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USSHER, HENRY (d. 1790), astronomer, a direct descendant of Arland Ussher, mayor of Dublin 1469–71, was fourth son of Samuel Ussher, rector of Dunganstown, co. Wicklow, by his wife Frances Walsh. His grandfather, John Ussher of Mount Ussher, third son of Sir William Ussher (d. 1671) of Portrane, co. Dublin, married, on 13 Oct. 1681, Alice, daughter of Samuel Molyneux, became a master in chancery, and died in 1745. Henry Ussher gained in 1759 a scholarship in Trinity College; graduated B.A. in 1761, M.A. in 1764, B.D. and D.D. in 1779; was elected to a fellowship in 1764, and co-opted senior fellow in 1781. Appointed, on 22 Jan. 1783, the first Andrews professor of astronomy in the university of Dublin, he repaired to London to order from Jesse Ramsden [q. v.] the instruments requisite for the designed new observatory. The chief of them were: a small achromatic telescope, mounted on a polar axis, and carried by a heliostatic movement; an equatoreal machine with circles five feet in diameter; a transit of six feet focal length, and a ten-foot vertical circle executed, after interminable delays, on a reduced scale [see Brinkley, John, (1763–1835)]. Ussher chose a site for the observatory at Dunsink, co. Dublin, planned the building, and supervised its construction. His stipend was fixed at 250l. per annum, out of which he undertook to defray all current official expenditure; but the board (consisting of the provost and senior fellows of Trinity College) made him, on 19 Feb. 1785, a special grant of 200l. His election as a fellow of the Royal Society of London on 24 Nov. 1785 followed close upon the incorporation of the Royal Irish Academy, of which body he was an original member. He died at his house in Harcourt Street, Dublin, on 8 May 1790, and was buried in the college chapel. His premature death, just as the initial difficulties of his career were overcome, was lamented as a calamity by men of science. The board allowed a pension to his widow, and promised grants of 50l. and 20l. respectively for the printing of his sermons and astronomical manuscripts. They ordered besides that his bust should be placed in the observatory, and proposed his death as the subject of a prize poem. But no publications ensued, and he remained without commemoration either in verse or marble.

Ussher married Mary Burne, and left three sons and five daughters. His eldest son was Admiral Sir Thomas Ussher [q. v.]

The undermentioned are the most important of the papers contributed by Ussher to the first three volumes of the ‘Transactions’ of the Royal Society:

  1. ‘An Account of the Observatory belonging to Trinity College, Dublin.’
  2. ‘A New Method of illuminating the Wires, and regulating the Position of the Transit.’
  3. ‘An Account of some Observations made with a view to ascertain whether Magnifying Power or Aperture contributes most to the discerning small Stars in the Day,’ translated in ‘Journal der Physik,’ 1791, iv. 54.
  4. ‘Observations on the Disappearance and Reappearance of Saturn's Rings in the Year 1789.’ From the compression of the globe he deduced a rotation-period for the planet of 10h 12½m.
  5. ‘An Account of an Aurora Borealis seen in full Sunshine.’ This unique phenomenon occurred on 25 May 1788.

[The Book of Trinity College, Dublin, 1591–1891; Taylor's History of the University of Dublin; Burke's Landed Gentry; Universal Magazine (Dublin), iii. 499; Watt's Bibl. Brit.; Cat. Grad. University of Dublin; Gent. Mag. 1790, p. 479.]

A. M. C.