Minutes of Proceedings. 375 



lion, in which he took a deep and thoughtful interest. His scientific 

 papers, many of which appeal only to that very limited circle of 

 students who possess the highest gifts alike of the physicist and of 

 the mathematician, were not published in the Royal Irish Academy, 

 where his work was principally directed to organizing and aiding the 

 magnetic observations and experiments which the Academy promoted 

 at Valencia. 



He was an acknowledged authority on nearly every branch of 

 physical science — optics, thermodynamics, the theory of solutions, 

 molecular physics — all were enriched by papers from his pen. His 

 name is perhaps best known as an exponent of the electro-magnetic 

 theory of light, and as a leader in sether-theory. 



To judge from the many acknowledgments of his great sympathy 

 and peculiar helpfulness that will be found in contemporary memoirs 

 in different branches of physical science, his death will be felt as a 

 personal loss, not only by his colleagues and associates, but also by 

 scientific men throughout the world. 



• Henry Hennessy, born in 1826, held for some years the Chair of 

 Natural Philosophy in the Catholic University of Ireland, and, in 

 1874, he was appointed to the Chair of Applied Mathematics in the Eoyal 

 College of Science for Ireland. He became a Member of the Academy 

 in 1851, and served on the Council from 1867 to 1874. He was 

 elected a Fellow of the Eoyal Society in 1858. 



His Papers published by the Academy were : — 

 1867 On the Distribution of Temperature in the Lower Eegion of 

 the Earth's Atmosphere. Trans., vol. xxiv, Science. 



And, in the Froeeedi?igs, the following : — 



1849 On the Influence of the Earth's Figure on the Distribution of 



Land and "Water at its Surface. 

 1856 On the Causes of certain Phenomena observed in Lough Erne. 

 ,, On Meteorology. 

 „ On the Influence of Latitude on the Position of the Isothermal 



Lines at the Surface of the Earth. 

 ,, On the Influence of the Earth's internal Structure on the 

 Length of the Day. 



E.I. A. MINVTES, SESSIOX 1900-1901. [35] 



