Fear of France

Must it be ever thus—that the source of happiness must also be the fountain of our misery? The rich and ardent feeling which filled my heart with a love of Nature, overwhelmed me with a torrent of delight, and brought all paradise before me, has now become an insupportable torment—a demon which perpetually pursues me.

—JOHANN WOLFGANG VON GOETHE, The Sorrows of Young Werther

Upon leaving Barcelona harbor Méchain’s precious repeating circles had been blasted by a bolt of lightning, and no sooner had he sailed within sight of neutral Genoa than an English frigate blockaded his vessel and forced her eighty miles south to the port of Leghorn (Livorno in Italian), where he and his fellow expedition members were placed in quarantine while customs officials threatened to impound his instruments.

Was ever a natural philosopher so beset by misfortune? Storms of fate, both natural and man-made, had forced him from the narrow meridian where his duty lay, and if the calamities of war and the frailties of his body were not enough to drive any man, even a natural philosopher, to helpless despair, these multiple woes were compounded by the knowledge of his own mistake, greater because it was self-inflicted, greater still because it was unrectified, and greatest of all because it was secret. A stoic natural philosopher might have coped with headstrong Revolutionaries, capricious generals, mischievous nature, and violent machinery; but the error for which he blamed himself was more than enough to plunge a sentimental natural philosopher—such as he—into a most profound melancholy.

Méchain was a stranger in Livorno, without acquaintances there. He could expect no help from his wife and colleagues in distant Paris; any letter to them would have to travel over the Alps, across battle lines, and through the thick of Revolutionary chaos. So, from the local lazaret—the compound where goods and visitors waited out their obligatory ten-day quarantine—he wrote to the director of the astronomical observatory in the nearby university town of Pisa, ten miles north in Tuscany.

Méchain could claim no prior acquaintance with Giuseppe Slop de Cadenburg. But the Pisan had long been a regular correspondent of Méchain’s maître Lalande and had also assisted the French navy with its Mediterranean maps, Méchain’s task for much of the past twenty-two years. They also shared a fascination with comets. So although they had neither met nor corresponded, the two men knew one another by reputation, always a savant’s most precious possession. As a scientific colleague, Méchain importuned Monsieur Slop to use his credit with the local authorities to get his instruments through customs. In return, he would visit Pisa upon his release to express his gratitude in person, and also to demonstrate the new astronomical repeating circle, should the Pisan wish to examine the most advanced scientific instrument of the day. The device was not contraband, and as his mission served the general good, it ought to be protected by all nations. “When war divides people,” Méchain wrote to Slop, “science and the love of the arts must reunite them.”

Such an eloquent plea and collegial connection was sufficient to unite two astronomers wherever they met. Slop sent an associate in Livorno to assist “the famous Méchain,” introducing him to top officials and negotiating the various payments—which some might call bribes—to clear his instruments through customs. A grateful Méchain arrived at the astronomer’s house in Pisa on June 22, 1794, the day of the summer solstice. He stayed for three weeks.

During this respite Méchain poured out his overburdened soul. Here at last was a sympathetic ear, as well as a knowledgeable astronomer. Méchain called Slop a kind of father, though he was only four years older. Virtuous, honorable, generous, good, venerable, worthy, with a noble simplicity of heart, and a bounty of wise counsel . . . , there was no end to the virtues Méchain ascribed to Slop, who practiced astronomy in Galileo’s former haunts. Slop had married a lively woman of English descent, Elizabeth Dodsworth, and they had raised their three children in an atmosphere of tolerance and freethinking. Francesco, the eldest, had been arrested the year before for dabbling in revolutionary politics. Now he was back in Pisa, supposedly working on astronomy.

His stay with Slop’s family reminded Méchain how much he missed his own virtuous wife and children. Yet this recollection was a bitter one, for in the same breath he also remembered how he had abandoned them to all the dangers of Revolutionary Paris. The contrast, he confessed to Slop, was painful. “I will tell my wife and our children that if they desire happiness they should pray that heaven aid my efforts to resemble a husband and father as respectable as you, so tenderly dear to his own family and to all those who have the advantage of knowing him.”

