BOUGUER, PETER, a celebrated mathematician and natural philosopher, was born at Croisic, in the department of the Lower Loire, on the 10th of Feb ruary, 1698. At a very early age he was initiated into the study of the mathematical sciences, by his father, who was Royal Professor of Hydrography, and who had published, in 1698, an excellent and com plete treatise on navigation. Under such favourable circumstances, it was not surprising that Bouguer should have made rapid advances in his favourite study. We are told by the author of his Eloge, that when he was only 11 years old he gave instructions to his regent, in the Jesuits college at Vannes, and that at the age of 13 he detected an error committed by-a professor in mathematics ; but we require some infor mation respecting the regent and the professor, before we can estimate the merit of these juvenile efforts.
Upon the death of his father in 1713, young Bou guer was appointed Professor of Hydrography, and, at the early age of 15, he is said to have discharged the duties of his office with singular reputation. This situation was by no means given to Bougucr out of respect to the memory of his father. Pro fessor Aubert, who was charged by the minister with the examination of the young candidate, almost refused to listen to his pretensions, till Bouguer re minded him that knowledge was not confined to any particular age, and solicited a rigorous examination, during which he exhibited an extent of capacity and information which astonished his examinator.
In the small town of Croisic, the talents of Bou guer were almost buried in oblivion. lie aspired to a scat in the Academy of Sciences, without indul ging the hope of ever reaching the object of his ambi tion. A trifling accident, however, contributed to extend his fame, and to introduce him on a theatre more suited to the pre-eminence of his talents. Hav ing accidentally met with the celebrated Reyncau at Angers, the academician soon perceived the strength as well as the direction of his genius, and he conver sed with him on the different subjects of his studies, hut particularly on the roasting of ships, a subject which had occupied much of Bouguer's attention. Reyneau took frequent opportunities of mentioning in Paris the researches of Bouguer on the misting of ships, and obtained a reading of the memoire for M. Mairan, who had taken an interest in the young ma thematician. Mairan had influence enough to get this made the subject of the Academy's prize for 1727, which Bougucr, though only in the 29th year of his age, carried off against every competitor. In 1729, he received a similar reward for the best method of determining the height of the stars at sea. In his paper on this subject, which was pub lished separately at Paris, in 1729, under the title of De la maniere d' observer exactement sur mer la hauteur des -.hires, he claims the merit of having been the first who determined the path described by a ray of the sun, in its transmission through the earth's at mosphere ; but the solution of this problem had been given long before by our countryman Dr Taylor. This work was attacked, in 1732, by Meynier, a na val engineer, who proposed the use of a semicircle, instead of a quadrant, as employed by our author.* In the year 1729, Bouguer published his essay on the gradation of light, entitled Essai d'optique sur la gradation de la lumiere, which was republished by the Abbe de la Caille in 1760. This work is replete
with new views and ingenious experiments, and has been much esteemed by all experimental philosophers.
In the year 1730, Bouguer was removed to Havre, and from his proximity to Paris, he formed an inti mate friendship with several of the members of the Academy of Sciences, who recognized his distin guished abilities, and obtained for him the office of Associate Geometer, which was vacant by the pro motion of Maupertuis, in 1731. In the same year he published his prize essay on the best method of observing the variation of the compass ; and in 1734 appeared his Entretiens SW' in cause de inclina tion des orbites des planetes, which was the subject of the prize proposed by the Academy for 1732 and 1734. The abilities which were displayed in these different works procured for their author the office of Pensioner Astronomer in 1735, vacant by the death of M. Lictaud, and pointed him out as one of the most proper persons for carrying into execution the plan which the Academy had meditated, of mea suring a degree of the meridian in South America. He accordingly embarked at Rochelle, along with Go din, Condamine, and Jussieu, on the 16th of May 1735, and returned to his native country in June 1744, af ter an absence of nine years, during which he not only performed the part which was assignod him by the Academy, but took advantage of his situation among the lofty mountains of the Andes, to make a number of experiments and observations of a very in teresting nature. The first account of the operations of the three French mathematicians was published at London in 1739, under the title of A relation of the observations made at Quito on the obliquity of th Ecliptic, by M. Bouguer. These observations had been transmitted to our countryman Dr Halley, who caused them to be printed. In the Memoirs of the Academy for 1744 and 1745, Bouguer him self gave an account of his labours in America ; but it was not till 1749 that he published his great work, entitled La Figure de la Terre determines par les ob servations de 11/. 111 Bouguer et de la Condamine, par M. Bouguer ; which contains his theoretical investi gations respecting the earth's figure : and a full ac count of all the operations that attended the measure ment of a degree of the meridian in Peru. Condamine, the associate of his labours, was displeased with the pretensions of Bouguer, who seemed to withhold from his fellow-travellers their just share of reputation, and he asserted his own claims in his Journal Historiquc du Voyage a la Equateur, &c. Bouguer endeavoured to justify his narrative, in a work published in 1752, entitled Justification des Memoires de l'?cademie do 1744, et du /Pure de In figure de la terse, sur plusieurs faits gui concernent les operation des 4cademiciens. Condamine replied to this pamphlet in the same year, in his Supplement au Journal Historique du Voyage a l'Equateur, et au livre de la mesure des trois pre miers degres du meridien, Pour servir de reponse aux objections de M. Bouguer ; and he published the se cond part of it in 1754, in his Lettre dans laquelle on discute divers points d'astrononzie pratique, et remarques stir le supplement au Journal du Voyage de 111. de la Condamine ; and he was again answered by Conda mine, in a Reponse a la Lettre de M. Bouguer sur divers points de l'Astronomie partique et sur lc supfilc ment de M. Condamine.