JEAN SYLVAIN, a celebrated philosopher and astronomer, was born at Paris on the 15th September 1736. He was originally intended for the profession of painting, which his family had pursued for several generations, and he even had made some progress in the art. But the bias of his mind leaned too much to literary pursuits, especially to poetry, and works of imagination, to permit him to give that application which is necessary to secure success and eminence in any profession.

The friends of Bailly, who had witnessed the early dawn of his genius, saw that it was equally fitted to appear with advantage in the study of polite literature, or to shine in the walks of science: and recommended the latter chiefly to his attention. His acquaintance with La Caille the celebrated geometer commenced, and this at once decided the object of his studies, which were now almost entirely devoted to scientific investigations. The first of his labours was the calculation of the comet which appeared in the year 1759. In January 1763, he was admitted a member of the Academy of Sciences; and in the same year he published a reduction of the observations made by La Caille in 1760 and 1761 on the zodiacal stars; an elaborate compilation, and of extensive utility. His attention was afterwards directed to the consideration of the theory of Jupiter's satellites. La Grange, who now promised to be the first mathematician in Europe, was the formidable rival of Bailly in the competition for this prize question in 1764. The results of his investigations were collected into a treatise, which also contained the history of that part of astronomy, and were published in 1766. In 1771 appeared his interesting and important memoir on the Light of the Satellites, which was marked with a degree of precision and accuracy till that time altogether unknown in the observations of their eclipses.

The studies of Bailly were not entirely limited to the cultivation of abstract science, or to profound physical Bailly. fical speculations; his genius shone with equal lustre in those departments of literature which require the rare talent of nice discrimination of characters, and no common power of eloquence, to reach excellence. The eloges which he composed for Charles V., Corneille, Leibnitz, Moliere, Cook, La Caille, and Greffet, were universally admired as valuable specimens of fine writing, and added much to his reputation. The distinguished place of secretary of the Academy of Sciences became vacant in 1771; and supported by the patronage and influence of Buffon, he offered himself a candidate. But here he was unsuccessful. Condorcet, who was then rising into reputation, and was supported by the active influence of D'Alembert, was preferred to the office.

In the year 1775, he published at Paris the first volume of the "History of Ancient Astronomy." The second volume of the same work appeared in 1787. In 1779 he gave to the world his "History of Modern Astronomy," from the foundation of the Alexandrian school to the present age. These works are of ineffable value, distinguished by animated description, luminous narration, and interesting detail. He also published a work entitled, "Letters on the Origin of the Sciences, and of the People of Asia;" which was afterwards followed by another series of "Letters on the Atlantis of Plato, and the ancient History of Asia," as a continuation of the same work. These volumes were addressed to Voltaire, with whom he had commenced an ingenious correspondence and discussion on this curious subject. The coincidence of his opinions with those of Buffon in points respecting some of the favourite theories of the latter, brought him into an intimate acquaintance and close friendship with that celebrated naturalist, which, however, declined and was entirely dissolved, in consequence of the opposition which Bailly made to the election of the abbé Maury into the French Academy. Bailly had been chosen secretary of this academy in 1784; and in the following year he was admitted into the Academy of Inscriptions and Belles Lettres. This was the only instance, since the time of Fontenelle, of the same person being at once a member of all the three academies.

In the year 1784 he was nominated one of the commission to investigate the nature of the animal magnetism of Mesmer, which was practised by Deslon; and he drew up an elegant report, which was presented to the Academy of Sciences. This report, which was soon afterwards translated into English, not only marked the acuteness and discernment of the author, and contained the most satisfactory and decisive evidence with regard to its object, but may be held up as an excellent model of imitation for those who are engaged in similar investigations. In developing the physical effects produced by moral causes, it is of the greatest value; and it is particularly interesting when we consider the political influence which causes of this nature have imposed on the general opinions of society, and even on the destiny of nations.

