The Day the World Discovered the Sun (7 page)

It all had started on St. Helena. The island was something close to sacred ground for men like Maskelyne who admired Halley and devoted their careers to carrying his legacy forward.

So Maskelyne drank down his failures at St. Helena—he'd also tried and failed, using a different method, to measure the distance to the star Sirius—and, together with Mason, prepared to return home.

Some might have crumpled at such a low ebb. But Maskelyne didn't even idle aboard ship. His and Mason's passage to England aboard the East India clipper
Warwick
(escorted by the 24-gun naval frigate
Terpsichore
) would be their teaching lab. Maskelyne and Mason were, after all, experts in the science that was primed to solve the greatest earthly problem known to every explorer and naval captain of the day.

Maskelyne and Mason spent their nights, dimly lit by the phosphorescent glow of the Ethiopic Sea (today's southern Atlantic), instructing
Warwick's
officers how to measure their longitude onboard a moving ship. Maskelyne had with him a new set of nautical tables that predicted the moon's position in the sky with uncanny accuracy. Using a ship's quadrant—an iconic mariner's device with spyglass on top and wooden or metal wedge of a circle hanging beneath it—Maskelyne gave some of the first master classes on navigating by lunars. His students learned accurate shipboard measurements of the moon's angular separation from the sun (during the day) and known bright stars (at night).
²⁹
And, equally important, Maskelyne taught the laborious calculations needed to turn these measurements into longitude. (Grinding out a single longitude value via the lunar method could take up to four hours of pencil work.) But Maskelyne and his new students proved, sometimes multiple times per day, that they could reckon their longitude to within a degree—which translated to forty nautical miles at the latitude of the English Channel.

These were the kind of results that might win the coveted Longitude Prize.

On May 14, 1762, the
Warwick
anchored at Plymouth, returning Mason to the site of his dressing down by the Royal Society. But the private humiliation he and Dixon faced the year before paled in comparison to the competitive kick in the hindquarters that Mason and Maskelyne had received in their absence.

As the astronomers offloaded their gear onto English soil, word began spreading around the docks of another ship that had anchored at Portsmouth two months before. The sloop
Merlin
had reached port on March 27, carrying onboard a watchmaker named William Harrison and the astronomer John Robison. Harrison had traveled to Jamaica and back testing his father's design of a compact, spring-wound maritime clock. If Harrison's machine succeeded as stunningly well as its promoters claimed, it could cast the entire future of lunar navigation—and, with it, many astronomers' well-funded careers—to the westerly winds.

The cloud bank to the east glowed red. Jean-Baptiste Chappe d'Auteroche had been living at his mountaintop observatory, avoiding contact with the superstitious townsfolk and instead looking to the skies. His lot, he'd surmised, was not to make inroads with the locals but rather, as a fellow French philosophe put it, to make “a communication of flying bridges, as it were, that reunite one continent with another and pursue all the tracks of the Sun.”
¹

Three days before, Chappe had pointed his nineteen-foot telescope at a solar eclipse, recording in his logbook the exact moment when the eclipse ended. His pendulum clock—which he'd previously set to noon when the sun reached its highest altitude in the sky—read 6:11
AM
and 4 seconds. He'd already calculated that the same solar eclipse would be visible in St. Petersburg as well. So when he later returned through Russia's capital city en route to Paris, Chappe could then compare notes with observers there. Since the eclipse ended at the same instant, whether seen from Tobolsk or St. Petersburg, the difference in time between these geographically separated measurements was exactly the difference
in longitude between the locales. Chappe derived that Tobolsk was 65.8490 degrees east of the National Observatory in Paris. (Today, Chappe's longitude would be written as 68.1862 degrees east of the prime meridian, the British Royal Observatory in Greenwich, England. By either standard, Chappe's error was an impressive 0.0719 degrees or 4.3 arc minutes—translating to 3 miles at Tobolsk's latitude.)

