458 ADDRESS DELIVERED AT A MEETING 



Professor Mac Cullagh, and the general dynamical theory of Light 

 by the same author, mark an era in this branch of science not in- 

 ferior to that of Fresnel. 



Time will not permit me to do more than allude to the new 

 branch of analysis, which has recently engaged so much of the 

 attention of mathematicians, and which originated in the Theory 

 of Quaternions of Sir William Hamilton, and has received an im- 

 portant modification and development in the Triplet theory of 

 Professor Graves. As a Member of the University, I rejoice to 

 be able to add, that worthy successors, even to such men as I have 

 named, are arising there ; and that the recent union of the mathe- 

 matical strength of Cambridge and of Dublin in the Mathematical 

 Journal, which was so long and so ably supported by the former 

 University, is likely to give a new impulse to this branch of science 

 amongst us. And long may these sciences continue to flourish in 

 the University, and in this Academy ! Independently of the 

 magnitude and sublimity of their own proper objects, indepen- 

 dently of their direct value in Physical Science, as instruments of 

 research, they confer a no less important, but indirect service, in 

 disciplining the mind, and correcting those tendencies of other 

 portions of our mental constitution, which, when unbalanced, are 

 sure to mislead. 



Turning from the mathematical to the physical sciences, 

 and first of all to astronomy, which stands upon the confines of 

 both, we cannot fail to be struck by the fact, that in this one 

 Island, with all its disadvantages of climate, there are no fewer 

 than four Astronomical Observatories, each claiming a high place 

 in the history of European science; and that while, in other 

 countries, these costly institutions have been, with but few excep- 

 tions, founded and endowed by their respective Governments, in 

 Ireland (a country not certainly among the foremost in pecuniary 

 resources) they have been erected, equipped, and, with but one 

 partial exception, maintained by the munificence and public spirit 

 of individuals. The names of Mr. Cooper, and of the Earl of 

 llosse, will henceforward be added to those of Provost Andrews 

 and Primate Eobinson, as benefactors of science in this country ; 

 and Markree and Parsonstown be united to Armagh and Dublin 

 in the future history of Astronomy. 



The Dublin Observatory is the eldest of this noble sisterhood. 

 As respects its connexion with this Academy, I need not remind 