Méchain told Slop everything: his honorable motives for undertaking the mission, his unexpected misadventures along the way, his modest triumphs thus far, his growing frustrations with his assistants, even his tormenting doubts about the latitude measurements of Mont-Jouy and Barcelona. As a fellow astronomer, Slop understood the niceties of celestial observation—and the myriad ways that science might go wrong—yet he would not judge the results with the same critical eye as Méchain’s French colleagues, so concerned for the exactitude of the grand mission upon which all their reputations, careers, and perhaps even their lives depended. It was safe to confide in Slop. “You are the only one to whom I can speak so intimately,” Méchain would later write, “my only friend, the most worthy, the most virtuous, the most respectable.” To be on the safe side, he also swore Slop to secrecy, and later asked him to burn the wrenching letters in which “I opened my heart to you, as to a father.” It helped too that Méchain could be confident these letters would not be opened by the agents of the French Revolutionary state or find their way across the Alps to his colleagues in Paris. When read through the inevitable fog of self-deception, these letters offer a remarkable window into a man consumed by scientific doubt. In the days and weeks to come, he would confess his error at Mont-Jouy to Slop and to no one else.

Méchain’s immediate goal remained Genoa. He considered making the voyage by ship, but ultimately set out instead with his team on the overland route, a two-day ride by saddle horse. The coastal road skirted the edge of mountains suspended above the sparkling Mediterranean. The terrain was rough, and the instruments traveled separately by coach, arriving undamaged in Genoa just one day after Méchain, Tranchot, and Esteveny rode into town on July 11. That very evening, Méchain dined with the French ambassador and dispatched letters to his colleagues in Paris to ask for instructions, to Slop to tell him of his safe arrival, and to his wife to inform her of his whereabouts. He told them he planned to return to France as soon as possible and that everyone had assured him that the mail boat to Nice was perfectly safe. Given his recent mishap at sea, however, he preferred to wait for official instructions. He had not heard from Paris in a year. He knew nothing of the status of the meridian project, his own status, or that of his family. No one back home even knew he had left Spain. Letters took at least a week to travel between Paris and Genoa and sometimes much longer; many never survived the trip at all, producing that tangle of unreliable and delayed knowledge which is the stuff of tragedy or farce, depending on the circumstances—or a gnawing anxiety, if one is that way inclined. Anticipating a delay, Méchain went down to the customs house to extract clothing and linen from his trunks, and settled into the Albergo del Leon d’Oro (the Inn of the Golden Lion).

Genoa had once disputed dominion of the Mediterranean with Venice, and its vessels and bankers still traded from Gibraltar to the Levant. The spectacular semicircular harbor, with berths for scores of the largest vessels, formed an amphitheater at the foot of the Apennines. On a rocky promontory at one end of the harbor rose the spindly Lanterna lighthouse, like a Renaissance minaret four hundred feet tall. Most of the well-fortified town of 100,000 lived clustered near the harbor under blue slate roofs that mirrored the color of the sea. Strewn on the steep hills behind the town were sumptuous palaces and terraced gardens of orange trees. The prosperous city boasted an exquisite opera house and theater, plus plenty of street pageantry, from the annual San Giovanni procession to appease the floods of spring to the nightly promenade of elegant men and women along the ramparts. The nobles dressed all in black, with a short cape and no sword, and ruled the patrician republic as a tightly knit oligarchy. For the past century, however, the republic had been plagued by internal bickering, and French and Austrian armies had occupied the city in turn, obliging the patricians to trade the troublesome colony of Corsica to the French in order to preserve Genoa’s independence—this, two years before Napoleon’s birth on the island in 1769. Genoa still prided itself on its autonomy, and maintained a guarded neutrality as the French Revolution unleashed warfare across Europe. This neutrality pleased no one, of course. For the past year the English navy had intermittently blockaded the city. For his part, the French ambassador had been busy trying to incite the lesser nobles to challenge the ruling oligarchy, luring disaffected artisans to the French cause, and printing Jacobin propaganda in his basement. Meanwhile, eighty miles to the northwest of Genoa, the French army had attacked the Austrian and Piedmontese armies, according to the plan of a young general named Bonaparte.

Indeed, three days after Méchain reached Genoa, Napoleon Bonaparte arrived there too. He had come on a “diplomatic” mission to urge the Genovese to ally themselves with France—or else. He stayed a week, covertly casing the town’s fortifications and assessing Italian politics. The upstart national republic was threatening to supplant the venerable city republic.



