by David Baron
Newcomb thrived among this merry band of geniuses and misfits. Although calculating orbits was simple in principle—merely a matter of applying Newton’s law of universal gravitation—the task was, in practice, mind-bogglingly difficult. Planets do not blithely revolve around the sun along perfect, elliptical paths; they meander because, as Newton had written, “the orbit of any one planet depends on the combined motion of all the planets.” Jupiter pulls on Saturn. Earth tugs on Mars. To derive orbits, Newcomb and his colleagues had to calculate this complex, gravitational dance. “To this work I was especially attracted because its preparation seemed to me to embody the highest intellectual power to which man had ever attained,” Newcomb wrote.
Twenty years after beginning his career with the Nautical Almanac, then leaving for a long stint at the U.S. Naval Observatory, Newcomb triumphantly returned as the man in charge. In 1877, early in the administration of Republican President Rutherford B. Hayes (whom Democrats mocked as “His Fraudulency” given the disputed election of 1876, which Hayes had won despite losing the popular vote), Newcomb was appointed superintendent of the Nautical Almanac. The office, now in Washington, occupied what Newcomb called “a rather dilapidated old dwelling-house . . . on the border line between a slum and the lowest order of respectability,” but he could not have been happier. He had become the modern equivalent of the ancient court astronomer. It was his job, on behalf of the U.S. government, to divine the motions of the celestial spheres, and that included predicting eclipses.
“I WISH TO ISSUE some information respecting the total eclipse of July 29th next, perhaps a chart,” Newcomb wrote in January 1878 to his assistant George W. Hill, a brilliant computer but socially awkward man. (“Professor Newcomb says Mr. Hill is the finest mathematician in America if not in the world, but he can’t say two words,” a young woman confided to her diary after meeting the timid scientist.) Newcomb instructed Hill “to compute the central line and limits of totality.” After plotting the path on a series of maps, Newcomb published them with accompanying text in a special eclipse bulletin.
“During its progress, the dark shadow of the moon will first strike the earth in the province of Irkoutsk, Siberia,” Newcomb wrote. “Its course will at first be east-northeast, but will gradually change to east, and, after leaving Asia, to southeast.” The maps showed the path in detail where it traversed the United States along a gently curved line. “In this country it will sweep over the western end of Montana Territory, the Yellowstone National Park, Wyoming Territory, Denver, Colorado, and Northern and Eastern Texas, entering the Gulf of Mexico between New Orleans and Galveston.” Newcomb explained that Americans outside of the path, which was only 116 miles wide, would witness a partial eclipse. He then added this appeal: “Total eclipses of the sun are so rare at any one point that the opportunities they offer for studying the attendant phenomena should be utilized in every way.”
TRACK OF LUNAR SHADOW.
What Newcomb meant he explained more fully in Popular Astronomy, his new book, which—despite a luke-warm review from Maria Mitchell—sold sensationally, enjoying multiple editions. “Total eclipses of the sun afford very rare and highly prized opportunities for studying the operations going on around that luminary,” Newcomb wrote. “[A]s the last ray of sunlight vanishes, a scene of unexampled beauty, grandeur, and impressiveness breaks upon the view. The globe of the moon, black as ink, is seen as if it were hanging in mid-air, surrounded by a crown of soft, silvery light, like that which the old painters used to depict around the heads of saints.” Astronomers called this glowing halo the corona, and while it is now known to be the sun’s extremely hot outer atmosphere, its nature remained a mystery in Newcomb’s day. At one time, scientists had thought it might be the moon’s atmosphere backlit by the sun, or perhaps it was merely an illusion produced by sunlight passing through the earth’s atmosphere. By 1878, the corona was generally accepted as a true solar phenomenon, caused by something that surrounded the sun. But what? A massive envelope of luminous gas? A cloud of dust particles that reflected sunlight? A swarm of meteors?
