Page 19 - Spring 2009

Table 3. Key image interference experiments
Young’s Double-slit Experiment (1807) Fresnel’s Biprism (1819)
Fresnel’s Double Mirror Experiment (1819) Lloyd’s Conical Refraction Experiment (1833) Lloyd’s Mirror Experiment (1834) Billet’s Split Lens (1858)
engine and Google were not productive. However discovery of the Cantor (1983) text, opened doors. With Cantor’s clue to whom Lloyd was, the power of our digital universe was unlocked and the questions, “Who was Lloyd and why is he cited?” were answered.
In 1812, Bartholomew Lloyd, Chair of Mathematics, used methods based on the calculus of Liebniz and the work of Laplace and Lagrange from his studies at the Ecole Polytechnique in Paris [Cantor (1983, 149)] to restructure the mathematics curriculum of Trinity College, Dublin. His efforts were successful in producing several excellent mathe-
Table 2. Humphrey Bartholomew Lloyd (1800–1881)
maticians such as his son Humphrey Lloyd (Fig. 6, Table 2) and the renowned William Hamilton (of the Hamiltonian fame). The fundamental importance of this endeavor was that it resulted in the recognition of the importance of math- ematical potential as a guide to the physical analysis of phe- nomena such as optics. In short, experiments, either based on theoretical expectations or designed to test theory, were introduced to mid-19th century optical science.
Although Humphrey Lloyd was acclaimed for his 1831 Treatise on Light and Vision published in London and unavailable to this author, he apparently had an improved and more wave theoretic interpretation of plane optics by 1834. (Note, that in the 19th century it was the date when the paper was read before the Royal Societies rather than the date of publication in the Transaction or Proceedings). Humphrey Lloyd’s most remarkable single scientific achievement
occurred in 1832, namely, the experimental proof of the phenomenon of conical refrac- tion, the production of a luminous cone of light by a crystal, predicted by the mathe- matical extension of the theory of Fresnel by Hamilton. This discovery was a rare instance in which theory was not only able to mathematically describe the phenome- non but to predict it. The experiment had been suggested by Hamilton to test his the- oretical predication of conical refraction. As stated in the Royal Science Obituary, 1881, “It would be impossible to give here a detailed account of the difficulties atten- dant upon this inquiry. Suffice it to say that they were overcome by the experimental ability of Dr. Lloyd, who succeeded in giv-
Fig. 7. The Lloyd Mirror Experiment schematic based on the text of Lloyd (1837) and the work of Mach (1926).
Fig. 6. Humphrey Lloyd (1800-1881), Provost of Trinity College Dublin, Clergyman of the State Church of Ireland and member of the Protestant Ascendancy, the British ruling class of Ireland.
Born: Dublin, Ireland (British)
Profession: Clergyman
Research: Natural Philosophy, optics, terrestrial magnetism Science Gold Medal (1818)
Trinity College: BA (1819); MA (1827); DD (1840) Oxford: DCL, Honoris Causa (1855)
Fellow (‘24)-Professor (‘31)-Provost (’67); Trinity College Fellow of the Royal Society (1836)
Fellow and president, Royal Irish Academy (1846-51) President of the British Association in Dublin ( -1857) German Cross of the Order “Pour le Mérite” (1874) Cunningham Medal of Royal Irish Academy (1862)
18 Acoustics Today, April 2009