The Glass Universe: The Hidden History of the Women Who Took the Measure of the Stars

William had never been happier, never enjoyed better seeing—the astronomer’s term for atmospheric conditions. He loved the clear, still mountain air of the Andes that enabled him to resolve unprecedented fine detail on the surfaces of the Moon and planets. Although the solar system was not the focus of any Harvard program planned for Peru, the planets now absorbed William’s attention almost to the exclusion of photometry and spectroscopy. Despite his early devotion to photographic technique, William backslid into visual observing at Arequipa. The 13-inch Boyden telescope, with which he photographed the eclipse in California, had suffered some damage to its clock drive on the journey south, rendering it temporarily unfit for long-exposure photography. Until new parts were in place, William felt free to savor the view through the instrument. It had a reversible lens that rendered it equally fit for the eye or the camera. Even after the needed repairs to the 13-inch were completed, and it stood ready to photograph the spectra of the brightest southern stars, William preferred to peer through its eyepiece and sketch the landscape of Mars.

While William neglected his duty in Peru, Mantois in Paris honored other lens orders ahead of Harvard’s. Miss Bruce deputized J. Cleaves Dodge, an old family friend living in France, to visit the glazier in the hope of rousing him to action on her telescope.

“We are not in luck,” Miss Bruce told Pickering on October 1, 1891, “decidedly not— Accept my condolences. Here is another cause of delay— Before you see all those discs you will have discovered your first grey hair and I! I shall be in cool repose in Greenwood [Cemetery]. But read Mr. Dodge’s letter.”

The enclosure described a cordial, half-hour conversation in which M. Mantois explained to Mr. Dodge “the mysteries of Crown and Flint glass, which to manufacture and to manipulate, as he seems to do, one must be a real alchemist.” This was hardly an exaggeration. Telescope lenses required glass made from the highest-quality materials, mixed according to secret recipes, and heated for weeks at temperatures above one thousand degrees in guarded foundries. The terms “crown” and “flint” distinguished the two basic types of glass by the added quantities of lead in the latter. Used alone, either crown glass or flint glass yielded lenses that brought different wavelengths of light to different focal points, creating a jumble of color distortion known as chromatic aberration. United, however, crown and flint corrected each other. As Joseph von Fraunhofer demonstrated in the early nineteenth century, a “doublet,” formed by a convex lens of crown glass paired with a concave complement of flint glass, could bring the focal points into better alignment.

“The trouble in the making of the lenses,” Dodge’s report to Miss Bruce continued, “seems to be the numerous accidents that occur in the firing and baking of the very best specimens, and which no human intelligence can foretell.” Mantois had lost months to bad luck with a 40-inch lens commissioned by another university and could not yet say for certain when he might satisfy Harvard, willing though he was. Dodge reproduced a verbatim recital of the man’s plight: “M. Mantois said, ‘You see I am as interested as anyone in the completion of the work, for I am not paid anything till it is all finished, but I can only send that which is perfectly satisfactory. Besides I am constantly in a great state of anxiety as to the baking of the molds; I have tubes connected with my bed to warn me at night if the fires are cooling; and the falling asleep of one of the watchmen may cost me no end of trouble and expense.’” Dodge left Mantois’s establishment convinced that no other career in manufacturing “is attended with more chances of failure than this one of glazier for telescopes.”

• • •

HAVING CLASSIFIED TEN THOUSAND STARS, Mina Fleming turned her organizational gift to the arrangement of the ever-multiplying glass plates. The myriad photographs filled many wooden chests shelves and cupboards in both the computing rooms and the library. She imagined they would soon exceed all available space in the observatory building. In the interim she filed them by telescope and by type—the chart plates that mapped each section of the sky, the group spectra, the individual bright spectra, the star trails, and so on—each one in a brown paper envelope, each envelope labeled by number, date, and other identifying details, all of which were repeated on index cards in a card catalogue. Rather than pile the plates in columns, she stood them on edge for easy access. Reason to revisit one or another stored plate arose daily as the assistants examined, measured, discussed, and performed computations upon each new batch of photographs. When, for example, Mrs. Fleming spotted a spectrum that struck her as characteristic of a variable star, she did not need to wait for future observations to confirm her hypothesis. The evidence of the past would bear her out in the now. She had only to consult her records to see which photographs included that portion of the heavens, then pull the relevant plates from the stacks and compare the star’s current state with all its previous manifestations.