Other odd sights also appeared during a total solar eclipse. “Besides this ‘corona,’ tongues of rose-colored flame of the most fantastic forms shoot out from various points around the edge of the lunar disk,” Newcomb wrote. “They are known by the several names of ‘flames,’ ‘prominences,’ and ‘protuberances.’ ” These too had perplexed astronomers.
Ultimately what scientists were trying to unravel was the enigma of the sun itself. What was it made of? What fueled its colossal fires? The phenomena seen at total eclipses provided clues. “We thus have the seeming paradox,” Newcomb wrote in 1878, “that most of what we have learned respecting the physical constitution of the sun has been gained by the hiding of it from view.”
THE VERY IDEA THAT scientists might discern the physical constitution of the sun and other celestial objects had, until recently, seemed preposterous. “[W]e will never by any means know how to study their chemical composition or mineralogical structure,” the French philosopher Auguste Comte, who pondered the limits of scientific knowledge, declared confidently in 1835, when few would have challenged his assertion. After all, mankind could sense the stars and planets only by the light they gave off. How, then, could one possibly take their measure as material entities?
The answer lay in the light itself. Isaac Newton, in the seventeenth century, had famously demonstrated that a prism will break white light into a rainbow. Much later, scientists put this technique to use in the laboratory. They placed various substances into flames and examined the spectrum of light emitted, and found that each chemical element produced characteristic colors. Sodium’s light, when passed through a prism, showed two different shades of yellow. Lithium exhibited a brilliant red line and a faint orange one. Potassium glowed in red and violet. Scientists could therefore identify the chemical makeup of any hot, glowing gas by looking for this hidden code in the light it gave off. To conduct their studies, researchers fitted telescopes with prisms, producing spectroscopes. “As the geologist with his hammer breaks up the rocks of earth and determines their composition, so with the spectroscope the astronomer breaks up the light proceeding from the heavenly bodies, and shows its nature in the colors of the spectrum,” explained Maria Mitchell.
THE SPECTROSCOPE.
The spectroscope offered a new tool to solve the sun’s riddles, and by the mid–nineteenth century, astronomers were keen to train it on the mysterious apparitions visible only during a total solar eclipse. Scientists therefore launched expeditions to chase the moon’s shadow.
A TOTAL SOLAR ECLIPSE occurs somewhere on earth approximately every eighteen months, but reaching the path of totality is often problematic. Eclipse paths snake across the globe like spaghetti thrown at a map. They traverse oceans more often than land, remote regions more often than populated ones. Some eclipses can be seen only at high latitudes, skirting the North or South Pole.
The scientists who planned expeditions had to examine each eclipse path carefully and consider where to erect observation posts, weighing logistical concerns and climate. An ideal spot must be reachable with a ton or more of scientific equipment, and it should boast good prospects for clear skies, because a single misplaced cloud at the crucial moment could obscure the view and render the entire enterprise worthless. Expeditions required months of planning and weeks of travel, but scientists measured success in mere seconds of observation. In an extreme case, a total solar eclipse may last more than seven minutes, but most last less than three. (The longest eclipses occur when the moon is closest to the earth; at this point in its orbit, the moon appears especially large in the sky and therefore blocks the sun for a greater time.)
In the international race to study solar eclipses, Europeans had taken an early lead. Between 1851 and 1875, scientific parties from England, France, Germany, Italy, and Russia journeyed to Norway, Sweden, Spain, Sicily, India, Ceylon, Siam, the Arabian Peninsula, and Africa (North and South). The
se expeditions yielded key discoveries. During the eclipse of 1860, British astronomer Warren De La Rue took successive photographs of the rose-colored prominences and showed that they were physical features of the sun, not the moon, which covered them by degrees. In 1868, French astronomer Jules Janssen used his spectroscope to reveal the chemical makeup of those prominences: superheated hydrogen gas. Janssen and others also noticed a puzzling yellow line in the spectrum, which British astronomer J. Norman Lockyer, conducting further study after the eclipse, concluded was due to an as-yet-unknown chemical element in the sun. Lockyer named it helium. (It would take scientists another three decades to discover the element on earth.)
