224; Royal Society. 



of all opponents as well as friends. This remarkable contest was, 

 as might be expected, commenced and carried on by Professor Mac- 

 Cullagh, witliout his ever accepting that pecuniary assistance which 

 was frequently and warmly offered by others, but by him was grate- 

 fully declined. 



About the middle of September, he commenced working at a sub- 

 ject which he was anxious to free his mind from as soon as possible. 

 The heading of the paper remains : it is, " A Theory of Total Re- 

 flexion of Light. Ey James MacCullagh, Fellow of Trinity College, 

 Dublin. Re^ad May 24th, 1841." 



Confinement and over-work gradually produced disease, mental 

 as well as bodily ; and after a few days' illness, an end was put to 

 his career on the night of the 24th of October, in the 38th year of 

 his age. 



As it is understood that there will be given at the stated Meeting 

 of the Royal Irish Academy, in March next, a more lengthened 

 memoir of Professor MacCuUagh's life than could conveniently be 

 offered to the Royal Society now, I have contented myself with the 

 few facts and dates which have been thus rapidly stated ; and as I 

 am led to believe that there will be given to the publig on the same 

 occasion an accurate and detailed account of his scientific labours 

 and discoveries, which it has been found difficult (through want of 

 time) to put together in a satisfactory manner for our Meeting this 

 night, I will merely glance at some of the things done by him since 

 this Society awarded to him the Medal already mentioned, being 

 the highest honour in their power to bestow. My information is 

 derived chiefly from gentlemen who have attended to and profited by 

 his official teaching in the University of Dublin, and who, having 

 since attained distinction and station in that University, speak now 

 with a natural enthusiasm of their lost preceptor and friend. 



Since Professor MacCullagh obtained the Copley Medal, in ad- 

 dition to the different papers which he published in the Proceedings 

 and in the Transactions of the Royal Irish Academy, he has given 

 seven courses of lectures in different branches of Natural Philosophy, 

 in his capacity of professor of that subject, having for about eight 

 years previously filled the Chair of Mathematics in a manner which 

 those alone can fully appreciate who know what was the state of 

 mathematical knowledge in the Dublin University previous to his 

 election and what it is now, and who can compare the state in which 

 he found it with that in which he left it. I allude to these Lectures, 

 because it was in the delivery of them, that is, in the conscientious 

 and due performance of the proper duties of his calling, that Pro- 

 fessor MacCullagh is reported to have ever appeared to the greatest 

 advantage. It was there that he used to display the extensive in- 

 formation, the elaborate research, and the vast acquired treasures of 

 his highly cultivated mind ; and it was there that he most delighted 

 to turn to account the noble faculty of inventive genius with which 

 he was so eminently gifted, in improving, by means of it, every sub- 

 ject he ever handled. There is no one capable of appreciating such 

 subjects, and who enjoyeil the privilege of attending the courses 