“Veduta di Genova” by Ippolito Caffi. (From the Galleria Internazionale d’Arte Moderna di Ca’Pesaro, Venice)

While Méchain and his team waited for officials in Paris to decide their fate, the mail boat only brought word of fateful upheavals in the capital. On August 9—ten days after the event—report of Robespierre’s fall reached Genoa. For the moment, Paris was calm. Even this calm, however, could be variously interpreted. Tranchot hoped the radical cause would be regenerated now that Robespierre had been deposed. The engineer wrote to Francesco Slop, Giuseppe’s radical son, that despite the suppression of the Jacobins, “the same political order rules [in Paris] as it did before all these heads fell . . . , once again bringing despair to the aristocrats here who carry their head so high, but who will soon resume their usual bowing and scraping.” All across Europe, Tranchot boasted, French armies continued to advance. “Boisle-Duc is ours,” he noted, “as is Düsseldorf with its suburbs incinerated . . . , also the fortress of Coblenz, where the town will be razed the moment it falls into our power.” Closer to Genoa, the French army was bombarding Cúneo just eighty miles to the west.

Tranchot did more than sympathize with the radicals. During his stay in Genoa, he operated in concert with the French ambassador and cultivated young Francesco Slop for the French cause. The two men shared the hope that the Revolution would come to Italy. Tranchot advised his young recruit to bide his time.

I feel, as you do, the disgust of living out my life in a world for which you are not born. But you know as well as I that our revolution is not yet at that point at which a man should abandon the well-being he enjoys in his native country. That happy moment will come, however, and we may even hope that it will not be far off, for the basis for the new government seems gradually to be settling into a form which will inspire respect.

Beneath this faith in the Revolution’s promise lurked a deeper pain. Tranchot had reason to believe that much of his family had been imprisoned or killed in the Revolutionary violence of his native Lorraine, a fact that must never be mentioned, Méchain told Slop, because his subordinate would “think it ill-intentioned of me to have let it be known.” Relations between the two men had deteriorated since their departure from Spain. Tranchot’s health was as robust as ever, and he was impatient for Méchain to order the expedition back into action. It was tedious to wait for official instructions from Paris. He had had enough of Méchain’s fastidious perfectionism, his endless second-guessing, and his refusal to allow anyone else to conduct observations, perform calculations, or even look in the expedition logbook.

No word came from Paris that entire summer. Every Saturday the mail boat arrived with only the public newspapers in its satchel. As the weeks passed, Méchain grew anxious. “For a long time now I have been destined to languish in a state of uncertainty, destined to be tormented by the cruelest worries as to the fate of my family and the fate which awaits me.” These fears took many shapes. Had the meridian expedition been canceled? Might a jealous rival have denounced him to the Committee of Public Safety? It would not be difficult to make him appear culpable in their eyes: his long absence from France, his sojourn in countries hostile to the Republic, rumors that he had been offered a stipend and a position by the Spanish Crown, perhaps even whispers that his results were imperfect. No wonder he secretly asked Slop whether he might, if worse came to worst, seek refuge in some “obscure corner” of Pisa while he searched out a more permanent home for himself in exile.

In mid-August, he finally heard from his wife. She informed him that the meridian mission had been suspended “at least until spring,” and that only the Committee of Public Safety had the authority to revive it. On the one hand, nothing now prevented him from returning home. On the other, he feared she was concealing even worse news from him. “Perhaps she only embellishes the state of affairs to calm me down for a few moments.” He poured out his doubts to Slop, professing his innocence, swearing his love for his family, and cursing his wretched luck.

But forgive me; when I write to you I feel myself to be by your side, for it is the only moment when calm reigns in my heart. Oh, you know all too well what so cruelly torments and afflicts me. A virtuous, tender, and sensitive soul like yours feels all too well why I tremble as I approach my family, whereas under any other circumstances I would fly to them with transports of joy. It is the ardent desire to see them again which has made me break all my ties with them and separate myself for an indefinite period. Might not my return bring them new and more fearsome alarms; might I not trouble the little peace they now enjoy? How many frightening incidents and events will my return not present? May God not visit upon my family any of the harm which I might cause them.

