JOHN FRANCIS, a French philosopher, was born at Paris in 1613. Having finished his academical studies, with a success which raised the greatest hopes of him, he entered into the order of the Minims, and took the habit in 1632; and, as is usual, he changed the name given him at his baptism for that of Francis, the name of his paternal uncle, who was also a Minim, or Franciscan. The inclination and taste which he had for mathematics appeared early. He began to apply himself to that science in his philosophical studies, and devoted to it all the time he could spare from his other employments, after he had completed his studies in theology. All the branches of the mathematics, however, did not equally engage his attention; he confined himself particularly to optics, and only learned of the rest as much as was necessary for rendering him perfect in this. There remain still, in several houres wherein he dwelt, especially at Paris, some excellent performances, which discover his skill in this way, and which make us regret that a longer life did not suffer him to carry it to that perfection which he desired; since one cannot help being surprised that he proceeded so far as he did, in the midst of those occupations and travels by which he was forced from it during the short space of time which he lived. He hath himself observed in the preface to his Thaumaturgus Opticus, that he went twice to Rome; and that, on his return home, he was appointed teacher of theology. He was afterwards chosen to accompany Father Francis de la Noue, vicar general of the order, in his visitation of the convents throughout all France. But the eagerness of of his passion for study put him upon making the best of all the moments he had to spare for books: and that wise economy furnished him with as much as satisfied him. Being taken sick at Aix in Provence, he died there Sept. 22. 1646, aged 33. He was an intimate acquaintance of Des Cartes. The following are his principal works: L'Interpretation des chiffres, ou regles pour bien entendre et expliquer facilement toutes sortes des chiffres simples, &c. 2. La perspective curieuse, ou magie artificielle des effets merveilleux de l'optique, catoptrique, et dioptrique. This is only an essay to the following work: 3. Thaumaturgus opticus, sive, Admiranda opticae, catoptrices, et dioptrices, pars prima, &c. Two other parts were intended to complete the latter work, but were unfinished at his death.

John Peter, so much celebrated on account of his Memoirs of Men illustrious in the Republic of letters, was born at Paris March 11. 1685. He was of an ancient and noble family, who were in very high repute about 1540. He studied with success in the Mazarine college at Paris, and afterwards at the college Du Plessis. In a short time, resolving to forsake the world, he consulted one of his uncles who belonged to the order of Barnabite Jesuits. This uncle examined him; and not disdaining of his election, introduced him as a probationer to that society at Paris.—He was received there in 1702, took the habit in 1703, and made his vows in 1704, at the age of 19.

After he had professed himself, he was sent to Montarges, to go through a course of philosophy and theology; thence he went to Loches in Touraine to teach those sciences. He received the priesthood at Poitiers in 1708. As he was not arrived at the age to assume this order, a dispensation, which his uncommon piety had merited, was obtained in his favour. The college of Montarges having recalled him, he was their professor of rhetoric two years, and of philosophy four.—In spite of all these avocations, he was humanely attentive to every call and work of charity, and to the instruction of his fellow creatures, many of whom heard him deliver out fit rules of conduct for them, not only from the pulpits of most of the churches within the province, but even from those of Paris.—In 1716, his superiors invited him to that city, that he might have an opportunity of following, with the more convenience, those studies for which he always had expressed the greatest inclination. He not only underlood the ancient but the modern languages; a circumstance of infinite advantage in the composition of those works which he has given to the public, and which he carried on with great assiduity to the time of his death, which happened, after a short illness, July 8. 1738, at the age of 53. His works are, 1. Le grand Febrifuge; or, a Dissertatio to prove that common water is the best remedy in fevers, and even in the plague; translated from the English of John Hancock minister of St Margaret's, London; in 12mo. This little treatise made its appearance, amongst other pieces relating to this subject, in 1720; and was attended with a success which carried it through three editions; the last came out in 1730, in 2 vols. 12mo, entitled, A Treatise on Common Water; Paris, printed by Cavelier. 2. The Voyages of John Ovington to Surat, and divers parts of Asia and Africa, containing the history of the revolution in the kingdom of Golconda, and some observations upon silk worms; Paris, 1725, 2 vols. 12mo. 3. The Conversion of England to Christianity, compared with its pretended Reformation, a work translated from the English; Paris 1729, 8vo. 4. The Natural History of the Earth, translated from the English of Mr Woodward, by M. Nogues, doctor in physic; with an answer to the objections of Dr Camerarius; containing also several letters written on the same subject, and a methodical distribution of fossils, translated from the English by Niceron; Paris, 1735, 4to. 5. Memoirs of Men illustrious in the Republic of Letters, with a critical account of their works; Paris, 12mo. The first volume of this great work appeared in 1727; the others were given to the public in succession, as far as the 39th, which appeared in 1738. The 40th volume was published after the death of the author, in 1739.