713 



he wanted to understand; at the same time showing him the pro- 

 position he was committing to memory for the next day's task. The 

 carpenter instantly sat down with the puzzled boy, and in a short 

 time showed him what a proof was. This was the way in which 

 Professor IMacCullagh first learned to prove a proposition in Euclid. 

 He was afterwards, when commencing his classical studies, sent to 

 LifFord to the school of the Rev. John Graham, and subsequently to 

 that of the Rev. Thomas Rollestone. He entered Trinity College, 

 Dublin, as a pensioner in November 1824, being then in the fifteenth 

 year of his age. In the following year, he became a candidate for 

 Sizarship, and was successful. Throughout his under-graduate 

 course he carried away every Honour both in Science and Classics. 

 In 1827, he obtained a Scholarship, and in 1832, (the year when his 

 Scholarship expired) he was elected a Fellow. In 1835, he became 

 Professor of Mathematics, Dr. Sadleir (the present Provost) having 

 resigned expressly to make way for him. In 1843, he was chosen to 

 fill the Chair of Natural Philosophy, in the room of the present Dr. 

 Lloyd, who, by becoming a Senior Fellow, was incapacitated from 

 continuing to hold it. In 1830, his first paper on Refracted Light 

 was read in the Royal Irish Academy, and shortly after he became a 

 Member of it, and contributed largely to place it in that position 

 v.'hich it now holds among the learned Societies of the world. In 

 1838, he obtained the Conjmgham Gold Medal from the Academy 

 for his paper " On the Laws of Crystalline Reflexion and Refraction," 

 which was presented to him, with an Address (since printed in the 

 Proceedings) respecting the then existing state of science in that 

 department, by Sir Wm. Rov^'an Hamilton, who was at that time 

 President of the Academy. In 1839, Professor MacCullagh may be 

 regarded as having laid the foundation of the highly valuable Mu- 

 seum of Irish Antiquities, now in Dublin, by presenting to the Royal 

 Irish Academy the celebrated Cross of Cong. In presenting the 

 Cross to the Academy, Professor MacCullagh stated, that his mo- 

 tive for doing so was, by putting it in the possession of a public 

 body, to save it from that shameful process of destruction to which 

 everything venerable in Ireland had been exposed for centuries, and 

 to contribute at the same time to the formation of a national col- 

 lection, the want of which, he had been told, was regarded by Sir 

 Walter Scott as a disgrace to a country so abounding in valuable 

 remains. He afterwards assisted in enlarging the Museum, which 

 he had thus (it may be said) commenced, by munificent subscrip- 

 tions. His contributions to the Academy were not confined to sci- 

 entific subjects ; they embraced matters of general literature, espe- 

 cially some connected with ancient Egyptian chronology. In 1842, 

 he was awarded the Copley Medal for his investigations on the 

 Theory of Light. Among the competitors were Bessel, Dumas, and 

 Murchison. On this occasion he was much indebted to Dr. Lloyd's 

 excellent report. 



In the following year, he was elected a Fellow of the Royal Society, 

 but was not a contributor to its Transactions. The reason frequently 

 assigned by him for this was, that he felt bound to do as much as 



