Molyneux, William, Esq.

an excellent mathematician and astronomer, was born April 17, 1656, at Dublin, where his father, a gentleman of good family and fortune, lived*. Being of a tender constitution, he was educated under a private tutor at home, till he was near fifteen, and then placed in the university of Dublin, under the care of Dr. PaJliser, afterwards archbishop of Cashell. He distinguished himself here by the probity of his manners as

* His family were all lovers of treatise on gunnery, written by him.

learning. His father, Samuel, had an He died about two years before his son,

office m the court of exchequer, was in 1696. His grandfather, Daniel, was

master-^uuner of Ireland (an employ- Ulster king at arms, whom sir James ment which he held many years), and Ware calls " venerandce autiquitati

published “Practical Problems con- cultor.” He finished “Meredith Hancerning the doctrine of Projects design- mer’s Chronicle of Ireland.” but for

ed for great Artillery and Mortar whatever reason, the second part only

Pieces." It was printed on copper- was published, plates, and collected from a larger | well as by the strength of his parts; and, having made a remarkable progress in academical learning, and particularly in the new philosophy, as it was then called, he proceeded at the regular time to his bachelor of arts degree. After four years spent in this university, he came to London, and was admitted into the Middle Temple in June 1675. He staid there three years, and applied himself to the study of the laws of his country, as much as was necessary for one who was not designed for the profession of the law; but the bent of his genius, as well as inclination, lying strongly to philosophy and mathematics, he spent the greatest part of his time in these inquiries, which, from the extraordinary advances newly made by the Royal Society, were then chiefly in vogue.

Thus accomplished, hfc returned to Ireland in June 1678, and shortly after married Lucy, daughter of sir William Domvile, the king’s attorney-general. Being master of an easy fortune, he continued to indulge himself in prosecuting such branches of moral and experimental philosophy as were most agreeable to his fancy; and astronomy having the greatest share, he began, about 1681, a literary correspondence with Flamsteed, the king’s astronomer, which he kept up for several years. In 1683, he formed a design of erecting a philosophical society at Dublin, in imitation of the royal society at London; and, by the countenance and encouragement of sir William Petty, who accepted the office of president, they began a weekly meeting that year, when our author was appointed their first secretary. The reputation of his parts and learning, which by means of this society became more known, recommended him, in 1684, to the notice and favour of the duke of Ormond, then lord lieutenant of Ireland; by whose influence he was appointed that year, jointly with sir William Robinson, surveyor-general of his majesty’s buildings and works, and chief engineer. In 1685, he was chosen fellow of the royal society at London; and that year, for the sake of improving himself in the art of engineering, he procured an appointment from the Irish government, to view the most considerable fortresses in Flanders. Accordingly he travelled through that country and Holland, and some part of Germany and France; and carrying with him letters of recommendation from Flamsteed to Cassini, he was introduced to him, and other eminent astronomers, in the several places through which he passed. | Soon after his return from abroad, he printed at Dublin, in 1686, his “Sciothericum telescopium,” containing a description of the structure and use of a telescopic dial invented by him: another edition of which was published at London in 1700, 4to. On the publication of sir Isaac Newton’s “Principia” the following year, 1687, our author was struck with the same astonishment as the rest of the world; but declared also, that he was not qualified to examine the particulars. Halley, with whom he constantly corresponded, had sent him the several parts of this inestimable treasure, as they came from the press, before the whole was finished, assuring him, that he looked upon it as the utmost effort of human genius.

In 1688, the philosophic society at Dublin was broken up and dispersed by the confusion of the times. Mr. Molyneux had distinguished himself, as a member of it, from the beginning, by several discourses upon curious subjects; some of which were transmitted to the royal society at London, and afterwards printed in the “Philosophical Transactions.” In 1689, among great numbers of other Protestants, he withdrew from the disturbances in Ireland, occasioned by the severities of Tyrconnel’s government; and, after a short stay in London, fixed himself with his family at Chester. In this retirement he employed himself in putting together the materials he had some time before prepared for his “Dioptrics,” in which he was much assisted by Flamsteed; and, in August 1690, went to London to put it to the press, where the sheets were revised by Halley, who, at our author’s request, gave leave for printing, in the appendix, his celebrated theorem for finding the foci of optic glasses. Accordingly the book came out, 1692, in 4to, under the title of “Dioptrica nova: a Treatise of Dioptrics, in two parts; wherein the various Effects and Appearances of Spherical Glasses, both Convex and Concave, single and combined, in Telescopes and Microscopes, together with their usefulness in many concerns of Human Life, are explained.” He gave it the title of “Dioptrica nova,” not only because it was almost wholly new, very little being borrowed from other writers, but because it was the first book that appeared in English upon the subject. This work contains several of the most generally useful propositions for practice demonstrated in a clear and easy manner, for which reason it was many years much used by the artificers: and the second part it very | entertaining, especially in his history which he gives of the several optical instruments, and of the discoveries made by them. The dedication of the “Dioptrics” being addressed to the royal society, he takes notice, among other improvements in philosophy, by building it upon experience, of the advances that had been lately made in logic by the celebrated John Locke.

