In late May and early June of 1790, two events seized the attention of Paris.
The first was the public proclamation by the Paris Police Prefecture that Inspector Javert had invented a new and remarkably efficient method of fingerprint identification. This technique, built upon the unique and immutable characteristics of human fingerprints, could now be used to verify identities and solve crimes. Several successful cases had already demonstrated its value.
The discovery quickly earned the formal endorsement of several leading scientists from the Académie des Sciences, whose own theoretical studies had laid the groundwork for such a method. The Palais de Justice, after reviewing a series of demonstrations, acknowledged the validity of the technique and authorised fingerprints to be admitted in court as decisive physical evidence.
The second great event was the announcement, published simultaneously in more than a dozen Parisian newspapers, of a scientific report by the Compagnie des Eaux de Paris. Its findings shocked the city—and soon, the entire nation.
The report concluded that the unclean water of the city's wells was the principal source of repeated outbreaks of cholera.
Louis Périer, the company's director, explained that he had commissioned a young mathematician named Joseph Fourier to compile a decade's worth of data—from 1780 to 1789—on the city's cholera epidemics. From this, Fourier produced a statistical analysis and a map of mortality, revealing that the vast majority of victims lived near public wells and springheads clustered within the central districts. Combined with corroborating evidence, he concluded that the city's well water was the vector through which cholera spread.
The publication ignited a storm of controversy. The well syndicates and their allied politicians were outraged, denouncing both Fourier and the water company as frauds. Yet the Académie des Sciences and the Hôtel de Ville remained silent.
A week later, under pressure from the Assemblée Constituante, the two institutions formed a joint commission to verify Fourier's data. After an extensive field investigation, the commission's report confirmed the essential accuracy of Fourier's Cholera Map. While it stopped short of declaring well water the definitive cause of cholera, it acknowledged a strong correlation—and, more importantly, praised the clean water distributed by the Paris Waterworks for drastically reducing the risk of epidemic disease.
The very next day, the company's two-year bonds skyrocketed. From barely one livre at the start of June, they surged to twelve. Behind the scenes, the architect of this miracle—André Franck—reaped an immense profit. His initial investment of thirty thousand livres had, in less than ten days, returned two hundred seventy thousand.
By mid-June, André fulfilled his agreement with the Périer brothers, investing two hundred thousand livres into their newly founded Société Unifiée des Machines à Vapeur, in which he now held a seventy-percent controlling share. The remaining sum was placed under the capable hands of the company's new managing director: Jean-Baptiste Say, not yet twenty-four years of age, a Lyonnais merchant's son who had studied commerce near London and become enamoured with the English Industrial Revolution and the ideas of Adam Smith.
The Périer brothers too emerged triumphant. Having joined André's financial operation, they profited handsomely from the market's frenzy. The municipal council, far from withdrawing its subsidies, increased them—and extended the company's exclusive concession by fifteen years. The crisis had transformed into a triumph.
Former opponents now lavished praise upon the Waterworks, while the well merchants, their influence broken, could do little but retreat in silence.
Fame came even more swiftly to Fourier.
The young man from Auxerre, who had once lived quietly as a provincial tutor, found himself celebrated across the capital overnight. His "Cholera Map" electrified the scientific community. At the Académie des Sciences, men such as Monge, Laplace, Lagrange, Lavoisier, and Legendre publicly praised the discovery, hailing it as a triumph of empirical reasoning and mathematical method.
Within weeks, Fourier was appointed to lecture at the Sorbonne, and several academicians urged that he be included in the soon-to-be-established National Commission on Weights and Measures—three years ahead of its official founding—to ensure that France's future standards would be guided by the mind of a true savant.
For Fourier himself, the accolades were bewildering. He knew he had merely served as a scribe. The true architect of the discovery, he believed, was his employer, Monsieur André Franck—a man who seemed capable of anything, who understood all things, save perhaps the higher geometry that so tormented him.
It was a paradox that amused him endlessly: in the Europe of the eighteenth century, every scientist was first and foremost a mathematician—and yet his own patron, the most brilliant man he had ever met, could barely tolerate an equation.
Detective Javert, whose fortunes had risen alongside André's, sought to ease the young scholar's discomfort. "Do not trouble yourself," he told him kindly. "André is the child of divine providence, the hand by which God dispenses His mercy. All you must do is swear to your own conscience that you will be faithful to him—and never betray the Apostle of Heaven."
