Jean-Sylvain Bailly

French astronomer and politician

• Born: September 15, 1736
• Birthplace: Paris, France
• Died: November 12, 1793
• Place of death: Paris, France

Bailly, a renowned astronomer and historian of science, was elected president of the Third Estate in 1789. In the same year, he became the first mayor of Paris under the New Republic. He soon fell out of favor, however, and was later guillotined by the Revolutionary Tribunal of Paris.

Early Life

Jean-Sylvain Bailly (zhahn-seel-va bah-yee) was born into a family of painters to the royal court in Versailles. His father was court painter and custodian of the royal art collection at Versailles. Although it was originally understood that Jean-Sylvain would apprentice under his father and inherit his post, he showed little interest in art. Instead, he showed a strong aptitude for mathematics, and through a special arrangement he was tutored in calculus by Monsieur de Moncarville, whose son was in turn tutored in art by Jean-Sylvain’s father.

Bailly also had literary aspirations and as a teen penned two plays. The playwright Lanoue, after being shown the plays, told Bailly they were so poor he should burn them. From this point forward, Bailly focused most of his attention on the sciences and was soon drawn especially to astronomy by Abbé Nicolas Louis de Lacaille.

Life’s Work

Bailly made his first mark in astronomy by calculating the orbit of Halley’s comet when it appeared in 1759, a clear sign of his fascination for the mathematical side of astronomy. He calculated the orbits of several lesser comets as well. As a result of these and other astronomical observations and calculations, he was elected to the French Academy of Sciences in 1763.

Bailly continued his astronomical work, studying the orbits of the moons of Jupiter. It was well known that, despite careful observation, there were inconsistencies in their orbital paths. A number of astronomers had tried mathematical solutions. Bailly’s solution was elegant, considering the knowledge of the time (Laplace later found a better solution). He published two books dealing with the moons of Jupiter: Essai sur la théorie des des satellites de Jupiter (1766; essay on the theory of the satellites of Jupiter) and Mémoires sur les inégalités de la lumière des satelites de Jupiter (1771; memoirs on the uneven illumination of the satellites of Jupiter).

Bailly’s interests also strayed into questions concerning the ultimate fate of the Earth and the other planets. He postulated that each planet has an inner heat that is at some stage of cooling. Jupiter he considered too hot for life, and the Moon was too cold. Because the cooling was a continuing process, he believed that all the planets would eventually cool to the point where all matter would cease movement.

As his renown grew, Bailly was admitted to the French Academy and the Academy of Humanities. He developed a long-term relationship with Voltaire, later publishing many of the letters they exchanged. He also met Benjamin Franklin, a fellow scientist and politician.

During the 1770’s and 1780’s, Bailly published a number of books, including his most famous work, a three-volume history of modern astronomy, Histoire de l’astronomie moderne (1779-1782). This work followed his earlier Histoire de l’astronomie ancienne (1775; history of ancient astronomy). In a book on Indian and Oriental astronomy, he showed that the ancient Vedic astronomical tables not only were very accurate but also were probably of ancient origin. He was also fascinated with Plato’s writings on Atlantis in the Critias (360-347 b.c.e.; English translation 1793), and he wrote a book resurrecting Plato’s theories about the origin of Atlantis, Lettres sur l’Atalantide de Platon et sur l’ancienne histoire de l’Asie (1779; letters on Plato’s Atlantis and the ancient history of Asia). Bailly also speculated that the ancient Eden of the Bible was polar and claimed evidence from ancient Egyptian and Syrian manuscripts as support.

In 1789, the French Revolution exploded, bringing an abrupt change to Bailly’s life. Because of his fame as a scientist and his high level of integrity, he was catapulted into politics. On May 5, 1789, Bailly was elected president of the Third Estate, the assembly (somewhat like the British parliament) that represented the larger part of the French population. As a member of the bourgeoisie, the upper-class citizenry that often served on the Third Estate, he served as a political link between the working classes and the First and Second Estates (the clergy and the nobility, respectively). On July 15, Bailly was again elevated, this time to mayor of Paris, the city’s first mayor of the New Republic.

With no experience as a politician, Bailly was now thrust into one of the most difficult political situations imaginable. Because of the new humanistic ideas of the Enlightenment, the expansion of the middle class leading to clashes with the aristocracy, and the serious governmental financial crisis, Paris was thrown into anarchy. The only advantage Bailly had entering office was that he was on relatively good terms with most of the political players from the French monarchy on down.

