new instruments and the skill to construct them.'

After studies, O'Leary taught physics, chemistry, and mathematics, and was assistant prefect of studies at Mungret, 1905-15, as well as director of the seismological and meteorological observatory. At the request of a Joint Committee of the British Association and the Royal Meteorological Society he carried out a series of upper-air investigations by means of sounding balloons. These were the farthest west observations had been made in Europe at the time.

One problem in seismometry was to obtain an instrument with a fairly long period and consequent high sensitivity. O'Leary provided a satisfactory solution by constructing a two-component horizontal seismometer with trifilar suspension. One of these instruments was completed in Mungret in 1911.

Later, he lectured in mathematics to the juniors at Rathfarnham, 1915-18, and started a seismological observatory. His 'O'Leary Seismograph' was at that time the first and only one in the world. He also worked with Professor John Milne at the Shide Observatory in the Isle of Wight, and from whom he acquired the Milne-Shaw seismography for his own seismography station at Rathfarnham. With these two seismographs, O'Leary was able to supply earthquake information to the whole country.

The need for accurate timing in seismology turned O'Leary's attention to chronometry. He saw that the secret of precision timing was to be sought in a free pendulum. He was one of the pioneers in the development of the free-pendulum clock in 1918.

O'Leary was minister, procurator and teacher at Belvedere, 1918-19, and then lectured in mathematics and physics to the philosophers at Milltown Park, 1919-29.

He was appointed to the Riverview observatory in July 1929. Besides introducing various improvements in the seismological department, he initiated a programme of photographic research on variable stars in collaboration with the Boscha Observatory, Lembang. He also invented and built a blink comparator, which proved successful in searching for new variable stars. He discovered many new variable stars and published several papers on variables in the Publications of the Riverview and Lembang Observatories and in the Astronomische Nachrichten. Other inventions included a recording anemometer and a petrol gas plant.

Scientists and the general public appreciated O'Leary's lectures on astronomy and seismology. His light and humorous touch combined with his clarity of exposition to render even abstruse topics intelligible and interesting. Together with his scientific work, he found time to do good work as a priest. Many found him a wise counsellor, and a humble and lovable priest and colleague. He was a little man, happy, charming, and quite unassuming in spite of his deep knowledge and high reputation.

He remained at Riverview until his death in 1939, directing the observatory until 1937 when Daniel O'Connell became director. The end of his life occurred when he collapsed and died on the golf course just after driving off. The suddenness of his death was a shock to the community, but he had a heart condition for sometime. This did not prevent him from planing fresh research and for new instruments. The day before he died he discovered a number of new variable stars with his newly completed comparator, and that night worked at the telescope taking star photographs.

O'Leary was a member of the Royal Irish Academy, the Royal Society of NSW, the Société Astronomique de France, the Seismological Society of America, Past President of the NSW Branch of the British Astronomical Association, and a fellow of the Australian Nation Committee on Astronomy.

(Reproduced by permission of Fr David Strong SJ.)

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ANZCC note: Grave incorrectly states date of death as 24 February 1939.