by Ken Alder
It was an ideal spot from which to measure the world. Delambre obtained permission to build a temporary four-windowed observatory high up in the cupola where he could work sheltered from the icy winds. The architect even talked of building a permanent astronomical observatory in the hollowed-out half-globe under Fame’s feet, thereby “uniting the beauty of art with usefulness to science.” This goal was consonant with the building’s greater dedication to the triumph of Truth over Falsehood. In the pediment over the mausoleum’s motto—“AUX GRANDS HOMMES, LA PATRIE RECONNAISSANTE” (“TO GREAT MEN, A GRATEFUL NATION”)—a frieze depicted the sort of heroes entitled to admittance. As the architect explained, it was by “the conquest of Error” that Genius, in the guise of a robust young man, might manfully seize the laurels of immortal remembrance.
Thus far, the men deemed worthy of being considered for this honor were Mirabeau, the nation’s greatest politician; Voltaire, its greatest literary lion; Rousseau, its greatest political thinker; and Descartes, its greatest savant. Mirabeau was the first actually to be buried there. Soon after, Voltaire’s remains were borne to the Panthéon in a stately procession witnessed by a hundred thousand spectators. And preparations were now underway to accord Rousseau the same honor. But one man’s hero is another man’s scoundrel, and just as Delambre returned to the capital, a young radical politician named Maximilien Robespierre demanded that Mirabeau be disinterred for not living up to Republican ideals. The decision on Descartes was postponed. In the meantime, the interior of the Panthéon remained stacked with provincial bushels, pints, and pound weights, sent in for comparison with the new metric measures.
In January and February 1793, during the month it took the architects to build Delambre his neat little crow’s-nest observatory 227 feet above the pavement, the king of France was tried, judged, and executed, war was declared on Great Britain, and food riots ravaged Paris. Then from February to March, while Delambre climbed the cupola daily to triangulate all the stations surrounding the capital, war was declared against Spain, the west of France rose up in a counterrevolution, and preparations began in the National Assembly to create a Committee of Public Safety to organize the nation’s defense. His was an admirable perch above a city in turmoil. Delambre sighted the new semaphore telegraph station on Montmartre; it could relay battle news from the northern front in thirty minutes. He sighted his own personal observatory at 1, rue de Paradis. He sighted the stations at Saint-Martin-du-Tertre, Dammartin, Belle-Assise, and Montlhéry. When he came down from the Panthéon for the last time on March 9, 1793, he had finally completed the stretch of the meridian that traversed the area around Paris. This represented less than one-tenth of his assigned sector, whereas Méchain in that time had completed nearly half his sector, and was wrapping up his latitude measurements at Mont-Jouy.
Delambre wrote immediately to Méchain to tell him where things stood in the north. Try as they might, his experience of the past year gave him little reason to hope that they would be able to link their triangles this year. “Too many obstacles will get in our way,” he predicted. Already the new administrators of radical Paris were ignoring his request for a passport, despite the proclamation of the National Assembly approving their mission. (He apologized for the fact that the proclamation listed his name first, but “I was not there to tell them that your entry into the Academy predates mine.”) “Farewell, my dear colleague. I wish you health, fortitude, and patience. Be assured of my sincere friendship.” By the time the letter arrived, Méchain’s progress had also come to a halt; he was confined to bed, immobilized, out of funds, and detained by Spanish law.
The French government was running out of patience. Several years had passed since the Academy had first promised that the survey of the meridian would be done within a year. The actual expedition had been underway for a year now, yet both Delambre and Méchain had stalled far short of their rendezvous point. Various proposals for the reform of measures had been in circulation since the earliest days of the Revolution, and the radical legislature was impatient to bring France into the metric age. Officials had begun to ask if the meridian expedition was really worth the wait. It was a question that some people had been asking from the start.