“So you have, ready to hand and for your immediate use,” Mrs. Fleming pointed out in a summary of her method, “the material for which a visual observer might have to wait” a very long time, perhaps indefinitely. Moreover, the plates trumped any visual observer’s report, “for in the case of the observer, you have simply his statement of how the object appeared at a given time as seen by him alone, while here you have a photograph in which every star speaks for itself, and which can at any time, now or in the years to come, be compared with any other photographs of the same part of the sky.”

Early in 1891, after she had identified a new variable in the constellation of the Dolphin, and, with the director’s approval, published her finding in the Sidereal Messenger, two skilled observers from other institutions took it upon themselves to corroborate the discovery. Both contested her claim, declaring the star not variable. When those same two astronomers met to discuss their conclusions, however, they realized they had each been watching a different star, neither of which was in fact Mrs. Fleming’s star. “No such error,” she all but crowed, “could have occurred from the comparison of the photographic charts.”

Detecting new variable stars had become Mrs. Fleming’s forte. Although fewer than two hundred such inconstant lights were known when she joined the observatory staff, the decade of her employment flushed out a hundred more, of which she personally identified a score. She made her earliest finds while gauging magnitudes by the size of the speck a star created on a photographic plate, and then noting which specks changed size in subsequent pictures. Spectra gave her an easier means. Once she had familiarized herself with the spectral features of a few well-known variables, she could recognize similar traits in other stars, almost at a glance. For example, the presence of a few light hydrogen lines among the black ones signaled a variable star near the height of its brightness.

As Mrs. Fleming ferreted out new variables, she also kept a close watch on the old. The director was keen to monitor how the spectra of variable stars changed over time, and the ways that variations in brightness correlated with the appearance of the Fraunhofer lines.

In the spring of 1891, Mrs. Fleming noticed something unusual about the familiar variable called Beta Lyrae. Its changeable nature had been known for a hundred years, but now, looking at its magnified spectrum, she recognized the doubled lines signifying that Beta Lyrae belonged to the newly defined group of spectroscopic binaries—that this star was in fact two stars.

Miss Maury also took an interest in Beta Lyrae, even a proprietary interest, given that Lyra (the Harp) was a northern constellation, and she had charge of the approximately seven hundred brightest stars of the northern skies. Together with Pickering and Mrs. Fleming, she reviewed twenty-nine Draper Memorial plates that contained images of Beta Lyrae. Her analysis suggested this binary did not comprise identical twins, as was the case for Mizar and Beta Aurigae, but two stars of different classes, each varying at its own rate and for its own reasons. She began to frame a theory about the nature of their relationship.

Pickering had hoped to publish Miss Maury’s classification of the northern bright stars by the end of 1891, as a sequel to Mrs. Fleming’s 1890 “Draper Catalogue of Stellar Spectra.” Unfortunately, Miss Maury seemed nowhere near ready to release her results. Her two-tiered classification system, which addressed both the identity and the quality of the spectral lines, required a painstaking exactitude. Anything less would deny the complexity of the problem. Although her slow pace disturbed Pickering, he could hardly accuse her of slacking. She had taken on a second job as a teacher in the nearby Gilman School, while still pursuing her observatory work so assiduously that he feared she neglected her health. Mrs. Draper, too, grew impatient with her niece. After a visit to the observatory in early December, she wrote Pickering, “I do hope Antonia Maury will make an effort and finish more satisfactorily what she has in hand.”

Pickering stopped daily by the computing room to monitor the assistants’ progress. Miss Maury shrank from these encounters. She often went home feeling tired and nervous, and more than once complained to her family that the director’s criticism had shaken her faith in her own ability. Incapable of continuing under such conditions, she quit the observatory early in 1892. Through the next few months she negotiated with Pickering about the fate of her unfinished projects, which she refused to abandon or cede to anyone else.