The night before the transit, all looked calm. “The sky was clear,” Chappe recalled. “The sun sunk below the horizon free from all vapors. The mild glimmering of the twilight and the perfect stillness of the universe completed my satisfaction and added to the serenity of my mind.”

By morning, however, the 4:30 sunrise had brought a dark veil. Clouds loitered. As the increasingly cloudy and sleepless night progressed, Chappe paced the observatory floor. His assistants, whom Chappe had woken earlier in the night, left their master alone—knowing they'd only be needed if clear skies returned. “I found myself relieved by their absence,” Chappe wrote.

Soon after dawn, Chappe heard a commotion outside. Tobolsk's governor, the local archbishop, and some nobles had assembled at the new observatory to take in the heavenly spectacle.
²
The first light of day shone upon the French visitor whose anxiety grew with each troubled glance at the clouded-over sky.

“The idea of returning to France, after a fruitless voyage, of having exposed myself in vain to a variety of dangers,” he recalled, “[with every] expectation of success, which I was now deprived of by a cloud . . . threw me into such a situation as can only be felt.”

Chappe had instructed his assistants to set up a tent outside the observatory with the secondary telescope. The arrangement provided all they'd need to view the transit—but still permit Chappe to perform his own delicate observations with the privacy he demanded.

As the dawn's blush gave way to early morning light, an easterly wind peeled back the top layers obscuring the sun. And with the increasing transparency, the mood both inside the observatory and in the nearby
tent lightened. “The clouds began to exhibit a whitish color, which grew brighter at every instant,” Chappe wrote. “A pleasing satisfaction diffused itself through all my frame and inspired me with a new kind of life.”

To everyone's pleasant surprise, the residents of Tobolsk—so vocal in their opposition to the Frenchman's entourage weeks before—had shut themselves up in their houses and churches, some fearing God's imminent wrath. Today, the armed guards assigned to protect Chappe proved an unnecessary precaution. Chappe instead enlisted their help in moving his nineteen-foot telescope out onto the lawn.

Doomsday had been postponed. Instead, the morning of June 6 brought a clear patch through which Chappe could view unobstructed the first hints of a tiny black sphere piercing the sun's sacrosanct disk. The assembled crowd in the nearby tent now had something to see.

Henceforth no excuses remained. Heartbeats quickened as Chappe cued his interpreter inside the observatory to shout out every second of every minute on the pendulum clock. A stream of numbers cut the hush with metronomic quickness. “Cinqante-cinq minutes et un . . . deux . . . trois . . . quatre . . .”

The seven o'clock hour approached as Chappe adjusted his telescope. Like a smooth, circular pebble descending into a thick fluid, Venus began crossing the solar limb. Eighteen minutes after Venus first excited the assembled crowd with its initial appearance, the first crucial moment of its solar transit approached—when the sun had enveloped the entirety of Venus's shadow. No words the interpreter had ever said meant more to Chappe than the sequence of numbers he shouted through the observatory door. “Vingt-quatre . . . vingt-cinq . . . vingt-six . . .”

At 7:00
AM
and 28 seconds, Chappe recorded in his logbook the moment of internal contact between Venus and the sun. “I . . . felt an inward persuasion of the accuracy of my process,” Chappe recorded. “Pleasures of the like nature may sometimes be experienced. But at this instant, I truly enjoyed that of my observation and was delighted with the hopes of its being still useful to posterity when I had quitted this life.”

Many other observers of the 1761 transit reported difficulty recognizing the instant of interior contact, elongating the measure of a moment into a guessing game extended over tens of seconds. This surprise phenomenon, ruining many otherwise useful transit observations, results from an optical illusion that makes the sun's limb briefly pucker inward with a plasticity that appears to connect it with Venus's distorted disk. Chappe, on the other hand, reports no problems with what was later dubbed the “black drop effect.”

