After Brinkley had been appointed Bishop of Cloyne in 1826, Hamilton was immediately mentioned as his probable successor. Mr. Graves, to whom I am indebted for these particulars, assures us that Hamilton never put himself forward until a week before the election, when he received an urgent letter from his tutor, Mr. Boyton, to say that the Board were favourably disposed towards him. On the 16th June, 1827, the undergraduate of twenty-two, William Rowan Hamilton, was unanimously elected to the Chair of Astronomy. Nor was he without formidable competitors. Airy was a candidate, and so were some of the Fellows of Trinity College; yet a general approval, almost unanimous, ratified the choice of the Board. We say almost unanimous, because there was at least one weighty opinion on the other side. Bishop Brinkley thought that Hamilton had acted imprudently in accepting the post, and that it would have been wiser for him to have sought a Fellowship. With Hamilton’s life before us, we can now see that the Bishop was not right. The leisure and the seclusion of the Observatory were necessary conditions for Hamilton’s colossal labours. After his election to the Chair of Astronomy, Hamilton proceeded to his degree in the usual manner; but before doing so, he had, as an undergraduate, to perform the somewhat anomalous duty of examining graduates in the higher branches of mathematics for Bishop Law’s mathematical premium. The history of Dunsink Observatory for the next 38 years may be epitomised in a single word--Quaternions. It will be unnecessary to refer in any detail to the great career of our great mathematician. The early promise of the marvellous child and the brilliant career of the unparalleled student soon bore fruit in the congenial atmosphere of the Observatory. Conical Refraction, the Theory of Rays, the general method of Dynamics--any one of these researches would have conferred fame of which the greatest mathematician might have been proud, but with Hamilton these were merely incidental to the great work of his life. With huge industry he cultivated his powers, he wrought his mighty system of Quaternions, and found in it a weapon adequate to deal with the most profound mathematical problems of nature. It is not Hamilton’s fault if others have found that to wield this sword of a giant the arm of the giant is also necessary. Most of us feel satisfied if we know enough to be able to reverence the two awful volumes which every mathematician likes to see on his shelves, and which he generally leaves there.