The Glass Universe

by Dava Sobel

  Pickering challenged Mrs. Fleming to improve on this elementary class system. Whereas Secchi had sketched his spectra from direct observations of a few hundred stars, she would enjoy the advantage of the Henry Draper Memorial photographs, boasting thousands of spectra for her scrutiny. The glass plates preserved more faithful portrayals of the positions of Fraunhofer’s lines than drawings could ever provide. Also, the plates picked up lines at the far violet end of the spectrum, at wavelengths the eye could not see.

  • • •

  MRS. FLEMING REMOVED EACH GLASS PLATE from its kraft paper sleeve without getting a single fingerprint on either of the eight-by-ten-inch surfaces. The trick was to hold the fragile packet by its side edges between her palms, set the bottom—open—end of the envelope on the lip of the specially designed stand, and then ease the paper up and off without letting go of the plate, as though undressing a baby. Making sure the emulsion side faced her, she released her grip and let the glass settle into place. The wooden stand held the plate in a picture frame, tilted at a forty-five-degree angle. A mirror affixed to the flat base caught daylight from the computing room’s big windows and directed illumination up through the glass. Mrs. Fleming leaned in with her loupe for a privileged view of the stellar universe. She had often heard the director say, “A magnifying glass will show more in the photograph than a powerful telescope will show in the sky.”

  Hundreds of spectra hung suspended on the plate. All were small—little more than one centimeter for the brighter stars, only half a centimeter for the fainter ones. Each had to be tagged with a new Henry Draper catalogue number, and also identified by its coordinates, which Mrs. Fleming determined using the millimeter and centimeter rules inscribed on the wooden plate frame. She read off these numbers to a colleague who sat beside her, penciling the information into a logbook. Later they would match the Henry Draper numbers to the stars’ existing names or numbers, if any, handed down from previous catalogues.

  In the rune-like lines of the spectra, Mrs. Fleming read enough variety to quadruple the number of star categories recognized by Father Secchi. She replaced his Roman numerals, which quickly grew cumbersome, with Fraunhofer-style alphabetical order. The majority of stars fell into her A category because they displayed only the broad, dark lines due to hydrogen. The B spectra sported a few other dark lines in addition to those of hydrogen, and by her G category the presence of many more lines had become the norm. Type O bore only bright lines, and Q served her as a catchall category for peculiar spectra she could not otherwise pigeonhole.

  Pickering applauded Mrs. Fleming’s efforts, even as he conceded the arbitrary, empirical nature of her classification. He predicted that in time, with ever more stars studied, the underlying reasons for the different spectral appearances would reveal themselves. Possibly different stellar temperatures were responsible, or different chemical blends, different stages of stellar development, or some combination of such factors—or something as yet unimagined.

  In January 1887 Pickering hit on a way to enlarge some of the spectra from smudge-like traces to an impressive four inches by twenty-four. He astonished Mrs. Draper by sending her several examples. “It scarcely seems possible that stellar spectra can be taken which will bear the enlarging of those that you have sent me,” she wrote on January 23. “I wonder what Mr. Huggins will say when he sees them.” This question stimulated her to strengthen her support of the Henry Draper Memorial, which currently amounted to about $200 a month, by promising $8,000 or $9,000 per year in perpetuity.

  There seemed no reason for Mrs. Draper to cling any longer to the dream of continuing her husband’s research herself. She thought it best to divest the Hastings observatory of his remaining telescopes, and donate the lot to Harvard. The largest, with its 28-inch-diameter mirror, would likely prove a significant aid in Pickering’s pursuits. Still she wavered. It had been one thing to part with the 11-inch-aperture refractor, now ensconced at Cambridge, but the 28-inch reflector preserved precious memories of her wedding day.

  Henry had always preferred reflecting telescopes, which gathered light by means of a mirror in lieu of a lens, over refracting ones that could introduce spurious color effects. He had begun crafting his own mirrors right after medical school, and must have made a hundred in all, but the 28-inch was his great reflector. On November 12, 1867, the day after he and Anna exchanged marriage vows in her father’s living room, they went downtown together to shop for a glass disk—the kind used in skylights—large enough to form a mirror 28 inches across. They referred ever after to that excursion as “our wedding trip.” It took them years to grind and polish the disk to the desired curvature and apply the ultrathin coat of silver that transformed the glass into a perfect mirror.