Paradoxically, one of these people was Jérôme Lalande, the savant who had given both Delambre and Méchain their start in astronomy. Lalande had been the first person to take advantage of the French Revolution to place before the nation’s representatives a proposal to reform its weights and measures. In April 1789—before the taking of the Bastille, even before the representatives summoned by the king had constituted themselves as the National Assembly—Lalande had denounced the “unconscionable and multiple abuses of the diversity of measures,” and urged the representatives to create a uniform system of measures by simply declaring the Paris measures to be the national standard. In this speech he also demanded a moratorium on the slave trade, the substitution of free public education for the Ancien Régime’s religious schools, and the “liberation” of all monks and nuns.
Lalande had always been a man ahead of his time, yet curiously Ancien Régime in his obsessions. He was not only France’s foremost astronomer, he was its foremost popularizer of science—in an age when the popularization of science was the principal weapon against intolerance, superstition, and injustice. Lalande had also trained with the Jesuits and had nearly taken orders, only to become France’s most notorious atheist. His father, a Burgundian postmaster and tobacco merchant, sent him to Paris to study law, but every night he slipped out of his student chambers in the Hôtel de Cluny to join the astronomers on their rooftop observatory. In 1751, when Lalande was nineteen, his mentor sent him on an astronomical mission to Berlin to help determine, by parallax, the distance from the earth to the moon. In Berlin, Lalande dined with Frederick the Great (Europe’s greatest benign despot), lodged with Leonhard Euler (its greatest mathematician), and conversed with Voltaire (its greatest wit). On his return to Paris in 1753, he was unanimously elected to the French Academy of Sciences. He was twenty-one years old.
Immediately he was plunged into controversy. Lalande did not agree with his mentor about how to correct his results for the shape of the earth. Lalande was vindicated by the Academy, and his mentor refused to speak to him again. Polemics and controversy pursued him for the next fifty years.
In 1773 a rumor circulated through Paris: Lalande had calculated that a comet might swing close enough to the earth in 1789 to drive the seas from their beds and devastate the earth. The Archbishop of Paris recommended forty hours of prayer and the kingdom’s police chief asked the Academy of Sciences to repudiate Lalande’s findings. The Academy replied that it could not repudiate the laws of astronomy. Then, when Lalande finally published the paper, he gave such a low estimate of the odds of disaster (about one chance in 64,000) that many readers assumed the government had suppressed the truth. In the countryside, word of the impending apocalypse caused public repentances and (supposedly) stillbirths. (If only Lalande had predicted the end of the kingdom instead of the end of the world, one wag later remarked, he would have been the greatest prognosticator of the century.) Some good at least had come of the panic, according to Condorcet. Court ladies and market women had confessed their sins, and the bakeries had experienced a run on unleavened bread, boosting the local economy. Where the laity had once heeded necromancers, they now hearkened to scientific prognosticators. “The time of prophets has passed; that of dupes will never end.”
Lalande had an insatiable thirst for fame. He cultivated friendships with the great minds of the age and published incessantly. He wrote about paper and platinum, canals and calendars, music and morals. He wrote eulogies for the dead, tributes to the living (including his own estranged mentor), and predictions of astronomical events to come. He was a prodigious travel writer. In Italy he catalogued antiquities, met the Pope, and lobbied him to remove the writings of Copernicus and Galileo from the Index of prohibited books. In England he visited the Greenwich Observatory,
exchanged pleasantries with King George III, and helped smuggle out the first description of Harrison’s famous chronometer, designed to determine longitude at sea. He dismissed balloon flight as impossible; then, when the Montgolfiers proved him wrong, claimed he had predicted success and demanded to be taken on the next flight. Later, he set out on a three-hundred-mile balloon voyage to attend a scientific conference in Germany, got as far as the Bois de Boulogne, and declared victory in the form of bad verse. He even wrote the first history of the secretive International Brotherhood of Masons and cofounded its infamous Lodge of the Nine Sisters, which claimed as brothers such luminaries as Condorcet, Danton, Diderot, d’Alembert, Voltaire, and Benjamin Franklin.
