Lloyd in 1831 succeeded his father as Erasmus Smith's Professor of Natural and Experimental Philosophy. At the meeting of the British Association in 1833 he spoke on his establishment by experiment of the existence of conical refraction in biaxial crystals, in conformity with the theory of William Rowan Hamilton. He also succeeded in establishing experimentally the law by which the polarisation of the rays composing the luminous cone is governed. 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 contributed to the theory of reflected light. 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, and in 1859 he described his investigation of the phenomena to the Royal Irish Academy When the magnetic observatory of Trinity College Dublin, was established under the auspices of his father, it was placed in Lloyd's 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 lobbying government to improve knowledge of terrestrial magnetism by establishing observing stations. He prepared the instructions for the observatories, and the officers appointed to take charge of them were trained by him in Dublin.
Later life
From 1846 to 1851 Lloyd was president of the Royal Irish Academy, who in 1862 awarded him their 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 Richard MacDonnell. He was president of the British Association in 1857, when it met in Dublin, and delivered an inaugural address, which was published, in which he gave a sketch of the recent progress made in astronomy, terrestrial magnetism, and other branches of science. Lloyd was a leading member of the general synod of the Irish church which came into existence on Irish disestablishment, and took part in its committee for the revision of the prayer-book. He died in the provost's house, Dublin, 17 January 1881.
Awards and honours
Lloyd 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. A bust of him, by Albert Bruce Joy, was placed in the library of Trinity College in 1892.
Works
In 1834 Lloyd furnished the British Association, at its request, with a report on The Progress and Present State of Physical Optics. Papers which he wrote on terrestrial magnetism and other subjects are in the Reports of the British Association and in the Transactions and Proceedings of the Royal Irish Academy. Besides tracts, his other published works were:
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.