“I have had in mind for some time to explain to you,” she wrote on May 7, “how I feel in regard to the closing up of my work at the Observatory. I am willing and anxious to leave it in satisfactory condition, both for my own credit and in honor of my uncle. I do not think it is fair to myself that I should pass the work into other hands until it is in such shape that it can stand as work done by me. I do not mean that I need necessarily complete all the details of the classification, but that I should make a full statement of all the important results of the investigation. I worked out the theory at the cost of much thought and elaborate comparison and I think that I should have full credit for my theory of the relations of the star spectra, and also for my theories in regard to Beta Lyrae. Would it not be fair that I should, at whatever time the results are published, receive credit for whatever I leave in writing in regard to these matters?”

Pickering stood ever ready to credit her. He just wished he had some idea of when that occasion might arise.

• • •

MISS MAURY’S DEPARTURE at the start of 1892 coincided with the long-awaited arrival from France of the Bruce telescope’s glass disks, two of flint and two of crown, each two feet in diameter by three inches thick, weighing in the neighborhood of ninety pounds, and rimmed in a metal hoop. The flawless purity of the glass rendered the disks invisible, and therein lay their beauty. Pickering immediately consigned them to the Clarks for the all-important grinding and polishing. He expected the transformation of the disks into the four-element portrait lens to take at least six months of long days on the Clarks’ steam-powered lathe. First the glasses would be abraded with rough sand, then by ever-finer rouge powders, until they assumed the desired curvature.

While that process was under way, Pickering drew plans for a freestanding structure in which to assemble and try out the finished instrument. The Bruce telescope must pass his own stringent tests before he could ship it to Arequipa. And Arequipa, in turn, must be readied to receive it. On May 29 he notified William, who had disappointed him, that his term as southern director would expire at the end of the year, at which time Solon Bailey would replace him. William could return in future to observe at the site, if he liked, but he would no longer be in charge.

William recoiled at the insult. “Without being boastful, I think I’ve accomplished a pretty big thing,” he argued on June 27, 1892, “and if the authorities [the president and fellows of the Harvard Corporation] could see it they would say I had got them a great deal for their money.” The idea of subservience to Bailey particularly rankled William: “As to our coming down here again to Peru and living in a small hut, while the Baileys occupy the Director’s house, it is out of the question. I planned and built that house, and while I am in Peru I expect to live in it. I don’t choose to live in a shanty while one of my subordinates occupies the house I built.”

All through the summer of 1892, William soothed himself by studying Mars during its close approach. As he reported in Astronomy and Astro-Physics, he observed and drew the red planet every night save one from July 9 to September 24. He collected “considerable data” on the Martian polar caps, the shaded areas “of greenish tint,” and the two large, dark regions that, under favorable conditions, turned blue “presumably due to water.” He referred to these as “seas.” He corroborated the numerous Martian “canals” originally discovered by Giovanni Schiaparelli of Italy, and noted that many of them intersected one another—at junctions he dubbed “lakes.” William communicated these same findings to the editors of the New York Herald, who printed them to sensational effect. An exasperated Edward Pickering complained to William on August 24 that the waters of Mars had generated a “flood” of forty-nine newspaper cuttings in one morning. He admonished William to restrict himself “more distinctly to the facts.”

Meanwhile Edward and Lizzie Pickering were looking to remodel the “dwelling house” in the observatory’s east wing. Although they had no children, nor any personal need for extra space, they expanded the observatory apartments, at their own expense, to accommodate and entertain visiting astronomers. Pickering was content to have the college continue docking his $4,000 annual salary for amounts considered rent, but he asked that henceforth the monthly sums be allocated solely for the observatory’s use, instead of for Harvard at large, as had been customary. Despite frequent gifts from active donors and the receipt of important new bequests, the director feared it might take years for the budget to recover from William’s profligacy in Peru.

Miss Bruce, unaware of William’s indiscretions, followed his publications in the astronomy literature. “The two articles in the May number of AstroPhysics from the pen of your brother,” she wrote Pickering in August, “have given me great pleasure and caused me to reflect on the happiness that you must have in working thus into each other’s hands.” She imagined Edward and William to be as close to each other as she was with her sister Matilda, ten years younger, who lived with her and helped her in a hundred ways.

