The Glass Universe

by Dava Sobel

  “The same sky overarches us all,” Pickering avowed when he submitted the list of awardees to the Scientific American Supplement. As usual, he hoped that word of one donor’s generosity would spur others to follow suit. But no one proved more motivated by the outcome than Miss Bruce herself. She felt a particular obligation to astronomers whose plans had arrived too late for consideration.

  “My dear Professor,” she wrote Pickering on February 10, 1891, “I am sorry that so lately as the date of your letter, Jan. 10th, applications still came in, and to see clearly that mixed with some good we have done some harm, for these are disappointed persons, even in some cases mortified—though in fact without cause.” She urged Pickering to assess a new crop of astronomers whose projects she could assist.

  All this time, Miss Bruce’s lavish gift to Harvard still lay in the bank unused, awaiting the arrival of the lens disks from Paris. Pickering’s queries to the glassmaker, Mantois, went unanswered, as did letters and cablegrams sent from the Clarks. After eighteen months, Miss Bruce denounced “that miserable laggard Mantois,” and wished she could confront him in person, confident that her command of French was “probably at least as good as his.”

  In the spring of 1891, nearly two years after Pickering placed the lens order, he discovered to his distress that Mantois had not even begun to form the glass.

  “I shall be only less glad than you when the disc arrives and Clark finds it satisfactory,” Miss Bruce sympathized on April 9. “Let your patience hold out a little longer—another two years or so—and what are two years in the calculations of an astronomer?”

  • • •

  WILLIAM H. PICKERING, the designated first director of Harvard’s southern observatory, reached Arequipa in January 1891. He viewed his arrival as the foundation of a dynasty. His brother already ruled the familiar realm of the northern skies from Cambridge, while here below the equator William would explore the lesser known heavens and establish his own reputation. True, he supervised only two astronomical assistants for the moment, but he presumed the need for a larger staff in Peru would become apparent as soon as the rainy season ended and observations commenced.

  William first had to lease or buy land in the area the Bailey brothers had scouted. Solon and Ruth Bailey were packing to go home, vacating their rented house in Arequipa so the Pickerings could move into it. William had come accompanied by his wife, Anne; their two toddlers, Willie and Esther; Anne’s widowed mother, Eliza Butts of Rhode Island; plus a nurse. To accommodate his family in accord with his sense of mission, he treated the $500 sum he had been allotted for land acquisition as merely the down payment on an expensive property. There he began construction of several permanent buildings for the telescopes, and also a commodious hacienda, complete with servants’ quarters and stable. In February, after only a few weeks in residence, William cabled Edward, “Send four thousand more.”

  By Western Union and stern letters in longhand, Edward tried to make William hew to a stricter economy. In addition, the older brother repeatedly pressed the younger to get busy taking pictures. The Henry Draper Memorial hungered for more photographs of southern stellar spectra. Why did William not make use of the Bache telescope already set up on-site, even as he oversaw the erection of shelters for the three additional telescopes he had brought to Peru? (Over a comparable period during the first expedition in 1889, Bailey had returned some four hundred plates.) In April, William finally obeyed, but still delayed sending the photographs to Cambridge. By August, Edward complained in exasperation, “I am very glad that you have 500 plates but very sorry that they are not here. I am very anxious lest some mistake regarding instructions may make them worthless.”

  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 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 th
em 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 Astrono
my 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.