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now, to the best answerer at a special examination. He was elected, 

 in 1831, to the chair of Natural and Experimental Philosophy, which 

 he filled with distinguished ability till 1843, when he became a Senior 

 Fellow. In the year 1862 he became Yice-Provost, and in 1867, when 

 the Provostship became vacant by the death of Dr. Macdonnell, he 

 was chosen by the Government of the day to fill the place. He con- 

 tinned to discharge the duties of this important office with unwearied 

 assiduity till his death, which occurred, after a few days' illness, on 

 the 17th of January, 1881. 



Dr. Lloyd was President of the Royal Irish Academy from 1846 to 

 1851, and on the visit of the British Association to Dublin, in 1857, 

 he was elected to the Presidency of that distinguished Society. 



In 1856 the University of Oxford conferred on him the degree of 

 D.C.L., Honoris Causa, and in 1874 he received from the Imperial 

 Government of Germany the Cross of the Order Pour le Merite." 



Dr. Lloyd's most important contributions to science were made in 

 the departments of optics and magnetism. It will be convenient to 

 consider these subjects separately, taking the contributions to each 

 subject respectively in the order of time. 



His first contribution to optical science was a systematic work on 

 plane (as distinguished from physical) optics. It was entitled " A 

 Treatise on Light and Vision," and was published in the year 1831. 

 This book possesses a high scientific value. 



The year 1832 was distinguished in Dr. Lloyd's life by, perhaps, his 

 most remarkable single scientific achievement, namely, the experi- 

 mental proof of the phenomenon of conical refraction. The discovery 

 of conical refraction presents one of the instances — rare in the history 

 of physical science — in which theory was able not merely to account 

 for a phenomenon but to predict it. Reasoning mathematically on 

 the theory of Fresnel, and giving a suitable physical interpretation to 

 the mathematical results which he obtained, Professor (afterwards Sir 

 William) Hamilton deduced the remarkable consequence that, in 

 certain cases, the two rays into which an incident ray is usually 

 divided by a crystal are replaced by an infinite number of rays, form- 

 ing a luminous cone or cylinder. Anxious to submit this extra- 

 ordinary result to the test of experiment, he requested Dr. Lloyd to 

 undertake the experimental investigation of the phenomenon, It 

 would be impossible to give here a detailed account of the difficulties 

 attendant upon this inquiry. Suffice it to say that they were over- 

 come by the experimental ability of Dr. Lloyd, who succeeded in 

 giving a perfect experimental demonstration of this remarkable pheno- 

 menon in both its varieties. He also established experimentally the 

 law by which the polarisation of the rays composing the luminous 

 cone is governed. 



This successful investigation at once brought Dr, Lloyd to the front 