The aromatic musk of Russian tea—hints of honey and Spanish pepper—spiced the air of this increasingly beneficent morning. Chappe had refused dinner the night before, and the twelve or more hours since his last meal would have left the explorer with little more than adrenaline to fuel him. The city's nobles, gathered around the nearby tent, provided a counterpoint. Spirits like bilberry wine and quas—a commonplace Russian drink made of fermented meal and malt
³
—likely blurred these momentous few hours into pleasantry while delicacies like caviar and roasted quail tempted hungry men in Chappe's party to join in. (“All these [Siberian game] birds,” Chappe grumbled, “have a disagreeable fishy taste.”)

The sun continued rising, and the clouds continued to clear. Around 10:00
AM
, Venus had reached the halfway point in its transsolar journey. At the exact median, Chappe tended to the second smaller telescope to make a different kind of measurement. As an independent check against the transit's time records, he also measured the separation between the nearest edge of Venus and the sun's enveloping arc. His ten-foot telescope, in less demand after drink and disinterest had peeled away some of the observatory's guests, made its 3,000-mile journey to yield one crucial number of angular distance. Inside the smaller telescope's eyepiece a translucent set of hash marks provided the ruler that yielded 6 arc minutes and 2 arc seconds of angular separation between planet and star at the transit's halfway point. And to check his check, Chappe also measured out the entire diameter of the sun: just over one-half of a degree—31 arc minutes and 37 arc seconds.

Now measured as if for a new outfit, a star ascended. It gave day to the earth, as it always does. But on this day its closest watchers had reached into the beyond for their first grasp at a universe of knowable depth.

The lecture everyone had come to see concerned a tiny planet passing in front of the sun.
⁴
But from all the chatter in the room, a casual observer might think the sun had gone into permanent eclipse. A fortnight before, fifty-two-year-old Elizabeth Petrovna, empress of Russia, had died.

Elizabeth had reigned for twenty years over relative domestic calm during an age of nearly nonstop European war. She was widely beloved, both at court and in the populace at large. She was, nevertheless, every bit a Russian czarina too. Her extravagances were legend: 15,000 ball gowns and thousands of pairs of shoes. And not a few lovers on the side. She also brooked no personal criticism. In his memoirs of the Siberian voyage, Chappe tells a chilling story of Elizabethan retribution against courtly ladies who had conspired against the empress—although some historians suspect the women were in fact only guilty of talking too freely of Elizabeth's amorous activities. In a riveting story that was cited and re-recounted for generations to come, including in the legendary
Life of Samuel Johnson
, Chappe wrote:

Madame Lapouchin was one of the finest women belonging to the court of the Empress Elizabeth . . . [and] was condemned by the Empress Elizabeth to undergo the punishment of the knout. She appeared at the place of execution in a genteel undress, which contributed still to heighten her beauty. . . . One of the executioners . . . then took a kind of whip called knout,
made of a long strap of leather prepared for this purpose. He then retreated a few steps, measuring the requisite distance with a steady eye. And leaping backwards gave a stroke with the end of the whip so as to carry away a slip of skin from the neck to the bottom of the back. Then striking his feet against the ground he took his aim for applying a second blow parallel to the former. So that in a few moments all the skin of her back was cut away in small slips, most of which remained hanging to the shift. Her tongue was cut out immediately after, and she was directly banished to Siberia.
⁵

Despite a brutality that matched her vanity, the empress had endeavored to make St. Petersburg a European capital of high culture—graced with her characteristic enchantment of French culture, in particular. So although some Russian academy members had resisted supporting Chappe's Siberian voyage, the academy nevertheless offered the visiting Frenchman the opportunity to discuss his work and findings.

Still, one might forgive Chappe's audience for a level of distraction higher than any scholarly norm. The late empress had also left behind an empire apprehensive of its future. Now holding the scepter of power in Elizabeth's wake was her reviled nephew Peter—“the most imbecile prince that ever ascended the throne of a vast empire,” as one contemporary journalist described his public reputation.
⁶
Elizabeth's armies—allied with France and Austria against Britain and Prussia—had beaten back the Prussian army to the point that total victory was thought to be close at hand. But Peter so worshiped the Prussian commander Frederick the Great that rumors were spreading that the new Russian emperor wanted to completely withdraw Russia from the war, consequences be damned.