SAUVEUR (Joseph)
, an eminent French mathematician, was born at La Fleche the 24th of March 1653. He was absolutely dumb till he was seven years of age; and then the organs of speech did not disengage so effectually, but that he was ever after obliged to speak very slowly and with difficulty. He very early discovered a great turn for mechanics, and was always inventing and constructing something or other in that way.
He was sent to the college of the Jesuits to learn polite literature, but made very little progress in poetry and eloquence. Virgil and Cicero had no charms for him; but he read with greediness books of arithmetic and geometry. However, he was prevailed on to go to Paris in 1670, and, being intended for the church, there he applied himself for a time to the study of philosophy and theology; but still succeeded no better. In short, mathematics was the only study he had any passion or relish for, and this he-cultivated with extraordinary success; for during his course of philosophy, he learned the first six books of Euclid in the space of a month, without the help of a master.
As he had an impediment in his voice, though otherwise endued with extraordinary abilities, he was advised by M. Bossuet, to give up all designs upon the church, and to apply himself to the study of physic: but this being utterly against the inclination of his uncle, from whom he drew his principal resources, Sauveur determined to devote himself to his favourite study, and to perfect himself in it, so as to teach it for his support; and in effect he soon became the fashionable preceptor in mathematics, so that at 23 years of age he had prince Eugene for his scholar.—He had not yet read the geometry of Des Cartes; but a foreigner of the first quality desiring to be taught it, he made himself master of it in an inconceivably small space of time. —Basset being a fashionable game at that time, the marquis of Dangeau asked him for some calculations relating to it, which gave such satisfaction, that Sauveur had the honour to explain them to the king and queen.
In 1681 he was sent with M. Mariotte to Chantilli, to make some experiments upon the waters there, which he did with much applause. The frequent visits he made to this place inspired him with the design of writing a treatise on fortification; and, in order to join practice with theory, he went to the siege of Mons in 1691, where he continued all the while in the trenches. With the same view also he visited all the towns of Flanders; and on his return he became the mathematician in ordinary at the court, with a pension for life.— In 1680 he had been chosen to teach mathematics to the pages of the Dauphiness. In 1686 he was appointed mathematical professor in the Royal College. And in 1696 admitted a member of the Academy of Sciences, where he was in high esteem with the members of that society.—He became also particularly acquainted with the prince of Condé, from whom he received many marks of favour and affection. Finally, M. Vauban having been made marshal of France, in 1703, he proposed Sauveur to the king as his successor in the office of examiner of the engineers; to which the king agreed, and honoured him with a pension, which our author enjoyed till his death, which happened the 9th of July 1716, in the 64th year of his age
Sauveur, in his character, was of a kind obliging disposition, of a sweet, uniform, and unaffected temper; and although his fame was pretty generally spread abroad, it did not alter his humble deportment, and the simplicity of his manners. He used to say, that what one man could accomplish in mathematics, another might do also, if he chose it.
He was twice married. The first time he took a very singular precaution; for he would not meet the lady till he had been with a notary to have the conditions, he intended to insist on, reduced into a written form; for fear the sight of her should not leave him enough master of himself. This was acting very wisely, and like a true mathematician; who always proceeds by rule and line, and makes his calculations when his head is cool.—He had children by both his wives; and by the latter a son who, like himself, was dumb for the first seven years of his life.
An extraordinary part of Sauveur's character is, that though he had neither a musical voice nor ear, yet he studied no science more than music, of which he composed an entire new system. And though he was obliged to borrow other people's voice and ears, yet he amply repaid them with such demonstrations as were unknown to former musicians. He also introduced a new diction in music, more appropriate and extensive. He invented a new doctrine of sounds. And he was the first that discovered, by theory and experiment, the velocity of musical strings, and the spaces they describe in their vibrations, under all circumstances of tension and dimensions. It was he also who first invented for this purpose the monochord and the echometer. In short, he pursued his researches even to the music of the ancient Greeks and Romans, to the Arabs, and to the very Turks and Persians themselves; so jealous was he, lest any thing should escape him in the science of sounds.
Sauveur's writings, which consist of pieces rather than of set works, are all inserted in the volumes of the Memoirs of the Academy of Sciences, from the year 1700 to the year 1716, on various geometrical, mathematical, philosophical, and musical subjects.
