seamus dubhghaill

Promoting Irish Culture and History from Little Rock, Arkansas, USA

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Birth of Astronomer William Edward Wilson

William Edward Wilson, Irish astronomer, is born at Greenisland, County Antrim, on July 19, 1851. He is the only son of John and Frances Wilson of Daramona House, Streete, County Westmeath, and is privately educated.

Wilson becomes interested in astronomy and travels to Oran in 1870 to photograph the solar eclipse. In 1871 he acquires a reflecting telescope of 12 inches (30.5 cm) aperture and sets it up in a dome in the gardens of Daramona House. He uses it to experiment on the photography of the moon with wet plates and also begins to study solar radiation using thermopiles. In 1881, he replaces the original telescope with a Grubb reflector of 24 inches (61 cm) aperture and a new dome and mounting that has an electrically controlled clock drive. The new telescope is mounted in a two-story tower attached to the house with an attached physical laboratory, darkroom and machine shop.

Wilson’s main research effort, in partnership with P.L. Gray, is to determine the temperature of the sun using a “differential radio-micrometer” of the sort developed by C.V. Boys in 1889, which combines a bolometer and galvanometer into one instrument. The result of their measurements is an effective temperature of about 8000 °C for the sun which, after correction to deal with absorption in the earth’s atmosphere, give a value of 6590 °C, compared to the modern value of 6075 °C.

Some of Wilson’s other astronomical projects include observations on the transit of Venus, determination of stellar motion, observations of sunspots and a trip to Spain to photograph a solar eclipse. He takes a great many excellent photographs of celestial bodies such as nebulae. His astronomical findings are published in a series of memoirs such as Experimental Observations on the Effective Temperature of the Sun.

Wilson is elected a fellow of the Royal Astronomical Society in 1875 and a Fellow of the Royal Society in 1896. He receives an honorary doctorate (D.Sc.) from the University of Dublin in June 1901. He serves as High Sheriff of Westmeath for 1894.

Wilson dies on March 6, 1908 at Daramona at the relatively young age of 56, and is buried in the family plot in Steete churchyard. He had married Caroline Ada in 1886, the daughter of Capt. R.C. Granville, and they have a son and two daughters. His son donates his telescope to the University of London, where it is used for research and teaching, finally becoming a feature in Liverpool museum.

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Birth of William McCrea, Astronomer & Mathematician

CREATOR: gd-jpeg v1.0 (using IJG JPEG v80), quality = 100Sir William Hunter McCrea, English astronomer and mathematician, is born in Dublin on December 13, 1904.

McCrea’s family moves to Kent in 1906 and then to Derbyshire where he attends Chesterfield Grammar School. His father is a school master at Netherthorpe Grammar School in Staveley. He goes to Trinity College, Cambridge in 1923 where he studies mathematics, later gaining a PhD in 1929 under Ralph H. Fowler.

In 1928, McCrea studies Albrecht Unsöld‘s hypothesis and discovers that three quarters of the sun is made of hydrogen and about one quarter is helium with 1% being other elements. Previous to this many people thought the sun consisted mostly of iron. After this, people realise most stars consist of hydrogen.

From 1930 McCrea lectures in mathematics at the University of Edinburgh. In 1931, during his time in Edinburgh, he is elected a Fellow of the Royal Society of Edinburgh. His proposers are Sir Edmund Taylor Whittaker, Sir Charles Galton Darwin, Edward Copson and Charles Glover Barkla. He wins the Society’s Keith Medal, jointly with Edward Copson, for the period 1939-1941.

In 1932 McCrea moves to Imperial College London as a Reader and marries Marian Core the following year. In 1936 he becomes Professor of Mathematics and head of the mathematics department at the Queen’s University Belfast.

During World War II McCrea is co-opted onto the Admiralty Operational Research Group. After the war, he joins the mathematics department at Royal Holloway College in 1944. He is elected a Fellow of the Royal Society of London in 1952.

McCrea is president of the Royal Astronomical Society from 1961 to 1963 and president of Section A of the British Association for the Advancement of Science from 1965–1966.

In 1964 McCrea proposes mass transfer mechanism as an explanation of blue straggler stars. In 1965, he creates the astronomy centre of the physics department at the University of Sussex.

McCrea wins the Gold Medal of the Royal Astronomical Society in 1976 and is knighted by Queen Elizabeth II in 1985.

William McCrea dies on April 25, 1999 at Lewes in Sussex. The McCrea Building on the Royal Holloway College campus is named after him.