The Europeans returned from their travels not just with discoveries, but with epic tales of derring-do. The British physicist John Tyndall, after observing the Mediterranean eclipse of 1870, recalled braving seas so rough “that my body had become a kind of projectile, which had the ship’s side for a target.” Norman Lockyer’s voyage that same year proved even less enjoyable. His party’s steamer, the H.M.S. Psyche, struck rocks off Sicily, and although rescuers saved everyone aboard, clouds on eclipse day obscured all but one and a half seconds of totality. But the bravest exploit was that of Jules Janssen, the intrepid Frenchman. Trapped in Paris by the Prussian siege yet determined to witness the eclipse of 1870 in North Africa, Janssen miraculously escaped by balloon, flying over enemy lines at dawn on his way to Algeria.
Americans, too, had chased eclipses with gusto, but with considerably less success. The nation’s first organized expedition had actually transpired during the tail end of the Revolutionary War. Harvard professor Samuel Williams calculated the path of an eclipse to occur in October 1780, and he found that it crossed the Gulf of Maine in a region held by British forces. John Hancock, the speaker of the Massachusetts House of Representatives and the state’s governor-elect, appealed in a gentlemanly manner to the enemy commander “as a Friend of Science” to let the astronomers through. Under the terms of a truce, the British permitted Professor Williams to erect his observation post on an island in the computed path, but—embarrassingly—at the moment when the sun should have been completely obscured, it was not. Either because of Williams’s own miscalculations or a faulty map that misstated the island’s latitude (Williams blamed the latter), the Harvard expedition had inadvertently placed itself just outside the path of totality.
H.M.S. CALEDONIA AND TWO STEAMERS ATTEMPTING TO TOW H.M.S. PSYCHE OFF A SUNKEN ROCK ON THE COAST OF SICILY.
Eighty years later, a young Simon Newcomb, working at the Nautical Almanac Office, computed the path of an eclipse that would traverse the upper reaches of North America, and he was dispatched to meet the moon’s shadow in the wilds of what today is central Manitoba. It was, even by the era’s crude standards, an uncomfortable slog: forty-seven days’ travel by train, stagecoach, wagon, steamboat, and birch bark canoe, made interminable by squadrons of mosquitoes and a diet of pemmican—dried buffalo meat and rendered fat fashioned into cakes so hardened they required a hatchet for eating. When Newcomb and his companions finally arrived within the belt of totality, they discovered themselves mired in a vast marsh. “The country was practically under water,” Newcomb wrote. “We found the most elevated spot we could, took out our instruments, mounted them on boxes or anything else in the shallow puddles of water, and slept in the canoe. Next morning the weather was hopelessly cloudy. We saw the darkness of the eclipse and nothing more.” With little to show for their odyssey, the men collected insect, fish, and fossil specimens for Harvard’s natural history museum and then reversed the journey, spending the next sixty-three days trudging home.
America’s best opportunity to study the hidden sun had come in 1869. That August, a total eclipse crossed obliquely down the eastern half of the country, from Dakota Territory to North Carolina. Congress appropriated $5,000 to underwrite the expenses of astronomers heading to the path of totality, and many did so, including Simon Newcomb, Maria Mitchell, and the rival planet hunters C. H. F. Peters and James Craig Watson, all of whom observed from Iowa. Despite storms the day before, fair weather prevailed for the eclipse, and the astronomers turned their telescopes, spectroscopes, and cameras upon the corona and solar prominences—one of which, appropriately from Iowa, looked like an ear of corn sprouting from the blackened sun. The Americans published a slew of findings, but most were of little note. (One exception was an unexplained green line seen in the spectrum of the corona that some would attribute to an element, like helium, not known on earth. Later dubbed coronium, the substance would eventually turn out to be an unusual, highly ionized form of iron.) British astronomer Norman Lockyer, helium’s discoverer, wrote generously and perhaps a bit patronizingly, “[T]he American Government and men of science must be congratulated on the noble example they have shown to us, and the food for future thought and work they have accumulated.”