Hitherto we have contemplated Bailly in the shades of retirement, and in the calm undisturbed retreats of philosophy, employing the energy of a vigorous and comprehensive mind in the profound researches of physical truth: we are now to follow him in his political career, and behold him struggling with the adverse interests of party faction, and contending with the unbridled fury of a lawless mob, in defence of the rights of a people whose minds were not prepared to understand, and whose habits were not yet formed to enjoy, the blessings of rational liberty. He was one of the first and most zealous promoters of the revolution in France,—a revolution which not only astonished and convolved all Europe, but of which the immediate consequences to themselves, and to their country, were neither foreseen nor imagined by those who embarked in it, nor can its ultimate effects even at the present period be appreciated or conjectured,—a revolution which holds out an awful lesson to the leaders of popular factions to curb and repress, rather than to excite and encourage, that spirit of tumult and disorder among a people thrown loose from the necessary restraints of law, which bursts forth with ungovernable fury, and at last involves all in one general ruin. In the part which he acted in this bloody struggle, Bailly has had the good fortune to be well spoken of by opposite parties. He has not been charged with want of integrity or selfish designs in any part of his conduct; but actuated by a misguided zeal, and dazzled with the prospect of freedom which the warmth of imagination held out, he rashly stepped forward in a cause which he espoused with enthusiasm, and supported with his utmost exertions. But in that cause he fell a sacrifice to the unrelenting spirit of violence and party faction which had been roused, and which could neither be subdued nor regulated. When the states-general of France were assembled in 1789, he was elected a deputy to the Tiers Etat; was afterwards chosen president; and when the national assembly was constituted, he continued in the chair, and was president at the time that the king's proclamation was issued ordering them to disperse. During the struggle which took place between the popular part of the assemblies and the court, Bailly was among the most forward in asserting those popular rights which were then new in France; and he dictated the famous oath to the members of the Tiers Etat, "to resist tyrants and tyranny, and never to separate till they had obtained a free constitution." On the 14th of July following, the day on which the Bastile was stormed and taken by the people, he was appointed, with universal consent, mayor of Paris. In this high office, he is allowed to have discharged the arduous and difficult duties of it with great integrity, courage, and moderation. And while he held this conspicuous situation, he was a powerful agent in promoting the various measures by which the popular party prevailed over that of the court: and for this, and various other popular actions, he obtained a high degree of favour among the people. But the tide of public opinion now swelled beyond all bounds; no restraint could oppose its violent course. The multitude, unfettered by the fetters of despotism, fond of novelty, and with enthusiastic and unfettered notions of freedom, daily panting for change, could bear no opposition. Bailly, who perhaps now saw when it was too late the general disposition of the people to anarchy, still wished the laws to be respected, and hoped by their vigorous execution to restore and preserve tranquillity. He ordered some deputies from the military insurgents at Nancy to be arrested, and he firmly opposed the rash proceedings of Marat and Hubert; he be- came a member of a less promiscuous club than that of the Jacobins; and exerted himself strongly to persuade the populace to permit the king and royal family to depart to St Cloud. By these measures, which were little relished by a frantic and lawless people, he lost their confidence and favour. But what finally destroyed his popularity, was the tumultuous meeting of the populace on the 17th of July 1791, to demand the abolition of monarchy, when, being called by the national assembly to disperse the mob, who had assaulted the soldiery, he ordered the latter to fire, by which 40 persons were killed and above 100 wounded. Thus become obnoxious to the people whom he had faithfully served, it was no longer desirable for him to hold his charge. He therefore resigned his office at the dissolution of the constituent assembly in the end of the year 1791. After this period he lived in retirement, having resumed his philosophical researches. But the times of bloody proscription approached, and he must fall a sacrifice to the ferocious vengeance of the tyrant who now bore unlimited sway. He was accordingly denounced as an enemy to the republic, apprehended and thrown into prison. He was arraigned before a sanguinary tribunal, summarily condemned to death as a conspirator, and was executed the day following, near the spot where he had given the order for the military to fire on the people. On the day of execution, his sufferings, which he bore with the utmost calmness and magnanimity, were studiously protracted. Instead of that sympathy and compassion which even the worst and the lowest criminal often experiences when he is about to expiate his offences with his life, he was treated by an incensed and barbarous populace, with the most ignominious indignity and cruelty. He wore the red shirt, or badge of conspiracy, and was placed in a cart, with his hands tied behind his back. During the whole time of his progress to the place of execution, the rain poured incessantly on his head. The populace as he passed threw mud at him, and cruelly insulted him with every kind of opprobrious language. It was found necessary to remove the guillotine from the place where it was first erected to firmer ground. During this time he was forced to get out of the cart, and walk round the field, to gratify more fully the implacable and unrelenting malice of the mob. When he was ascending the platform, a spectator who was near him, in a tone of insult exclaimed, "Bailly, you tremble?" "Yes (he instantly replied), but not with fear."

Thus perished Bailly in the 57th year of his age. In his person he was tall, and of a sedate but striking countenance. He possessed great firmness and decision of character, but far removed from sullenness or apathy. Few philosophers have been more distinguished in so many various departments of science and literature, or have acquired such deserved reputation. In his public stations, as well as in the retirement of domestic life, his integrity and disinterestedness remained pure and untainted. In the time of his magistracy he spent part of his fortune in relieving the wants of the poor. His wife, whom he married in 1787, survived him. She was the widow of Raymond Gaye, who had been his intimate friend 25 years.