He bared his soul to Slop. “You are now reading, Monsieur, into the very depths of my heart. You see there the sources of that fear which so strongly agitated me when I was with you.” He doubted whether he was worthy of the friendship and counsel of so benevolent a man as Slop. He begged indulgence for his weakness. His health, he noted, had been deteriorating rapidly these past several months.

Méchain’s spirits were not improved by the greetings sent by his colleagues on the Commission of Weights and Measures. At the end of August 1794 they finally sent him a copy of the law of August 1, 1793, which had established the metric system and which set the meter provisionally at 443.44 lignes. Moreover, they informed him that Delambre had been purged from the Commission, with no one assigned to take his place. Méchain drew his own conclusion: the meridian expedition, he decided, had been “definitively abandoned.” In which case, he had to wonder what purpose had been served by a mission “for which I have so tormented myself.” The little good he had hoped to accomplish had turned to ashes in his mouth, and his agony over the latitude of Mont-Jouy had become a bitter farce. “For it matters little now whether the latitude and longitude of Mont-Jouy be a quarter-minute too great or too little.” The new system of measures had already been established on the basis of the old measures of the meridian.

All of which throws my spirit into the most extreme disgust. The ambition to be useful and win a little glory, which once animated me, turns out to have been a vain fantasy. What interest will my feeble labors inspire in the Commission or in the government when they no longer serve any useful purpose? Why then should I remain zealous to continue this mission? My attachment to my family? Oh, why have they set me on this course which has led me God knows where? Oh, if only I had chosen another path, the one which presented itself to me most naturally, I would today be at peace and sheltered from all reproach or suspicion. My work would be interesting to both [my colleagues and the government], and all would pity me. But I wanted to get the best out of this project, the best for my colleagues, and for myself, and it may be that with the purest of motives I will have brought about the unhappiness of my family and myself without having contributed in the least to the success of the mission, and without any hope of recognition. Well, enough of this; the more I think on it, the less bright the future seems. My lot is cast, I wait upon the event, and console myself with my conscience, secure in the knowledge that my actions have always flowed from the best of intentions.

Yet the apparent cancellation of the mission, while it made all his labors meaningless, also brought a sense of relief: his measurements no longer mattered. If his efforts were to be buried in an unmarked grave, so too would their flaws. Indeed, the cancellation of the mission prompted Méchain to calculate how little difference his Catalan extension would have made to the estimate of the provisional meter. Now that the new standard had been set—albeit provisionally—what difference would his small addition make? “As you can see I add little, and any errors I committed in my small sector cannot have much influence, whether they cancel each other out or whether they are enormous; so that I am now trying to contain and calm the deadly disgust which is killing me.”

Then, the very next week, came the good news that returned him to the depths of despair, plus some truly black news that nearly finished him off. His supposition had been premature: the meridian project was being revived. He heard it from his wife and from Lalande. General Calon had been placed at the head of the department of military topography, with Méchain appointed chief of naval cartography at an annual salary of 6,000 livres, two months’ of which had already been paid to his wife. Tranchot had received a subordinate position in the new organization. Official news of this appointment arrived from Calon himself two weeks later, with this request: that Méchain return immediately to Paris so that they might discuss the future of the meridian project together.

As a practical matter, this promotion could only improve his family’s condition in the capital—where, his wife informed him, their provisions were running low—and it clearly gratified Méchain’s sense of self-worth. Yet he was not sure that a 33 percent pay hike would compensate for his added responsibilities. In his former humble job, he had only had to answer for the exactitude of his own work. Did he really wish to assume responsibility for the results of an entire department, conducted by men whose exactitude he could not vouch for? And how could he be sure this arrangement would outlast the next topsy-turvy twist of the Revolution? On top of this, Calon was ordering him to return to Paris, where he would surely have to turn over his data. “Oh, how well I see and feel why each man trembles for his own fate and for the interests that are dear to him, and why no one dares act.”

Worse, the revival of the meridian project meant that his mistake mattered again, that the discrepancy in the Mont-Jouy data was once more an affront to the accuracy of the meter, “the most important mission with which man has ever been charged.” So many reversals seemed to have upended Méchain’s mind. He admitted to Slop that he could barely think straight any more. “In my last letter to you I importuned you with my guessed-at results, and you saw the dying efforts of a downed combatant who still fights for a victory and a success that long ago eluded him. In picking myself up, shamefaced and dispirited, I can barely remember what I was running from or what I said.”

