LOUIS ANTOINE DE,** a celebrated circumnavigator, was born at Paris in 1729. He was received advocate in the parliament of Paris, but soon abandoned the profession, and entered the army in the corps of musketeers. He associated much with Clairaut and D'Alembert, from whom he derived his knowledge of algebra and fluxions. At the age of twenty-five he published his treatise on the Integral Calculus, as a supplement and continuation of L'Hôpital's treatise Des infiniment petits. He was raised to the rank of major in the Picardy regiment. He went to London as secretary to the French embassy, and was chosen a member of the Royal Society. In 1756 he went to Canada as captain of dragoons, and aid-de-camp to the Marquis of Montcalm, and having distinguished himself in the war against England, was rewarded with the cross of the order of St Louis.

After the peace, when the French government conceived the project of colonizing the Molossines or Falkland Islands, Bougainville undertook to begin this establishment at his own expense. He began by landing some families of French Canadians; and the number of settlers was increased afterwards to 150. But this colony having excited the jealousy of the Spaniards, the French government agreed that it should be given up to them, on condition of their indemnifying Bougainville. Bougainville was then appointed to command the frigate La Boudeuse and the transport L'Etoile, on a voyage of discovery round the world. He set sail in November 1766, taking with him Commerçon as naturalist, and Verron as astronomer. This was the first voyage round the world performed by the French. Since the first circumnavigation by Magellan in 1519, and that of Drake in 1577, eleven other circumnavigations had been performed, part of them by the Dutch and part by the English. Having executed his commission of delivering up the Falkland Islands to the Spanish, Bougainville proceeded on his expedition, and touched at Buenos Ayres at the time of the expulsion of the Jesuits from Paraguay. Passing through the Straits of Magellan, he anchored for a week at Tahete, where the English navigator Wallis had touched eight months before. The numerous rocks and other dangers made him turn off to the N.E., and prevented him from continuing a westerly course, so as to pass through the channel which separates New Holland from New Guinea. In his general chart these two islands are laid down as one, although he possessed some information of the existence of the channel. Two years after, in 1770, Captain Cook sailed through this channel. The expedition having crossed all the meridians... Bougainville's account of the voyage (Paris, 1771, 4to) is written with simplicity, and in a temper which inclined him to view objects on the humorous side. The art of making astronomical observations at sea was then much less perfect than now, and, accordingly, Bougainville's charts are found to be erroneous, particularly in the longitudes. After an interval of several years, he again received a naval command and saw much active service between 1779 and 1782. In the memorable engagement of April 12, 1782, in which Rodney defeated the Count de Grasse, Bougainville, who commanded the Auguste, succeeded in rallying eight ships of his own division, and bringing them safely into St Eustace. After the peace he returned to Paris, and solicited and obtained the place of associate of the Academy. He had a project of making a voyage of discovery towards the north pole. As this did not meet with support from the French government, he sent his plan to Admiral Phipps. Phipps, however, followed a different course, but only reached the 80th degree of north latitude.

Bougainville obtained the rank of vice-admiral in 1791; and in 1792, having escaped almost miraculously from the massacres of Paris, he retired to his estate in Normandy. He was chosen a member of the Institute at its first formation, and, in consequence, returned to Paris. He succeeded Borda as member of the Board of Longitude. In his old age, under the government of Napoleon, he enjoyed the dignity of senator, and was created a count and member of the Legion of Honour.

Retaining his good-humoured liveliness and his mental faculties to the last, he died in 1814, aged eighty-five. He was married, and had three sons who served in the French army. His éloge is written by Delambre, in the Memoirs of the Institute.