  The 28-inch reflector had enabled them to take their landmark first picture of the spectrum of Vega in 1872, as well as their unrivaled photograph of the so-called Great Nebula in Orion ten years later, and also their final series of stellar spectra images during the summer before Henry’s death. On one of those humid July nights, undone by overcast skies, the two of them had quit the observatory around midnight to retire. But as they neared their country house two miles away on Wickers Creek in Dobbs Ferry, they saw the clouds dissipating, so they turned the horses around and drove back to Hastings to resume their work. She remembered returning that way on numerous other occasions just to seize a few more hours—even long ago, when they thought they had all the time in the world.

  • • •

  “MRS. DRAPER HAS DECIDED to send to Cambridge a 28-inch reflector and its mounting,” Pickering announced on March 1, 1887, in the first annual report of the Henry Draper Memorial. He praised the project’s benefactress for providing not only the instruments required for the project but also the means for keeping them actively employed by operators “during the whole of every clear night,” and for “reducing the results by a considerable force of computers,” and for publishing them as well. He hoped that other donors would follow her example by similarly endowing astronomy departments elsewhere with the means to function to their fullest.

  In the spring of 1887, while Mrs. Draper negotiated with the Hudson River Railroad for a car to carry the 28-inch to Harvard, the observatory received another huge bounty—approximately $20,000, to be augmented by $11,000 annually—for the establishment of an auxiliary station on a mountaintop.

  Pickering had been climbing mountains all his life. He began summiting in New England with youthful companions who called him “Pick” and even “Picky.” He later measured the heights of points of interest in New Hampshire’s White Mountains on solo treks with fifteen pounds of apparatus strapped to his back. In 1876, around the time he left the MIT physics department to direct Harvard’s observatory, he founded the Appalachian Mountain Club for fellow outdoorsmen, and served as its first president. Still an active member in 1887, he could well imagine the advantage of stationing a telescope at high altitude.

  The source of the sudden windfall was the contested will of Uriah Boyden, an eccentric inventor and engineer who had received an honorary Harvard degree in 1853. When Boyden died in 1879, unmarried and childless, he allotted $230,000 to perch an observatory far above the atmospheric disturbances that plagued astronomers at sea level. Many noble institutions, including the National Academy of Sciences, vied for control of the Boyden estate, but Pickering convinced Boyden’s trustees that Harvard University was the most likely of the suitors to invest the money wisely, and the Harvard Observatory most fit to carry out the testator’s instructions. Triumphant after five years of polite wrangling, Pickering organized an exploratory expedition to the Colorado Rocky Mountains.

  The Boyden Fund gave Pickering the means to hire his younger brother away from MIT. William, likewise a charter member of the Appalachian Mountain Club, thus became the director’s assistant and guide for the western reconnaissance. The brothers left Cambridge in June 1887 along with Lizzie Pickering, three junior volunteers
from the observatory, and fourteen crates of equipment. Mrs. Draper joined them at Colorado Springs in July.

  Although no high-altitude astronomical observatory yet existed in the United States, the federal reservation at Pikes Peak was home to the world’s highest meteorology station, maintained at 14,000 feet by the U.S. Army Signal Corps. This made Pikes Peak the only American mountain where particulars of weather (beyond the statistic of annual rainfall) were known. When Pickering’s party of five men ascended in August, leading mules laden with scientific instruments, they encountered a snow squall, a hailstorm, and a thunderstorm they described as violent. Over the course of the month, they camped and compared conditions on three peaks in the region by various means, such as a sunshine recorder William had modified as a complement to a rain gauge, and also by photographing the sky through a 12-inch telescope. Conditions did not seem optimal. What was worse, rumor had it that Pikes Peak might be turned into a state tourist attraction, and be overrun with non-astronomers.