Most unsettling of all was the news that accompanied the announcement of the meridian project’s revival. Lalande confirmed that Lavoisier, Condorcet, and several other colleagues had been guillotined. Worse, Lalande informed him that the Terror had struck even closer to home—on the grounds of the Observatory, where his family still lived. Alexandre Ruelle, the young apprentice astronomer whom Méchain had taken under his wing, sheltered from the police, and trained for eight years, had denounced Cassini to the Revolutionary police, condemning his former protector to prison, and then capped his hideous betrayal by demanding that Cassini, Lalande, and Méchain be sent before the Revolutionary Tribunal and thence, inevitably, to the guillotine. Had Méchain been living in Paris at the time, the consequences would have been too awful to contemplate. At least Ruelle himself was now in prison—for his foul betrayal, for backing the radical party out of favor, and also for having committed a scientific error. Yet even after telling Méchain all this, Lalande still expected him to return to France that month.

Méchain also heard from other voices, friends who had sought refuge from the Revolution overseas. They urged him to join them in exile, to give up all hope of rescuing his wife and children, to cease to serve a country which had bloodied itself so horrifically.

[My friends] tell me I should count myself lucky if the Committee of Public Safety abandons me. They say that if the Committee spares my life, yet strips me of all my resources, exposing me to a thousand perils, that my wife, children, and I will come to seek death as the only way out of our misfortunes. They tell me that my return to Paris would do my family more harm than good. And they urge me, with great ardor, to follow them into exile. But my family, my duty, and my honor also call me, and I have always hearkened to their voices. Why should I repudiate them now . . . ? Why do such dire auguries traverse the seas to find me? Am I really so guilty?

The native son of verdant Picardy, dazed by the light of the summer Riviera, sat by the writing desk in his darkened hotel room and considered his dilemma from every angle. Emigration was a capital offense. Even the rumor that he was contemplating emigration might cost him his position, the livelihood his family depended on, and any hope of ever returning to France. Yet how could he return there now? He had been sent out on his mission with the best technology in the world. He had made himself personally responsible for the observations. And he had performed the calculations according to the most reliable methods. Yet the results were inconsistent. Méchain could not bring himself to blame the instruments or the calculations. He blamed himself. And if he blamed himself, then surely others would do so too. In a rare display of understatement he informed Slop: “I have been through some tough moments since I left you [in Pisa], but it is all my fault. I have placed myself in the hands of chance when I should have stuck to the path of certainty. One must suffer and not complain, or risk suffering still more.” He told himself to put the past behind him and think only of the present and the future. Yet he could not help but worry and he could not help but complain.


In early October the French ambassador to Genoa was recalled to Paris to account for his Jacobin sympathies, and his replacement, Ambassador Villars, arrived with funds and passports to speed the team’s return. The time had come to leave Genoa. Tranchot went down to the warehouse to pack the instruments for their voyage. Calon asked that the instruments travel across the Alps by mule, for safety’s sake.

Méchain publicly announced his intention to return. Indeed, he wrote to the prominent Milanese astronomer Barbera Oriani (whom Méchain had met a few years before in Paris) to tell him he would be leaving Genoa “on the thirteenth or perhaps the fifteenth of this month.” He asked Oriani to supply him with his most recent observations to carry across the frontier to Lalande. For his part, Méchain appended a gift offering, one of those gifts by which a savant elicits the free concession of scientific information from another: a summary of his own astronomical findings in Catalonia, including various eclipses, various stars, and a summary of the latitude data for Barcelona.

Oriani’s response was to rush down from Milan to visit Méchain before he left Italy. In honor of this visit, the Frenchman retrieved one of his repeating circles from the depot (even as Tranchot was packing their trunks) to demonstrate its marvelous capacities. They set up the apparatus on the terrace of the Hôtel du Grand Cerf—“one of the best hotels in town, magnificently situated right across from the sea”—and together took latitude measurements through the mid-October nights.