There was sincerity in Javert's voice. Since entering André's orbit, the officer from Reims had prospered beyond measure. Only days earlier, Prefect Legoff had promised that by the time of the Fête de la Fédération in July, when the Police Prefecture would be reorganised into a full Police Directorate, Javert would be promoted from inspector to Deputy Chief of Police, one of six deputy commissioners under the new bureau.
Nor were the others forgotten.
Sergeant Hoche, upon completing his artillery correspondence course in mid-July, was to receive his commission as a lieutenant.
Sergeant-Instructor Augereau, whose stern methods had whipped the mounted constabulary into shape, was advanced one grade to staff sergeant.
Each of André's companions found their lives transformed, their careers elevated. Only André himself remained in a post with little formal power—the office of Tax Prosecutor. Yet even that seemed inconsequential beside the thirty thousand livres that had multiplied tenfold in a matter of weeks.
Still, the satisfaction proved fleeting.
Two hundred thousand livres had already been poured into the new steam-engine company; the remaining hundred thousand were demanded by the tireless Ouvrard, now operating in London. The young broker secured fifteen thousand for speculative investment in French assignats on the Exchange.
There were moments when André thought himself a fool. With such wealth in hand, he could have fled to a safer land, lived in comfort and idleness for the rest of his days. But something—an idea, an obsession—held him fast, as if bewitched. For that distant vision, that indefinable design, he would stake every coin he earned and every breath he owned.
Time moved quickly.
By late June 1790, André was preparing to travel south to Bordeaux, as arranged with Ouvrard. His official pretext was to assist the local court in a tax investigation—but in truth, the mission aimed to seize prime church lands along the Garonne Valley, particularly its fertile vineyards.
Then, a letter arrived—bearing the signature Louis Antoine Léon de Saint-Just—and altered everything.
André cancelled his planned journey at once. He wrote to Ouvrard, informing him that he would postpone his departure until after the national celebration of the Fête de la Fédération on July 14.
Saint-Just.
Yes—the same Saint-Just who would one day stand among the triad of Jacobin power, the "Archangel of Terror," the most beautiful and most merciless of Robespierre's disciples.
André's connection with him was long and curious. They had met years earlier at the University of Reims. In October 1787, Saint-Just—then a strikingly handsome student—was assaulted by a lecherous cleric. The young soldier's son struck his assailant senseless. The university, scandalised, sought to expel him. It was André, then serving as an assistant lecturer, who stood before the faculty tribunal and testified to the truth, saving Saint-Just's academic life.
From that day, the two became friends.
Saint-Just, two years André's junior, returned to his hometown of Blérancourt, but their correspondence continued. In September 1789, he published a satirical poem, Organt, mocking the Church and the feudal monarchy. André was his first reader in Paris.
In the spring of 1790, when Saint-Just was elected a colonel in the National Guard of the Aisne, André sent him five hundred livres in congratulations.
Now, in June, Saint-Just's new letter carried fresh news: he would soon arrive in Paris as the official delegate of Blérancourt for the Fête de la Fédération.
Enclosed was another letter—addressed to Deputy Maximilien Robespierre—which Saint-Just asked André to deliver in person.
The envelope bore no seal nor stamp.
Saint-Just had permitted André to read it.
In it, the future "Angel of Death" wrote with fervour:
"I do not know you, but you are a great man. You are not merely the representative of a province, but of the Republic—and of all humanity. You have sustained our weary country against the torrent of vice and conspiracy. Only a miracle allows me to know you—and I salute you."
Whether out of friendship or political foresight, André decided to remain in Paris until July 14, to meet Saint-Just and deliver the letter himself.
Since the Babeuf trial, André had encountered Robespierre twice in public. Once at a session of the Tax Commission, where he had boldly promised to reclaim sixty million livres from the tax farmers on behalf of the nation; and once again when, at the invitation of Prieur and Robespierre, he joined the Jacobin Club as its ninety-eighth registered member after paying a six-livre subscription fee.
Though a revolutionary by conviction, André regarded Robespierre with unease.
To him, the man radiated misfortune. Even in Robespierre's native Arras, his name would one day be whispered with shame. In André's own former world, the roof of the very hall that had once elected him to the Estates-General would be draped in black cloth—a mourning shroud that hung for two centuries in atonement for the blood spilled in his name.
Thus André had always kept his distance, avoiding unnecessary contact with the man who would one day claim to speak for virtue.
Since the Assembly's move from Versailles to the Tuileries, Robespierre had taken up residence at 30 Rue Saintonge, between the Hôtel de Ville and the Arsenal district, in a modest second-floor apartment. As his political stature rose, he had engaged a poor journalist and playwright, Pierre Villiers, to serve as his personal secretary.