Such boundless enthusiasm always attracts naysayers—or at least it does in France. One wit diagnosed Lalande as suffering from “dropsy of celebrity.” Lalande confessed the fault, but excused himself on the basis of his “innate truthfulness and love of virtue.” Eventually, his mania for fame itself became a theme in the commentaries on his doings, generating still more publicity. Voltaire praised him “for having found the secret of making the truth as interesting as a novel,” and the poet even knocked off a couplet in the astronomer’s honor.
Your glory is known throughout the universe,
And only when it ends, will your name disperse.
As for his notorious taste for insects and bugs, he reported that spiders had the flavor of fine hazelnuts, whereas caterpillars tasted more like peaches. He dined on the latter regularly at a friend’s house, directly after Saturday meetings of the Academy. The friend noted, “As my home opened directly onto a fine garden, Lalande could easily find enough caterpillars there to appease the first pangs of his hunger; but as my wife liked to do things properly, she would gather a goodly number in the afternoon so she might serve them to him as soon as he arrived. Because I always offered him my portion of this ragout, I cannot tell you except by hearsay how they tasted.”
He was a supremely ugly man, and proud of it. His eggplant-shaped skull and shock of straggly hair trailing behind like a comet’s tail made him a favorite of portraitists and caricaturists. He claimed to stand five feet tall but, precise as he was at calculating the heights of stars, he seems to have exaggerated his own altitude on earth. He loved women, especially brilliant women, and promoted them in both word and deed. His longtime mistress, Louise-Elisabeth-Félicité du Piery, was the first woman to teach astronomy in Paris. He sang the praises of women astronomers such as Caroline Herschel and Madame Lepaute. When he was appointed director of the Collège de France during the Revolution, his first official act was to open classes to female students. He dedicated his Ladies’ Astronomy to his mistress, and this serious primer, with its examples of active women researchers, was still being published sixty years later.
Yet he loved women in ways they did not always find agreeable. He never married, though he bragged of refusing advantageous offers. When at the age of forty-four he finally did propose, the fourteen-year-old girl refused him. He had a salacious turn of mind. He noted in his diary that “Monsieur de V———loved his pretty wife so much that he invited the most agreeable young men to his home and let them have sex with her in front of him; Helvetius was among them.” He made an unwelcome pass at the gifted young mathematician Sophie Germain and wrote an abject apology the next morning—including an apology for slighting her scientific knowledge. As he liked to tell pretty women: “You have the power to make me happy, but not the power to make me unhappy.” He loved women, he said, but not so much as to distract him from his greatest love: the stars.
JÉRÔME LALANDE
This pastel portrait of Lalande was drawn by Joseph Ducreux in 1802, when the astronomer was seventy years old. It shows him in the uniform of the new post-Revolutionary Academy of Sciences. (From the Musée de Versailles, Réunion des Musées Nationaux; photograph by Art Resource, New York)
In short, he was a shameless self-promoter, a trait which made him especially effective at the calling he prized above all others: teaching. Lalande was a gifted pedagogue, a missionary for his science. His Astronomy became the field’s standard textbook. His lectures at the Collège de France attracted two hundred students, with auditors from across Europe, who then joined his worldwide network of correspondents. By the 1780s, he had trained France’s next generation of astronomers, among them Delambre and Méchain, putting them all to work in his scientific workshop, the Lalande family enterprise.
For Lalande, astronomy was the family business. He had brought his young cousin Lefrançais in from the country, adopted him as his nephew, trained him in astronomy, and then married him to his illegitimate fifteen-year-old daughter, Marie-Jeanne-Amélie Harlay, whom he had trained in mathematics to calculate his celestial data. He was very attached to his “niece” and “nephew”—as he called them—and easily moved to tears where they were concerned. Amélie performed the bulk of the calculations for the massive navigation tables he published in 1793, “tiresome calculations, but here acquiring a more noble character by the aid they offer navigators, connecting remote parts of the universe.” He could be a hard taskmaster. He complained to his mistress, “When I’m not around, my shop goes on holiday.” “Wash out my nephew’s head if he’s not working.” At the start of the Revolution, he announced a new goal for his astronomical family: a monumental catalogue of thirty thousand stars that would surpass the old celestial survey. His students were likewise expected to contribute to this enterprise.