Oriani fell in love with the circle, and when his colleagues in Milan learned of its capabilities, they were eager to procure one of these marvels for themselves. The Milanese had been conducting their own geodetic survey, and Oriani suggested that he and Méchain connect the French and Italian grids via Genoa. “It is desirable that so beautiful an enterprise be undertaken.” Méchain wrote to Calon for his approval. To Méchain’s surprise Calon not only seconded the project, he even promised the Milanese a repeating circle of their own as soon as Lenoir could fashion one. The project would, after all, link the maps of France and Italy just as the French army was closing in on Turin to the immediate north. But there was to be no reprieve for Méchain; Calon still insisted that he report to Paris. “For you are not destined to return to Italy, but to extend the measure of the meridian in concert with Delambre.”

So Méchain concocted another plan to justify his sojourn in Genoa. (Never underestimate the ability of a scientist to generate new and interesting scientific questions when the need arises.) As Méchain pointed out, Genoa was near the 45-degree parallel, halfway between the equator and the pole. Bordeaux was not the only site suitable for a pendulum experiment to determine the length of the meter. If Calon would just send him the Observatory’s platinum-bob pendulum, Méchain would save the Commission the trouble of transporting a scientific team to Bordeaux. Or, alternatively, he might conduct observations at Genoa to supply new refraction corrections (and secretly resolve the discrepancy in his own Barcelona data).

In the end, the new French ambassador rescued Méchain by taking matters out of his hands. In a month on the job, Ambassador Villars had become familiar with Méchain’s vacillating ways, and Méchain had come to consider Villars “a friend of the arts and sciences.” The ambassador certainly proved a good friend to Méchain. Villars was savvy in the ways of officialdom. He advised Méchain to request further instructions from Paris—no one could ever fault a public servant for seeking to clarify his orders—and in the interim he would refuse to issue Méchain a passport, thereby taking responsibility for the delay upon his own head. All Méchain had to do was to write the request. On Monday morning, Villars told him that he expected the official request by two that afternoon, before the mail boat set out. When Méchain arrived at the post office at half past three—“I was still hesitating,” he admitted to Slop—the outgoing mail was already in the satchel, and Villars and the carrier were waiting impatiently. Villars snatched the letter out of Méchain’s hand and stuffed it in the satchel. “Your shilly-shallying is futile,” he told Méchain. “Your worries have no basis. Calm yourself and spend the rest of the afternoon with me.”

Villars’ maneuver worked. Tranchot stopped packing. And Méchain spent the rest of the winter on the Italian Riviera. “Our ambassador here,” he informed Oriani, “has required me to defer my departure.” In the meantime, he even took in some theater. While his traveling companions favored melodrama, Méchain preferred the classical theater, in which “order and tranquility reign, virtue is honored, and the happiness of all is every day more assured.” Some days, he even felt a degree of calm in his heart, only to suffer horrible presentiments of ruin at night. Folded inside a letter to Slop, he slipped a note labeled “For your eyes only.” “I do not believe I have given any cause for reproach,” he wrote, “but in the present circumstances, who can be sure he is safe from reproach, envy, enmity, and jealousy?” He had heard rumors that his enemies in Paris were conspiring to thwart his plans—although his wife seemed to be shielding him from these intrigues. “You see that I am well informed about events six hundred miles away and that my fears are not all chimeras.”

Today we have our own clinical terms for such psychological states. Méchain was depressive, we would say; he was paranoid, obsessive, passive-aggressive. No doubt this is true. Yet even feelings have their history, and Méchain was a man of the eighteenth century, a man who suffered from the exquisite malady known as melancholy. Melancholy was a complex affliction fueled by a disequilibrium of body and mind. It preyed on solitude and could encompass many moods. A voluptuous melancholy delighted in tombs and barren landscapes; nothing could be more delightful for an elegiac poet. A bitter misanthropic melancholy, such as beset Candide when he encountered the world’s cruelty, extinguished all hope in the future. And an anguished melancholy, oppressed by regrets too great to bear, might drive the mind to madness, or suicide.

Méchain exhibited all the melancholic symptoms featured in the nosology of Doctor Philippe Pinel, director at the Bicêtre asylum and Méchain’s colleague at the Academy: taciturnity, gloomy suspicion, monomania, and love of solitude. But if Méchain suffered from paralyzing doubt, it was because he faced an awful dilemma. If he trusted no one, it was because he did not trust himself. If he worried about conspiracies, it was because he was himself keeping a secret.


