Page:A biographical dictionary of eminent Scotsmen, vol 9.djvu/71

Rh years at St. Andrews in the study of theology, and a third in Edinburgh, where he had Sir John Leslie for his class-fellow. But on completing his theological course, and leaving the university in 1786, instead of becoming a licentiate of the church, as his father had proposed, he became assistant teacher in a newly-established academy in Dundee, where he continued three years, and afterwards engaged with some other persons in a factory for spinning flax, which was erected at Douglastown, Forfarshire. How this last occupation, of which he was chief superintendent, coincided either with his previous studies as a theologian, or his predilections as a mathematician, does not distinctly appear; but the result was a failure; for, after fifteen years of trial, the company was dissolved in 1804, and the factory closed. During all this period, Ivory had probably employed his leisure in the study both of English and foreign works upon his favourite science pursuits not of a favourable nature certainly for the mechanical operations of flax-spinning. He had done enough, however, at all events, to show that his leanings were not towards the office of the ministry.

The next change that Mr. Ivory underwent was of a more congenial character, for it was to a professorship of mathematics in the Royal Military College, instituted a few years previous at Marlow, in Buckinghamshire. Here he laboured with great assiduity in his new charge, and afterwards at Sandhurst, Berkshire, when the college was removed to that quarter. The manner in which he discharged the duties of his important professorship not only met with the high approval of the governor of the institution, but also the cordial esteem of the students, whom he was never weary of instructing in a science so essential to the military profession. He endeavoured, in his lessons, to simplify those demonstrations that had hitherto been of too complex a character; and for the more effectual accomplishment of this purpose, he also published, but without his name, an edition of "Euclid's Elements," in which the difficult problems were brought more within the reach of ordinary understandings. So earnestly and indefatigably, indeed, were these duties discharged, that in 1819 his health unfitted him for further public exertion, and he resigned his chair in Sandhurst College before the time had elapsed that entitled him to a retiring pension. But the value of his services was so justly estimated, that the full pension was allowed him, with which he retired into private life, in or near London, where he prosecuted his favourite studies till the period of his death, which occurred on the 21st September, 1842, in the seventy-seventh year of his age.

Such were the few events of a public nature that characterized the life of Professor Ivory; but his actions are chiefly to be found in his scientific writings, which were highly estimated by the mathematicians of his day. Of these we give the following brief enumeration:—

In 1796, 1799, and 1802, he sent three communications to the Royal Society of Edinburgh. The first of these was entitled, "A New Series for the Rectification of the Ellipse;" the second, " A New Method of Resolving Cubic Equations;" and the third, "A New and Universal Solution of Kepler's Problem."

To these succeeded, between the years 1809 and 1839, fifteen papers, transmitted to the Royal Society of London, and published in their "Transactions." The first of these, " On the Attractions of Homogeneous Ellipsoids," possesses remarkable merit, in which he solved, in a new and simple manner, the attractions of these ellipsoids upon points situated on their exterior. Three of these