Before he left Chester, he lost his lady, who died soon after she had brought him a son. Illness had deprived her of her eye-sight twelve years before, that is, soon after she was married; from which time she had been very sickly, and afflicted with extreme pains of the head. As soon as the public tranquillity was settled in his native country, he returned home; and, upon the convening of a new parliament in 1692, was chosen one of the representatives for the city of Dublin. In the next parliament, in 1695, he was chosen to represent the university there, and continued to do so to the end of his life; that learned body having, before the end of the first session of the former, conferred on him the degree of doctor of laws. He was likewise nominated, by the lord-lieutenant, one of the commissioners for the forfeited estates, to which employment was annexed a salary of five hundred pounds a-year; but looking upon it as an invidious office, and not being a lover of money, he declined it. In 1698, he published “The Case of Ireland stated, in relation to its being bound by Acts of Parliament made imEngland” in which he is supposed to have delivered all, or most, that can be said upon this subject, with great clearness and strength of reasoning. This piece (a second edition of which, with additions and emendations, was printed in 1720, 8vo,) was answered by John Gary, merchant of Bristol, in a book called, “A Vindication of the Parliament of England, &c.” dedicated to the lord-chancellor Somers, and by Atwood, a lawyer. Of these Nicolson remarks that “the merchant argues like a counsellor at law, and the barrister strings his small wares together like a shop-keeper.” What occasioned Molyneux to write the above tract, was his conceiving the Irish woollen manufactory to be oppressed by the English government; on which account he could not forbear asserting his country’s independency. He had given Mr. Locke a hint of his thoughts upon this subject, before it was quite ready for the press, and desired his sentiments upon the fundamental principle on which his | argument was grounded; in answer to which that gentleman, intimating that the business was of too large an extent for the subject of a letter, proposed to talk the matter over with him in England. This, together with a purpose which Molyneux had long formed, of paying that great man ,*


We have an instance of a singular coincidence of opinion between Locke and Molyneux. Molyneux had a high opinion of sir Richard Blackmore’s poetic vein: “All our English poets, except Milton,” says he in a letter to Locke, “have been mere ballad-makers in comparison of him.” And Locke, in his answer, says, “I find, with pleasure, a strange harmony throughout, between your thought and mine.

whom he had never yet seen, a visit, prevailed with him to cross the water once more, although he was in a very infirm state of health, in July this year, 1698; and he remained in England till the middle of September. But the pleasure of this long-wished-for interview, which he intended to have repeated the following spring, seems to have been purchased at the expence of his life; for, shortly after, he was seized with a severe fit of his constitutional distemper, the stone, which occasioned such retchings as broke a blood-vessel, and two days after put a period to his life. He died October 11, 1698, and was buried at Sr. Audoen’s church, Dublin, where there is a monument and Latin inscription to his memory. Besides the “Sciotbericum telescopicum,” and the “Dioptrica nova,” already mentioned, he published the following pieces in the “Philosophical Transactions.” 1. “Why four convexglasses in a telescope shew objects erect,” No. 53. 2. “Description of Lough Neagh, in Ireland,” No. 158. 3. “On the Connaught worm,” No. 168. -4. “Description of a new hygrometer,” No. 172. 5. “On the cause of winds and the change of weather, c.” No. 177. 6. “Why bodies dissolved swim in menstrua specifically lighter than themselves,” No. 181. 7. “On the Tides,” No. 184. 8. “Observations of Eclipses.” No. 164 185. 9. “Why celestial objects appear greatest near the horizon.” No. 187. 10. “On the errors of Surveyors, arising from the variation of the Magnetic-needle,” No. 230. 1

Biog. Brit. Harris’s Ware. Martin’s Biog. Philos.