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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.