IVICERON (Joint FEAxcis,) in bio graphy, a French monk and inge nious mathematician in the seventeenth century, was born at Paris, in the year 1613. He early displayed a love of learn ing, and by the progress which he made in his elementary studies, afforded fair promise of future excellence. At the age of nineteen he entered into the or der of Minims, and before he had gone through his course of philosophy, disco vered that his predominant inclination was to the study of mathematical scien ces, to which, after he had completed his theological course, he devoted all the time that was not necessarily occupied by the duties of his profession. The science of optics was what principally en gaged his attention ; and he left behind him, in different houses belonging to his order, particularly that at Paris, some ex cellent performances, which afforded satisfactory evidence of his profound skill in this branch of the mathematics. He was twice sent on business to Rome, and was appointed regent of the philo sophical classes. Afterwards he was no minated to accompany father Francis de la None, vicar-general of the order, in his visitation of all the convents of Mi nims in France. The similarity of their taste proved the means of introducing him to the acquaintance of Des Cartes, who entertained a great regard for him, and made him a present of his " Prin ciples of Philosophy." Their intimacy, however, which commenced in 1644, proved but of short duration, since our young monk fell sick at Aix, in Pro vence, and died there in the autumn of 1646, when he was only thirty-three years of age. This event was lamented as a considerable loss to the republic of letters. He was the author of the follow.
ing works, which are held in high esti mation. " The Interpretation of Cy phers, or, a Rule for the perfect Under standing and certain explanation of all Kinds of simple Cyphers, taken from the Italian of the Sieur Anthony Maria Cospi, secretary to the Grand Duke of Tuscany ; enlarged, and particularly accommodated to the French and Spanish Languages," 1641, octavo; "Curious Perspective, or artificial Magic, produced by the won derful Effects of Optics, Catoptrics, and Dioptrics," &c. 1638, folio ; which was only introductory to his " Thaurnaturgus Options, sive, admirandx Optices, Catop trices, et Dioptrices, Pars prima, de tis gum spectant ad visionem directam," 1646, folio. On this work he was em ployed six years, and was prevented by his death from proceeding to the com pletion of the intended second and third parts, relating to the effects of reflection from plane, cylindrical, and conical mir rors, and the refraction of crystals. This task his friend father Mersenne under took, not only by correcting what Nice ron's papers in Latin and French would furnish towards it, but by supplying what might be necessary to perfect it. But the other occupations of this learned ma thematician, during the two remaining years of his own life, prevented him from finishing the work, which, upon his death, was committed for that purpose to M. de Roberval, professor royal of mathematics at Paris. A "Letter" of Father Niceron's is inserted in the third volume of Liceto's " De quzesitis per Epis tolas."