The following month gave both Pickering and Miss Bruce genuine cause for shared happiness. “I hold out my hand to grasp yours,” she effused on September 9, when she heard that the lenses for the large photographic telescope had passed their first examination. “Let us rejoice.”

In October, as though in atonement, William resumed photography at Arequipa for the Henry Draper Memorial. By the end of December 1892 he had shipped two thousand plates to Cambridge.

• • •

ALMOST FROM THE MOMENT stars began amassing on Harvard’s glass photographic plates, the director developed a dread of their destruction by fire. The larger the collection grew, the more devastating the contemplation of its loss, should the wooden observatory building ignite. Virtually everyone of Pickering’s acquaintance had lost something of value to a conflagration. Mrs. Draper’s family, for one, owned a theater in Union Square that burned to the ground in 1888, and its reconstruction continued to cause her grief. Consequently she had become something of an expert on fireproof paint, periodically urging its application to the observatory.

Pickering favored an alternate solution. In 1893 he announced the completion of a two-story “fire-proof building,” made entirely of brick, for the safe storage of glass plates and manuscripts of yet-to-be published results. The Brick Building, as everyone soon came to call it, crowned Pickering’s fifteen years of site improvements, from the numerous telescope domes and sheds to the neighboring house on Madison Street that had been transformed into a photography workshop and darkroom. In the words of journalist Daniel Baker, whom Miss Bruce commissioned to write up the observatory’s history, the hilltop once dominated by a single edifice had become a “little city of science.”

Mrs. Fleming oversaw the packing of the thirty thousand plates into three hundred crates. On March 2, 1893, workers rigged a block and tackle from the roof of the observatory’s west wing to a window of the new repository. Then they slid the approximately eight tons of plates down the rope skyway at the rapid clip of a crate per minute. Despite the precarious flight, not one piece of glass cracked or shattered.

Naturally Mrs. Fleming and most of the computers followed the plates into the new space, to remain close to them. They traveled at ground level by a wooden walkway over the muddy intervening ditch. When Miss Maury returned to join them in the spring, Pickering asked for her promise to complete her classification before the end of the year or turn over the work to someone else, and she signed a statement saying that she would.

There were now seventeen women computing at the observatory. In other words, nearly half of the observatory’s forty assistants were female—a fact Mrs. Fleming intended to emphasize in her invited remarks for the upcoming Congress of Astronomy and Astro-Physics in Chicago.

The name of the congress called attention to astronomy’s increasing emphasis on the physical nature of the stars through spectroscopy. Some self-styled astro-physicists were already distancing themselves from the more traditional observers who concentrated on stellar positions or cometary orbits. George Ellery Hale trumpeted the new trend. He had been briefly associated with Harvard while a student at MIT, before establishing his own Kenwood Observatory in his native Chicago in 1890. It was Hale who prevailed upon the editor of the Sidereal Messenger to change the publication’s name to Astronomy and Astro-Physics in 1892. And it was again Hale who organized the August 1893 Congress of Astronomy and Astro-Physics. By timing the meeting to coincide with the Chicago World’s Fair, or Columbian Exposition, he added incentive for astronomers from either coast and other continents to undertake the journey.

Hale invited Pickering to present the opening address to fellow scientists at the conference, as well as a broader, less technical talk to inform the fair-going public about the fabric of the stars. Hale also requested an exhibit’s worth of photographs documenting the work of the Harvard College Observatory and its physical plants in Cambridge and Arequipa. Pickering included photographs of the women at work in the new Brick Building.

Pickering began preparing the text for his popular address well in advance. “Our only knowledge of the constitution of the stars,” it began, “is derived from a study of their spectra.”

