# Dictionary of National Biography, 1885-1900/Lloyd, Humphrey (1800-1881)

​LLOYD, HUMPHREY (1800–1881), provost of Trinity College, Dublin, and man of science, eldest son of the Rev. Bartholomew Lloyd [q. v.], by Eleanor McLaughlin, was born in Dublin on 16 April 1800. Having received his early education at Mr. White's school, Dublin, he entered Trinity College there in 1815, gaining first prize, out of sixty-three competitors, at the entrance examination, which was at that time altogether classical. His college career was very distinguished. He obtained a scholarship in 1818, and graduated B.A. in 1819, taking first place and the gold medal for science, and proceeding M.A. in 1827, and D.D. in 1840. He became a junior fellow in 1824, and a senior fellow in 1843. He devoted himself especially to scientific study, and in 1831 succeeded his father as Erasmus Smith's professor of natural and experimental philosophy. During his tenure of this chair he sought successfully to improve the position of physical science in the university.
His own investigations in optics produced some remarkable results. At the meeting of the British Association in 1833 he gave an account of what was perhaps his most notable single scientific achievement (notice in Proceedings of Royal Society, vol. xxxi.), viz. his establishment by experiment of the existence of conical refraction in biaxial crystals, in conformity with the theoretical anticipations of Sir William Rowan Hamilton [q. v.] (see Report of the British Association for 1833; Transactions of the Royal Irish Academy, vol. xvii.; and Graves, Memoir of Sir W. R. Hamilton). He also succeeded in establishing experimentally the law by which the polarisation of the rays composing the luminous cone is governed. In 1834 he furnished the British Association, at its request, with a valuable report on ‘The Progress and Present State of Physical Optics’ (see Report for 1834). Shortly after, by means of an experiment on the interference of light proceeding directly from a luminous source, with light coming from the same source but reflected at a very high angle of incidence from a plane surface, he was able to make a most important contribution to the theory of reflected light (see Transactions of the Royal Irish Academy, vol. xvii.) A letter from Sir David Brewster led him to turn his attention to the phenomena of light incident on thin plates. In 1841 he submitted a communication on the subject to the British Association (see Report for 1841), and in 1859 he described his complete investigation of the phenomena to the Royal Irish Academy (see Transactions, vol. xxiv.)
In the field of magnetic research he was even more successful. When the magnetic observatory of Trinity College, Dublin, was established under the auspices of his father, it was placed in his charge, and the instruments for it were devised by him and constructed under his superintendence. He was a member of the committee of the British Association, at whose solicitation, in conjunction with that of the Royal Society, the government was induced to endeavour to improve our knowledge of terrestrial magnetism by establishing observing stations at various points in Great Britain and India. He prepared the written instructions for the conduct of the observatories, and the officers appointed to take charge of them were taught by him in Dublin the practical use of the instruments (see art. viii. Quarterly Review, lxvi. 271). It was largely owing to his efforts that the enterprise was successfully carried out. Many papers which he wrote on these and other subjects are to be found in the ‘Reports’ of the British Association and in the ‘Transactions’ and ‘Proceedings’ of the Royal Irish Academy. Of the latter body he was president from 1846 to 1851, and in 1862 he was awarded by it the Cunningham gold medal. He resigned his chair of natural philosophy in 1843, on his accession to a senior fellowship in Trinity College. In 1862 he became vice-provost, and in 1867 was appointed provost, in succession to Dr. Richard MacDonnell. He was president of the British Association in 1857, when it met in Dublin, and delivered an inaugural address, which was afterwards published, in which he gave a sketch of the recent progress made in astronomy, terrestrial magnetism, and other branches of science (see Report for 1857). He died in the provost's house, Dublin, 17 Jan. 1881. Lloyd was a leading member of the general synod of the Irish church which came into existence on disestablishment, and took a specially active part in its committee for the revision of the prayer-book.
In addition to the honours already mentioned, he was a fellow of the Royal Societies of London and Edinburgh, and an honorary member of many other learned societies of Europe and America. In 1855 the university of Oxford conferred on him the degree of D.C.L., and in 1874 the emperor of Germany the order ‘Pour le Mérite.’
He married, in July 1840, Dorothea, only ​daughter of the Rev. James Bulwer, rector of Hunworth-cum-Stody, Norfolk. He had no children. A bust of him, by Mr. Albert Bruce Joy, was placed in the library of Trinity College in 1892.
Besides several tracts, his published works comprise: 1. ‘A Treatise on Light and Vision,’ London, 1831. 2. ‘Two Introductory Lectures on Physical and Mechanical Science,’ London, 1834. 3. ‘Lectures on the Wave-theory of Light,’ two parts, Dublin, 1836 and 1841; republished, London, 1857, as ‘Elementary Treatise on the Wave-theory of Light.’ 4. ‘Account of the Magnetic Observatory at Dublin, and of the Instruments and Methods of Observation employed there,’ London, 1842. 5. ‘An Account of the Method of Determining the Total Intensity of the Earth's Magnetic Force in Absolute Measure,’ London, 1848. 6. ‘The Elements of Optics,’ Dublin, 1849. 7. ‘Address delivered at the opening meeting of the British Association for the Advancement of Science, held at Dublin 26 Aug. 1857,’ Dublin, 1857. 8. ‘Is it a Sin? An Inquiry into the Lawfulness of Complying with the Rule of the National Board relative to Religious Instruction,’ published anonymously, Dublin, 1860. 9. ‘The Climate of Ireland and the Currents of the Atlantic,’ a lecture, Dublin, 1865. 10. ‘Observations made at the Magnetical and Meteorological Observatory at Trinity College, Dublin,’ Dublin, 1865. 11. ‘The University of Dublin in its Relations to the several Religious Communities,’ anonymous, Dublin, 1868. 12. ‘The Doctrine of Absolutism,’ Dublin, 1871. 13. ‘Treatise on Magnetism, General and Terrestrial,’ London, 1874. 14. ‘Miscellaneous Papers connected with Physical Science,’ London, 1877.
[Proceedings of the Royal Irish Academy for 1881, v. 165; obituary notice prefixed to Proceedings of Royal Society of London, vol. xxxi.; private information; Dublin University Calendar.]
T. H.