That winter, Méchain did not conduct the pendulum experiment. Nor did he measure geodetic triangles with the Milanese. A nameless colleague back in Paris was preventing Calon from sending him the pendulum, or so Méchain believed. As for the triangles linking Italy and France, Lenoir had yet to fashion another circle. At least Méchain had a neat solution for the latter problem. He asked Calon if he might sell one of his own circles to Oriani and take Lenoir’s new circle when it was ready. This would equip his team with hard currency and obviate the need to transport the circle home. To his surprise Calon again approved, and a week later Méchain was able to offer Oriani his choice of repeating circles: the one ruled in the traditional 360-degree scale, or the one ruled in the new 400-degree scale. Oriani chose the 360-degree circle and the two savants settled, somewhat awkwardly, on a price of 1,200 livres.

Méchain did conduct a few astronomical observations that winter from the bell tower of San Lorenzo cathedral, and at the famous Lanterna. One purpose of these observations was to test his conjecture about the refraction correction. The results were inconclusive. He also learned that Oriani intended to publish his Barcelona results, despite Méchain’s warning that they did not seem to follow the usual rule of refraction.

In late December Esteveny, the instrument-maker, decided to return to his family and business in Paris via the mail boat to Nice. The voyage was a month-long fiasco. A sudden storm forced all the passengers to toss their belongings into the sea, and Esteveny arrived in France with only the shirt on his back. Then, as he disembarked, the French authorities arrested him as a returning émigré. Freed on the say-so of the captain, he was hampered at every stage of his overland trip by a lack of hard currency. When reports of his unhappy voyage filtered back to Méchain, it only confirmed the latter in his caution. Just imagine what would have happened had Méchain entrusted Esteveny with his precious instruments, or worse, with his irreplaceable data!

Méchain still had Tranchot, though the two men had grown increasingly estranged. They no longer lodged at the same inn, nor spent time in one another’s company. Both men came from the lower strata of the Ancien Régime, yet neither had found his place in the new. Tranchot was a military engineer, a man of action, robust and confident. He was a bachelor who had yet to draw upon his expedition salary. He wrote short frank letters in a neat square hand. Yet he aspired to the trappings of polite society. During his twenty years in Corsica, he had amassed a small collection of minerals and fossils, and during his sojourn in Italy he added petrified fish, feldspar, and crystals “very sought after by connoisseurs in Paris.”

Each man operated according to his own exacting conscience. Tranchot had his military patriotism and Méchain his passionate rectitude. Perhaps this was why they found one another so exasperating. Tranchot considered Méchain’s delays a dereliction of duty, and his vacillation pathetic. When Méchain announced for the umpteenth time that they would soon be leaving Genoa, the engineer wryly commented, “According to Monsieur Méchain we will be leaving after Easter, but I don’t yet know if that is really true.”

For his part, Méchain swore he bore no enmity toward his adjutant, despite his suspicion that Tranchot was plotting to usurp his leadership. Tranchot’s impatience was a continual reproach, his competence a continual challenge.

[G]iven what I have seen since our departure from Barcelona, I would be deluding myself to count any longer on his friendship, affection, or trust. Since arriving here he has expressed himself all too clearly, and I am not so stupid as to expect any resumption of his previous feelings. But honesty and probity have always been my rules of conduct with him, as with others.

Yet Méchain had to wonder whether Tranchot knew his secret. And whether he might give it away.

As spring approached, and the season for geodetic campaigning drew near, Calon tried again to lure Méchain back to France. He tried to make the prospect appealing to Méchain’s honor. Many of France’s most illustrious savants had signed onto his new geographic enterprise, he noted: Lalande, Delambre, Laplace, all his old colleagues. “You will not find yourself a stranger in the presence of those who share your labor,” he said—not realizing, of course, that these were the very people Méchain feared would unmask his error.

Not until the law of 18 germinal III (April 7, 1795) formally revived the meridian survey and restored Delambre to the mission did Méchain pack in earnest to leave Genoa—though even at this last minute he claimed intrigues in the capital jeopardized the expedition. Again he began making excuses not to return. This time, however, he could no longer postpone his departure. To fail to leave now would cost him his position and his family’s sole means of support. In his last letter to Slop he even summoned a stoic courage: “But the die is cast, and I will attempt the adventure.” In late April, he boarded the mail boat for Marseille with his one remaining circle and his one remaining assistant.