Conditions in Paris were unmanageable. The peasants and middle class had overthrown the city’s police powers by storming the Bastille, Paris’s notorious prison-fortress. With no police protection, many merchants’ shops were looted. Commerce came to a standstill. To make matters worse, the grain harvest had been very poor, and the city was short on bread. With the shortage, bakers raised bread prices to exorbitant heights, reflecting their increased costs but further enraging the populace.

At first, Bailly felt honored to serve as mayor, but reality soon set in. The first order of business was to secure the food supply, the most inflammatory source of unrest. To do this, Bailly and his administration enacted price caps on bread so the working classes could afford to eat. Then he began to troll far and wide for grain sources, even to the point of buying from other countries. At any given time, there was often only about a day’s supply of grain in the city. Bailly managed to keep the precarious nature of the situation from the people, hoping it would prevent further rioting.

The other pressing need was to restore order through reforming the municipal government of Paris. The previous administration was so bureaucratically complex that no progress could be made, so a completely new constitution had to be enacted. Even this process was fraught with difficulty, as each of the districts of the city wanted to retain autonomy. Bailly was a strong proponent of a centralized government with the mayor having broad powers, whereas the elected assembly he had to work with wanted a much-less-centralized power structure. Eventually, Bailly had to compromise, with the result that his office as mayor had very little power: The right to enact laws was retained by each of the city’s departments.

In spite of Bailly’s initial success, the instability of Paris grew worse. Establishment of a national guard was helpful, but when “royal troops” were sent to Paris with orders to kill civilians and then fall back, Bailly saw no choice but to respond more forcefully to the unrest. On July 17, 1791, Bailly imposed martial law. Rioting broke out everywhere, and it was on this fateful day that General Lafayette ordered his militia to fire on an unruly mob at the Champs de Mars. Twenty-four civilians were killed in the attack. Lafayette went into exile two days later, and Bailly’s reputation was irreparably damaged.

On September 19, Bailly was forced to resign as mayor. Refusing to exile himself, he left Paris and moved to Nantes, where he spent the next couple of years writing his memoirs. Late in 1793, he was arrested while visiting Laplace in Melun. He was tried on November 10 by the Revolutionary Tribunal. Two days later, on November 12, 1793, Bailly was led to the Champs de Mars so he could be executed on the spot where his crime was committed. He was marched before a jeering, rock-throwing mob for several hours and was later led to a place near the Seine, where he was guillotined.

Significance

Jean-Sylvain Bailly’s place in history has been nearly forgotten. His accomplishments in astronomy, although notable at the time, have lost much of their importance. His accomplishments in the history of astronomy have been more lasting, however, and his book on the subject remains a classic. His astronomical achievements are permanently commemorated by Bailly Crater, the largest crater on the near side of the moon.

Bailly’s greater significance was certainly the role he played in the French Revolution. Although a man of science, he was also a man of deep moral convictions. This trait was recognized by those who helped propel him into politics. His inexperience was both an advantage and a disadvantage. Not having ever served in office before, he was unsullied by the political machinations so common in politics, thus gaining the trust of the populace. On the other hand, his lack of experience made him an easy target for those who were more experienced at the game. In some ways, it is surprising that he survived in his role as mayor as long as he did.

Bailly’s lasting legacy lies in the fact that he stood by the people of Paris in one of their darkest hours. He was a voice of reason between the extremes of anarchy and monarchy. He helped shape the constitution that lay at the foundation of the New Republic. He also paid the ultimate price for his role. He could have gone into exile to Great Britain or elsewhere, but he chose to remain in France, where, at the age of fifty-seven, he was executed in the city he loved.

Bibliography

Brucker, Gene A. Jean-Sylvain Bailly: Revolutionary Mayor of Paris. Urbana: University of Illinois Press, 1950. A short overview of Bailly’s life during his political career from his election to the presidency of the Third Estate to his resignation as mayor of Paris.

Brush, Stephen G. A History of Modern Planetary Physics. 2 vols. New York: Cambridge University Press, 1996. Contains a few brief sections discussing some of Bailly’s astronomical research and theories.

Pulet, Ann L. Jean-Antoine Houdon: Sculptor of the Enlightenment. Chicago: University of Chicago Press, 2005. Contains pictures and discusses the bust sculpted in honor of Bailly’s election as mayor of Paris.