Méchain had already done the lion’s share of the work for the second edition of Lalande’s Astronomy, which appeared in 1781. The prize competition of the Academy that year was to chart the trajectory of the comet Lalande had predicted might devastate the earth in 1789. Méchain wrote a paper that showed that his mentor had erred by confusing the appearances of two different comets. When the Academy of Sciences awarded its 1781 prize to Méchain, Lalande had the good grace to be pleased. In 1782 he got Méchain elected to the Academy, then looked around for a new recruit.
In 1783 Delambre began supplying Lalande with data for his third edition of Astronomy, and Lalande soon ran out of words of praise for his abilities. “Monsieur Delambre . . . is currently the most able astronomer of any country in the world. . . . We must encourage so valuable a recruit, and bind him to a science in which he performs prodigious feats without hope of any position or advantage.” Delambre’s first astronomical coup likewise came at his mentor’s expense. In 1786, he was one of only two astronomers in Paris to record the last flicker of Mercury during the planet’s transit across the sun. This was not merely an observational coup, it was a theoretical triumph. As was his custom, Lalande had publicized the time of the planet’s transit in advance. However, the overnight clouds persisted beyond the appointed hour, and the country’s leading astronomers all quit their posts. When the clouds broke at eight in the morning, Delambre, still at his telescope, saw Mercury exit the sun forty minutes after Lalande had predicted it would. The only other observer to capture the transit had been looking for sunspots. Delambre had stayed at his post because he doubted Lalande’s calculations.
For all his boundless vanity, Lalande never took offense when his students contradicted him. “I am waterproof to insults, and a sponge for praise,” he said. Perhaps he remembered the repudiation he had suffered at the hands of his own maître. In any case, there was work enough in heaven for all. Science was a collective triumph, even if the race was run by men hungry for personal fame. He presented Delambre’s Mercury results at the next meeting of the Academy of Sciences—with Delambre in attendance—then promptly used the data to update his own tables.
The Mercury coup exhibited the scientific virtues that would sustain Delambre on his seven-year pursuit of the meridian: his patience and perseverance, his precision and skepticism, his ability to marry observation and theory, and his confident willingness to show up his elders. Méchain, despite tremendous preparation, had missed the observation of Mercury. As he noted ruefully, he h
ad believed Lalande’s prediction.
Delambre also knew how to parlay success into greater opportunities. At that same Academy meeting, Pierre-Simon Laplace presented another installment of his System of the World, his life’s work synthesizing Newton’s cosmology. Laplace was the same age as Delambre, but he was already his era’s leading physicist, a theoretician who claimed that were the position and motion of all the world’s particles known, the entire future of the universe could be predicted by a being of infinite intelligence. This particular paper refined a technique for tracking the perturbations which one planet caused in the orbit of another. Delambre was dazzled by the ability to calculate orbits so precisely. Several years before, Méchain had supplied Laplace with some preliminary data for the newly discovered planet of Uranus. Delambre now proposed to confirm Laplace’s theory using Uranus. This involved tremendous labor: for nearly two years Delambre observed at night for eight hours at a stretch, then spent equal time on daytime calculations. His achievement did not go unrewarded. At the prompting of Laplace and Lalande, the Academy of Sciences announced that the topic for its 1789 prize competition would focus on the precise calculation of the orbit of Uranus. As Delambre remarked to a friend, he could be sure his memoir would be the best, since it was the only one submitted. The prize committee consisted of Cassini, Lalande, and Méchain. As Delambre privately admitted, it would have been hard to find judges more “favorably disposed.” In the report which awarded his student the prize, Lalande praised Delambre as “an astronomer of wisdom and fortitude, able to review 130 years of astronomical observations, assess their inadequacies, and extract their value.”