Even as Méchain left Genoa, the Revolutionary Republic moved against the patrician city. Tranchot had been tracking the war’s progress. In November, he boasted of French victories that would oblige the enemy to recognize the sovereignty of the French people. Nearer to Genoa, plans were afoot to land 20,000 French soldiers behind Austrian lines. In mid-March, Tranchot climbed the hills above town to watch the French fleet engage the English navy. The guns sounded from four in the morning until three-thirty in the afternoon, and Tranchot initially reported a French victory, one which he hoped would oblige the Genovese patricians to abandon their cowardly neutrality. Then, when he discovered that the battle had actually forced the French to retreat to Toulon, he dismissed this as yet another betrayal of France from within. Oh when, Tranchot wondered, would France find a hero to right its reversals?

Within a year Bonaparte led his armies across Italy in one of the most dramatic military campaigns of modern history. In April 1796 his army occupied Genoa, the city he had judged ripe for the picking during his visit of 1794. In May 1796 Milan opened its gates to the conqueror, only to have the city pillaged by French troops—though Napoleon assured the astronomer Oriani that men of science would gain from his conquest: “All men of genius, all those who have achieved distinction in the Republic of Science, are French, no matter what their native land.” In June 1796, French troops occupied Livorno and Pisa, where Slop’s son went to work as an agent of the French Republic.


When Méchain and Tranchot arrived in Marseille by mail boat in the spring of 1795, Méchain’s colleagues had every reason to think he would proceed immediately to Paris to consult with them before resuming his mission. Paris was only a week’s ride north by carriage. Or perhaps he would prefer to head directly to Perpignan to pick up his triangulations where he had left off. Perpignan was only a few days’ ride to the west. Yet Méchain holed up at Marseille for the next five months. During those summer months, the best season for geodetic observations, Delambre measured the entire sector from Orléans to Bourges.

Méchain’s dithering infuriated Tranchot, exasperated Calon, and baffled his colleagues. To prompt him to resume the mission, Calon sent Esteveny down to rejoin him in Marseille, as well as two new assistants to replace Tranchot. The French army was desperate for surveyors, and Tranchot was one of the nation’s most experienced military cartographers. Calon wanted him to triangulate the mountainous frontier along the Swiss-Italian border, where Napoleon was preparing his invasion.

Privately, Méchain admitted that Tranchot no longer wished to serve under him. “I know he does not want to be under my direct authority, and may God grant his wish!” Yet he did not want to forgo Tranchot’s services either. Nor can he have been eager to have his assistant—the one person on earth who might have guessed his secret—far out of sight. So when his new assistants arrived in Marseille, he refused to release the engineer. He wrote to Lalande that Calon wanted to deprive him of his most capable aide. “We got on well together while on mission; he assisted me marvelously in my astronomical observations.” He wrote to Delambre that without Tranchot his progress would be slow. Admittedly, a second observer might seem superfluous now that he had only one repeating circle. But Calon himself had approved the sale of the other circle to the Milanese, and it was not Méchain’s fault that Lenoir had yet to supply a replacement. In mid-August, Calon relented. “I must at last defer to your wish that I not separate you and Tranchot. You may use him as you judge most convenient.”

This suited Méchain. With Tranchot under his direct authority, and with only one circle available, he controlled both the observations and the data.

Tranchot, however, could hardly have been more disappointed. Instead of commanding his own survey, he was once again under the authority of the vacillating, exasperating savant. He obeyed Calon’s orders—it was wartime and he was an officer—but he insisted that the expedition get underway. He requested permission to rent a coach and driver at 10 francs a day to carry the team overland to Perpignan. Yet, after approving this plan, Méchain balked at boarding the carriage and instead booked a passage on a naval vessel traveling to the port of Sette. (Four years later, their expedition done, the driver of the Marseille coach turned up in Paris with the signed contract to collect his 15,000 francs in accumulated daily fees, and Delambre was obliged to bargain his bill down to the cost of a new coach instead.) In late August 1795, Méchain and his team sailed from Marseille to the port of Sette. From Sette the team was rowed in longboats onto the beach at Canet. And from there soldiers were commandeered to haul their equipment four miles across the flatlands to Perpignan. After a hiatus of two and a half years, Méchain had at last resumed the measurement of the meridian.

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