OBSERVING THE ECLIPSE.
Simon Newcomb heard very different comments through back channels. “[O]ne of our scientific men who returned from a visit abroad [declared] that one of our eclipse reports was the laughing-stock of Europe,” he reported.
NOW, IN 1878, another solar eclipse would finally provide a chance for the United States to bolster its scientific reputation. But when European astronomers inquired what the U.S. government planned to do to observe the event, Simon Newcomb could reply only with embarrassment.
“It is doubtful whether we shall have any regularly organized government parties in the field,” he wrote to James Ludovic Lindsay, better known as Lord Lindsay, who had organized a private British eclipse expedition to Spain in 1870. “I would be very glad if it could tempt over some European observers, especially yourself.” Newcomb further explained his frustration to Britain’s Norman Lockyer. “[I]t is still uncertain whether Congress will appropriate any money for the observations,” Newcomb noted, adding, “I fear the question will remain unsettled till it is too late to make efficient preparations.”
As an occasional guest at the Hayes White House and a close acquaintance of the influential Ohio Congressman and soon-to-be President James A. Garfield, Newcomb likely lobbied in the background, hoping quietly to spur the government to action. The U.S. Naval Observatory, meanwhile, lobbied openly.
The Naval Observatory, the U.S. government’s chief sponsor of astronomical research, had grown from humble beginnings. In 1842, Congress had authorized the Navy merely to erect a small facility for keeping time by tracking the stars, but over the years it had expanded in size and purview. By the 1870s, the observatory possessed the largest refracting telescope in the world and housed it in an impressive building, although the location proved unfortunate given that the nearby Potomac mudflats plagued the scientists with fog and malarial mosquitoes.
THE GREAT EQUATORIAL—UNITED STATES NAVAL OBSERVATORY.
As the eclipse of 1878 loomed, the Naval Observatory’s superintendent, Rear Admiral John Rodgers, proposed sending seven government parties to the path of totality, from Montana to Texas. Establishing multiple posts, spaced widely, would increase the odds of at least one party enjoying clear skies. Rodgers made his case for funding to the House Committee on Appropriations in March 1878.
“The sun is the source of all light, heat and life existing on the earth,” Rodgers wrote. “Many questions relating to the physical constitution of that orb can only be studied during a total eclipse, and as the entire sum of all the opportunities which all the astronomers of the world can get to observe such eclipses does not exceed five or six hours in a century, it seems the part of prudence to utilize these precious moments to the utmost, and not allow one of them to pass unheeded.”
Rodgers also appealed to lawmakers’ patriotic pride. “Amongst nations, as with individuals in society, one who occupies a prominent place must, if reproach is to be avoided, bear his part in expenses directed to the general well-being. The United States is at once too enlightened, and too important, a member of the confraternity of nations, to avoid a burden wh
ich falls naturally to her. If other nations send costly expeditions to the antipodes to observe eclipses, the United States can scarcely refuse to observe one within its own borders.”
Rodgers requested money to transport men and equipment to the western frontier. He did not ask Congress to pay salaries; the Naval Observatory would seek astronomers willing to volunteer for duty. The total request: $8,000, a pittance by modern standards, hardly much more in 1878.
The House declined to fund it.
“This seems to be another instance of unjust discrimination against the far West,” railed The Denver Daily Tribune. “If the approaching total eclipse had been appointed for the White Mountains, for Boston, for New Orleans, for the peaks of the Virginia mountains, for Philadelphia, for Chicago, San Francisco, Kansas City, or even perhaps Topeka, Congress would have treated it with proper respect and due consideration, would have recognized its claims, and would have made ample provision for its observation. In fact, Congressmen would no more have allowed it to go unobserved than they do the handsome female lobbyists that visit their hall.”
The New-York Tribune was inclined to agree, similarly rebuking Congress for its inaction. “The lame excuse for this is that the committee were not fully informed as to the importance of the matter; let us hope that, when it is again brought before Congress, there will be no chance for the plea of ignorance on the part of our legislators.”