  Pickering returned to Cambridge without having settled the placement of the Boyden Station. He thought he might revisit the Rockies the following summer, or try a different mountain range.

  In October, after Mrs. Draper returned East, closed her Dobbs Ferry house for the season, and reestablished herself on Madison Avenue, she thanked Pickering for the summer’s adventure with the gift of an ornamental pocket telescope that had once belonged to King Ludwig of Bavaria.

  • • •

  WITH TWO AND OFTEN THREE TELESCOPES taking pictures through the night, the observatory devoured plates at a rapid rate. Between 1886 and 1887, advances in the quality of manufactured dry plates extended their recording range to fainter stellar magnitudes, and Pickering took full advantage of each new development. He tried different companies’ wares and shifted suppliers accordingly; he encouraged manufacturers to keep improving the sensitivity of their plates—and to send him their latest products for testing.

  The volume of data to be calculated rose in proportion to the number of photographs taken. Anna Winlock’s younger sister, Louisa, assumed her place in the computing room in 1886, and was joined the following year by Misses Annie Masters, Jennie Rugg, Nellie Storin, and Louisa Wells. The staff of female computers now numbered fourteen, including Mrs. Fleming, who served as their supervisor. Most of the ladies were younger than she, more or less her social equals, and respectful of her authority. That situation shifted in 1888 with the addition of twenty-two-year-old Antonia Maury, who was not only a Vassar College graduate with honors in physics, astronomy, and philosophy, but also the niece of Henry Draper.

  “The girl has unusual ability in a scientific direction,” Mrs. Draper told Pickering on March 11, 1888, “and is anxious to teach chemistry or physics—and is studying with that object in view.”

  As a child, Antonia Maury was allowed into her Uncle Henry’s chemistry laboratory at the big house in New York City, where she “assisted” him by handing him specific test tubes he requested for his experiments. Before she turned ten, her father, the Reverend Doctor Mytton Maury, an itinerant Episcopal minister, taught her to read Virgil in the original Latin. Her mother, Henry Draper’s sister Virginia, was a naturalist enamored of every bird, flower, shrub, and tree on the Hastings property; she had died in 1885 while Antonia was studying at Vassar.

  Pickering felt uncomfortable offering the standard computer pay of twenty-five cents per hour to a person of Miss Maury’s achievements. He expressed something like relief when she failed to answer his letter, but Mrs. Draper interceded for her through April and May.

  “The girl has been very busy,” the aunt explained. Although Reverend Maury had relocated to Waltham, Massachusetts, for his work, he had neither found a home for his family nor enrolled his two younger children, Draper and Carlotta, in school, leaving Antonia to take charge of these matters. By mid-June she had joined the Harvard corps.

  Pickering assigned Miss Maury the spectral measurement of the brightest stars. Mrs. Fleming had worked from plates containing hundreds of spectra crowded together, and on which the bright stars appeared overexposed. The 11-inch Draper telescope focused on just one star at a time. Each spectrum imaged in this manner spread over an expanse of at least four inches, even before enlarging. The gratifying increase in detail gave Miss Maury much to ponder as she examined the plates under a microscope. In the same blue-violet region of Vega’s spectrum where her uncle had photographed four lines in 1879—and ten in 1882—she now counted more than one hundred.

  Along with measuring the distances between the lines and converting them to wavelengths, she was expected to classify each spectrum according to Mrs. Fleming’s criteria. But Miss Maury had so much more detail to work with that she could not confine her impressions to those parameters. Some of the lines she looked at were not simply thick or intense, but also hazy or fluted or otherwise noteworthy. Such nuances surely deserved attention, for they might illustrate as yet unsuspected conditions in the stars.

  • • •

  WHEN HARVARD’S SECOND MOUNTAIN reconnaissance headed West in November 1888, Pickering opted out. He could not possibly afford enough time away from the observatory to fulfill the mission’s ambitious itinerary, which was to begin site testing near Pasadena, California, and continue among the Andes in Chile and Peru. He put his brother, William, in charge. While in California, the team would also visit the Sacramento Valley to observe and photograph the total solar eclipse of January 1, 1889.

