Jean-Sylvain Bailly was born 15 September 1736 in Paris at the Louvre. He was the son of Jacques Bailly, an artist and supervisor of the Louvre. As Bailly’s family was involved with the arts, it was only natural he would follow in their footsteps, which he did initially, showing talent in poetry and letters. However, the intellectual Bailly, described as tall, serious, and firm in character, found he was more attracted to astronomy having been introduced to the field by the French astronomer Nicolas Louis de La Caille (sometimes spelled Lacaille). It was after this introduction that Bailly became enamored with everything related to astronomy.
Bailly’s interest in astronomy resulted in him being admitted to the Academy of Sciences where he proved to be an excellent student: He calculated that the next orbit for the appearance of Halley’s Comet would be in 1759, and he published a correction reducing La Caille’s observations of the zodiacal stars. Bailly also participated in the construction of an observatory at the Louvre. In addition, he published a number of books: A History of Ancient Astronomy (1775), Discourse on the Origin of the Sciences (1777), Discourse on Plato’s ‘Atlantide’ (1779, and A History of Modern Astronomy (1782). These achievements resulted in him being elected to the Académie Française (French Academy) in February of 1784.
As to Bailly’s physical description and character, one person wrote:
“The person of Bailly was tall, his countenance was serious, but majestic; and his character, although firm, was replete with simplicity. His disinterestedness was conspicuous on a variety of occasions; he conducted himself with great generosity towards his relations, and exhibited much benevolence to the poor during his magistracy, at which period he expended a considerable part of his private fortune.”
When the French Revolution erupted, Bailly found himself in the middle of the revolution. This resulted in him putting his love for astronomy aside and turning his attention to politics. He was elected to the Estates General in May of 1789, and, a month later, he was elected president of the National Assembly (a revolutionary group formed from members of the third estate). A few days after the formation of the National Assembly, he found himself presiding over the proceedings of the Tennis Court, an event where members of the National Assembly took an oath and pledged they would not disband until a new national constitution was drafted and implemented.
After the Bastille was stormed on 14 July 1789, a new government in Paris was established called the Commune. Under the Commune, Bailly was elected the first mayor of Paris and soon after presented King Louis XVI with a tricolor cockade and keys to the city, stating:
“I bring to your Majesty the keys of your good city of Paris. They are the same that were presented to Henry IV. He had reconquered his people, here the people have reconquered their king.”
Once installed as mayor, Bailly also began to record his daily actions, anxieties, and fears. For instance, on 18 August 1789, he wrote:
“Our provisions are very much reduced. Those of the morrow depend strictly on the arrangements made on the previous evening; and now amidst this distress, we learn that our flour-wagons have been stopped at Bourg-la-Reine; that some banditti are pillaging the markets in the direction of Rouen, that they have seized twenty wagons of flour that were destined for us.”
A few days later on 21 August, he noted:
“Having learnt that a barge with eighteen hundred sacks of flour had arrived at Poissy, I immediately dispatched a hundred wagons from Paris to fetch them. And behold, in the evening, an officer without powers and without orders, related before me, that having met some wagons on the Poissy road, he made them go back, because he did not think that there was a wharf for any loaded barge on the Seine. It would be difficult for me to describe the despair and the anger into which this recital threw me. We were obliged to put sentinels at the bakers’ doors!”
Bailly’s boldness made him popular with Parisians and they regularly cheered him when he appeared in public, but some people — Camille Desmoulins and Jean-Paul Marat — thought Bailly was too moderate and a monarchist at heart. He was also criticized for trying to promote his authority while at the same time limiting the powers of the Commune. In addition, he made a fatal mistake at the Champ de Mars on 17 July 1791 when he ordered the National Guard to suppress an assembly of revolutionaries who were demanding the monarchy be abolished. Rioters threw stones at the guardsmen who responded by firing into the crowd, wounding and killing some people. Revolutionaries saw his actions as a great betrayal, and it caused such a firestorm of controversy, Bailly was forced to resign as mayor of Paris.
After his resignation, Bailly retired to Nantes where he wrote an incomplete narrative related to his public life. These were later published — between 1821 and 1822 — in three volumes under the title of Mémoires de Bailly. While he was living in Nantes, the Commune decreed the house previously occupied by him as mayor, should have had taxes paid in the amount of 6,000 livres. The Commune then determined Bailly was responsible for the taxes, which he unwillingly paid. He was also placed under surveillance and “obliged [for a time] to present himself at the house of the Syndic Procurator of the Departmental Administration of the Lower-Loire.” Because of the political agitation in Nantes, Bailly decided to leave and moved to Mélun, settling there in July 1793.
Part of Bailly’s reason for leaving Nantes had to do with Bailly’s colleague, Pierre-Simon, Marquis de Laplace. He was an influential French scholar in the sciences and mathematics, and he wanted to sell his house in Mélun and move nearer the Seine River. About the same time, as Bailly left Nantes, the revolutionary army began marching to Mélun. Laplace warned Bailly that he should not come to Mélun, and told him that if he did, he would be arrested. Bailly ignored Laplace’s warning and stated upon his arrival in Mélun, “If I am to be arrested, I wish it to be in a house that I have occupied some time.”
Soon thereafter, Bailly was arrested and taken to Paris where he was incarcerated at Madelonnettes, and then later La Force. Attempts were also made to make him testify against Marie Antoinette. He refused. He was then taken before the Revolutionary Tribunal — a court instituted in Paris for the trial of political offenders — and found guilty of treason and sentenced to death.
On 12 November 1793, Bailly was taken to the Champs de Mars to be executed. This was the same site where he had suppressed the riot two years earlier, and revolutionaries selected this site because they believed he had betrayed them. It was a cold day. Rain had been falling steadily, and before he mounted the scaffolding one spectator cried out, “Thou tremblest, Bailly.” A drenched but stoic Bailly replied, “I am cold, my friend.”
-  Hays, Mary, and Sir Richard Phillips, The Annual Necrology, for 1797-8, 1800, p. 87.
-  Biographies of Distinguished Scientific Men, Volume 1, 1859, p. 181.
-  Ibid., p. 183.
-  Ibid., p. 183-184.
-  Ibid, p. 218.
- [6 Ibid., p. 223.
-  Ibid., p. 245.