Mrs. Fleming also prepared an invited paper for the Astronomy and Astro-Physics congress. The previous summer in Chicago had seen the two women’s rights federations merged into one “National American Woman Suffrage Association.” This year, soon after the Exposition opened in May 1893, suffragettes Julia Ward Howe and Susan B. Anthony had made impassioned presentations. Though Mrs. Fleming fully affirmed the principle of equality, she was not an American citizen, and the feminist struggle for the right to vote was not her fight. The cause she championed was equality for women in astronomy: “While we cannot maintain that in everything woman is man’s equal,” Mrs. Fleming averred in her Chicago contribution, “yet in many things her patience, perseverance and method make her his superior. Therefore, let us hope that in astronomy, which now affords a large field for woman’s work and skill, she may, as has been the case in several other sciences, at least prove herself his equal.”

The White City of the Columbian Exposition, with its two hundred grand structures, held numerous fascinations for Anna Draper, who visited the fair in mid-June. The Woman’s Building had been designed by Sophia Hayden, the first of her sex to receive a degree in architecture from MIT, and its interior bore murals and paintings executed by well-known female artists such as Mary Cassatt. Other not-to-be-missed highlights included the Electricity Building’s seventy-foot-tall tower of lightbulbs and the Hall of Agriculture’s fifteen-hundred-pound copy—in chocolate—of the Venus de Milo. Inside the Manufacturers’ Building, Mrs. Draper stared up at the mammoth mounting pier and tube of a new telescope that would soon move to a permanent home on the shores of Lake Geneva in Wisconsin. The tube stood empty. Its 40-inch object glass—the very monster that had vied with the Bruce lens for priority in Mantois’s Paris establishment—still lay hundreds of miles back East, on the lathe at Alvan Clark & Sons.

By late summer, progress on the Bruce telescope had reached a critical stage. Only William Pickering was free to represent the Harvard Observatory at the astronomy conference in Chicago. When Mrs. Fleming’s speech was read aloud for her at the session held Friday, August 25, William seconded her statements in praise of the efficient women’s force in Cambridge. The next day he presented his own report, titled “Is the Moon a Dead Planet?,” in which he answered his own question with an emphatic “No.”

In early September the first piece of giant iron superstructure for the Bruce telescope made its slow way up Summerhouse Hill. Placement of the two-ton bed plate occupied six men and four horses for a full day. Edward Pickering watched the “ponderous affair” of assembly wear on for two more months before he got the proof he needed to declare the whole grand giant-telescope enterprise entirely worthwhile.

“We have obtained some remarkable photographs,” he wrote Miss Bruce on November 19. “I can now safely report its assured success, and can congratulate you on having the finest photographic telescope in the world.”

CHAPTER FOUR

Stella Nova

NOTHING IN THE SKY SURPRISED an astronomer more than the sudden apparition of a new star where none had been seen before. When the legendary Tycho Brahe of Denmark glanced skyward one night and beheld such a sight, he declared it “the greatest wonder that has ever shown itself in the whole of nature since the beginning of the world.” De nova stella, Tycho’s eyewitness account of the 1572 marvel, argued that Aristotle had been wrong to call the heavens immutable. Surely the abrupt appearance of the new star and its subsequent disappearance a year later proved that change could occur in the realm beyond the Moon.

Not long after Tycho died in 1601, another nova burst into splendor. Both Galileo in Padua and Johannes Kepler in Prague observed the brilliant new star of 1604, which was so bright as to be visible in the daytime for more than three weeks. Although no comparable naked-eye nova ever materialized over the following centuries, a few fortunate astronomers who happened to be pointing their telescopes to the right place at the right time discovered seven more novae between 1670 and 1892. Then Mina Fleming found one. On October 26, 1893, while hunched over her light lectern with a magnifying glass during a routine perusal of a photographic plate newly arrived from Peru, she seized on a star with the peculiar spectrum unique to a nova—a dozen prominent hydrogen lines, all of them bright.

The director cabled the exciting news to Solon Bailey, who had taken the photograph more than three months earlier, on July 10. Pickering hoped new pictures by Bailey would disclose what, if anything, remained of the nova. Meanwhile Mrs. Fleming looked back in time through the plates to see what had preceded it, but found no trace in prior photographs of the same region. The star must have been dim indeed before its leap from obscurity to seventh magnitude.