  Ordinarily, Pickering did not support eclipse expeditions, on practical grounds. He deemed the expense too high, given the high risk of failure. An ill-placed cloud during the scant moments of totality could scotch the whole enterprise (as he had learned firsthand when he went to Spain with former director Winlock for the eclipse of December 22, 1870). But if, as in the present case, the path of totality nearly crossed the path of exploration for the new Boyden Station, Pickering would not object to a small detour.

  Favorable weather smiled on the observers for the New Year’s Day eclipse. Excitement at the rare sight, however, shook the astronomers and the large crowd of onlookers alike. At the start of totality, the spectators started to yell. The noise drowned out William’s call to the person counting out the seconds, and his struggle to make himself heard caused him to take fewer pictures than he intended. He also forgot to remove the lens cap from the spectroscope.

  From his disappointment in Sacramento, William went south to Mount Wilson, where he and a few assistants were to test atmospheric conditions by observing for several months with a 13-inch telescope they brought along for that purpose. At the same time, the other half of the team departed for South America. In Pickering’s grand scheme, two mountain observatories were better than one. A California aerie would improve on the work done at Cambridge, while an additional satellite station in the Southern Hemisphere would widen Harvard’s field of view to encompass the entire sky.

  Pickering entrusted control of the South America venture to Solon I. Bailey, age thirty-four, who had joined the observatory staff as an unpaid assistant two years earlier and quickly proven himself deserving of a salary. Like Pickering, Bailey had a younger brother with a talent for photography, and so, with Pickering’s blessing, Solon appointed Marshall Bailey as his second-in-command, and planned to meet him in Panama after the eclipse. Facing a trip expected to last two full years, Solon took along his wife, Ruth, and their three-year-old son, Irving.

  The February 1889 voyage aboard the San Jose of the Pacific Mail gave Bailey occasion to practice his Spanish with several fellow passengers, whose names he recorded in his journal. On deck, he enjoyed watching Venus sink into the sea after sunset, “plainly seen till she touched the water.” In the predawn February sky, he sighted the Southern Cross for the first time. Bailey had loved the stars since his boyhood in New Hampshire, where he witnessed the great natural fireworks of the 1866 Leonid meteor shower. Now he would meet a sky’s worth of new conste
llations, which prospect inured him to whatever hardships lay ahead.

  The bulk of the Andes expedition supplies—everything from photographic plates to prefabricated buildings—traveled with Marshall from New York to the Isthmus of Panama, then overland, past the recently aborted French canal effort and the graveyards of fever victims to another ship bound for Callao, near Lima.

  The party rode the Oroya Railroad twenty miles east from Lima to Chosica, and from there the Bailey brothers ascended on foot and by mule to elevations of 10,000 feet or more. Their native guides nursed them through bouts of altitude sickness with an effective local remedy, namely the odor of bruised garlic. No particular peak impressed Bailey as ideal, but he needed to seize the good weather of the dry season, and so settled for a nameless mountain with the least obstructed view. It stood just over 6,500 feet high, barely accessible by a path that switchbacked up and around for eight miles. The Baileys labored alongside a dozen locals for three weeks to improve the route from the hotel in Chosica to the site, and then helped drag eighty loads of equipment up that road to the makeshift observatory. When the family moved in on May 8 along with their Peruvian assistant, two servants, cats, dogs, goats, and poultry, their only neighbors were centipedes, fleas, scorpions, and the occasional condor. They relied on a muleteer for daily supplies of water and food.

  The Baileys assessed the brightness of the southern stars with the same meridian photometer that Pickering had used in Cambridge, in order to make their observations exactly comparable to his. Similarly, they photographed the southern stellar spectra for the Henry Draper Memorial with the selfsame 8-inch-aperture Bache telescope that had seen nightly duty through the project’s first two years. Mrs. Draper replaced the original workhorse at Harvard with another of the same specifications.

  Solon Bailey stayed in touch with Pickering as regularly as the mails allowed. When he shipped the first two cases of glass plates to Cambridge, he said they came from an as yet unnamed place that he would like to call Mount Pickering.