The good Bishop died on the 13th September, 1835. He was buried in the Chapel of Trinity College, and a fine monument to his memory is a familiar object at the foot of the noble old staircase of the library. The best memorial of Brinkley is his admirable book on the Elements of Plane Astronomy. It passed through many editions in his lifetime, and even at the present day the same work, revised first by Dr. Luby and more recently by the Rev. Dr. Stubbs and Dr. Brünnow, has a large and well-merited circulation.
On the 4th August, 1805, a few years before the great circle was erected at the Observatory, William Rowan Hamilton was born in No. 36, Dominick Street, Dublin. He was educated by his uncle, the Rev. James Hamilton, at Trim, and his aunt, Jane Sidney Hamilton. The astounding precocity of the child is thus described by his biographer, Mr. Graves, to whose laborious and painstaking execution of his great task I must here make my acknowledgments. Of William Rowan Hamilton it is asserted that, “continuing a vigorous child in spirits and playfulness, he was, at three years of age, a superior reader of English and considerably advanced in arithmetic; at four, a good geographer; at five, able to read and translate Latin, Greek, and Hebrew, and loving to recite Dryden, Collins, Milton, and Homer; at eight he has added Italian and French, and given vent to his feelings in extemporised Latin; and before he is ten he is a student of Arabic and Sanskrit. And all this knowledge seems to have been acquired, not indeed without diligence, but with perfect ease, and applied, as occasion arose, with practical judgment and tact.”[107]
When Hamilton was seventeen years old (1822), he had written original mathematical papers, and with two of these—entitled respectively, “Osculating Parabola to Curves of Double Curvature,” and “On Contacts between Algebraic Curves and Surfaces”—he paid a visit to Dr. Brinkley at the Observatory. The Royal Astronomer was impressed by their value, and desired to see them in a more developed form. Thus originated an acquaintance between the scientific veteran, soon to be a Bishop, and the brilliant lad about to enter college.
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.
So great a personality as Hamilton has naturally gathered around itself much biographical interest. The intimacy between Hamilton and Wordsworth has given many interesting pages to Mr. Graves’ book, and how intimate the friendship became may be conjectured from the account of their first meeting. We are told how Hamilton walked back with Wordsworth to see him home after a delightful evening, and how Wordsworth then turned to see Hamilton back, and how the process was repeated I know not how often. It appears that Hamilton submitted his poetic effusions to his friend, and they were returned with gentle criticism, though with an occasional admission by Wordsworth that the mathematician’s verses possessed genuine feeling. Then there is the visit of Wordsworth to Dunsink, where to this day a beautiful shady walk bears his name. Hamilton enjoyed the privilege of intimacy with many cultivated intellects. He knew Coleridge; with Sir John Herschel he was in frequent communication; and he had many lady correspondents, including Maria Edgeworth. The bulk of Hamilton’s scientific correspondence was with the late Professor De Morgan, a man whose intellectual endowments were of such a different type to those of Hamilton, that, except in being both mathematicians, they had but little in common. On the death of Hamilton, De Morgan writes to Sir John Herschel (Sept. 13, 1865):—
“W. R. Hamilton was an intimate friend whom I spoke to once in my life—at Babbage’s about 1830; but for 30 years we have corresponded. I saw him a second time at the dinner you got at the Freemason’s when you came from the Cape, but I could not get near enough to speak.”[108]
The Observatory had the usual equipment of a transit instrument, a circle, and an equatorial, but no further additions were made to the instruments during the long sojourn of Hamilton. Observations were made by the assistant, Mr. Thomson, who, after a life passed in the service, retired in 1874, and lived a few years to enjoy the pension conferred on him by the Board. Just before Sir W. Hamilton’s death an important donation was received by the College. I shall here mention the circumstances under which it was made. The particulars were related to me partly by the donor himself, and partly by the late Earl of Rosse. The chief incidents in the narrative may be found in the life of De Morgan[109] to which I have already referred.
Sir James South was a medical man who acquired considerable wealth early in life, and then devoted himself with great assiduity to astronomy. He became an expert observer, and in conjunction with Sir John Herschel formed a series of double star measures that obtained much fame. Honours flowed in upon South; he received a pension and a knighthood; and he prepared for further astronomical work. His first care was to procure a superior telescope, and from Cauchoix, a French optician of renown, he procured an object-glass 12 inches in diameter, and possessing great optical perfection. For this lens, or rather pair of lenses, he paid either £800 or £1,000. South returned with this prize to his observatory at Campden Hill, Kensington, and commenced to have the mounting executed in a manner befitting the optical excellence of the lens. Brunel designed the revolving dome; it was made of mahogany, and cost, I believe, £2,000; and inside this building the eminent firm of Troughton & Simms were called upon to erect the telescope. But sad troubles followed, of which an entertaining account is given in De Morgan’s Life (p. 61), and the mounting was a dismal failure.