Page:Dictionary of National Biography volume 23.djvu/309

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Grozer worked occasionally in stipple, among these engravings being 'The Age of Innocence' and 'Sophia, Lady St. Asaph,' after Reynolds;' Sergeant Daniel McLeod,' after W. R. Bigg, and others.

[Chaloner Smith's British Mezzotint Portraits; Dodd's Memoirs of English Engravers (Brit. Mus. Addit. MS. 33401); Hamilton's engraved works of Sir Joshua Reynolds; Grozer's own engravings.]

L. C.

GRUBB, THOMAS (1800–1878), optician, was born at Kilkenny in Ireland in 1800. Having a strong bent towards mechanical engineering, he early abandoned mercantile pursuits, and his workshops in Dublin quickly acquired a high reputation. The originality characteristic of his designs was prominent in an ingenious machine for engraving, printing, and numbering the notes of the Bank of Ireland. He meanwhile acquired great skill in practical optics. One of the first reflectors equatorially mounted was the Armagh fifteen-inch erected by him in 1835. For the support of the mirror he devised a system of triangular levers, afterwards adopted by Lord Rosse, Mr. Lassell, and others. Among his other notable works were the Markree and Dimsink refractors, of thirteen and twelve inches aperture respectively; a twenty-inch reflector for the Glasgow observatory, and the equipment of nearly forty British magnetic stations under Provost Lloyd of Trinity College, Dublin. Lord Rosse frequently had recourse to his advice and assistance during the construction of his great specula. Grubb's latest was his most important performance. The Melbourne reflector, four feet in aperture, when completed by him in 1867, was surpassed in size only by the Parsonstown speculum, and still holds the primacy in the southern hemisphere. It is of the Cassegrainian form, equatorially mounted, and was declared, in the report of the committee to the Royal Society, to be a 'masterpiece of engineering' (Proc. Roy. Soc. xvi. 313). The metallic speculum suffered severely on the voyage to Australia. Some admirable lunar photographs have, nevertheless, been taken with it, and it has done good work in the observation of nebulæ.

Grubb retired from business in 1868, and was succeeded by his son, the present Sir Howard Grubb, F.R.S. He died at his residence at Rathmines, Dublin, on 19 Sept. 1878. The genial interest of his conversation had attracted to him many friends. He was elected a fellow of the Royal Society in 1864, and of the Royal Astronomical Society in 1870. His membership of the Royal Irish Academy dated from 14 Jan. 1839. He made interesting communications to the Irish Academy in 1852 and 1854 regarding the improvement of microscopes (Proc. R. Irish. Acad. v. 296, vii. 59); and read papers before the Royal Dublin Society in 1855 and 1858 'On Decimal Systems of Money,' 'On a New Patent View Lens for Photographic Cameras,' and on a 'New Table Microscope' (Journal Roy. Dublin Soc. i. 21, ii. 27, iii. 85). An account of his experiments on the adaptability of various kinds of reflectors to micrometrical use was laid before the Royal Astronomical Society on 11 March 1836 (Monthly Notices, iii. 177). He reported to the British Association, at its Dublin meeting in 1857, 'On the Improvement of Telescope and Equatorial Mountings,' and described advances made by himself in the optical details of both reflectors and refractors (Report, 1857, i. 195, ii. 8). The 'Journal' of the Photographic Society of London included essays by him 'On Lunar Photography,' and 'On Some of the Optical Principles involved in the Construction of Photographic Lenses' (iii. 279, iv. 108). A joint description by him and Dr. Robinson of the great Melbourne telescope was read before the Royal Society on 11 June 1868 (Phil. Trans. clix. 127).

[Nature, xviii. 570; Observatory, ii. 203; Athenæum, 5 Oct. 1878; Proceedings Roy. Irish Academy. 2nd ser. iii. 70; Roy. Society's Catalogue of Scientific Papers.]

A. M. C.

GRUFFYDD ab CYNAN (1055?–1137), king of Gwynedd or North Wales, was, through his father Cynan, son of Iago, a descendant of Rhodri Mawr and of the ancient royal line of Gwynedd. When a series of vigorous usurpers had occupied the North Welsh throne, Cynan took refuge among the Norsemen of Dublin, and, if we may trust the Welsh biographer of Gruffydd, married 'Raguell, daughter of Auloed, king of the city of Dublin and of a fifth part of Ireland, and of Man and many other islands.' It is plain, however, that after the battle of Cluantarbh no Danish king ruled over much of Ireland outside the Danish cities. Auloed, says Gruffydd's biographer, to whose rather doubtful testimony our knowledge of Gruffydd's early life is due, was the son of King Sihtric and a descendant of Harald Haarfagr. His wife was a daughter of King Brian. So that Gruffydd sprang from the noblest royal lines of Wales, Norway, and Ireland. He was born about 1055 at Dublin, and was nursed at a place called by the Welsh the 'Cymmwd of Columcille,' three miles from his parents' house. After Cynan's death his mother inspired him with the desire to emulate his father's exploits and save Gwynedd from