Starlight Detectives

by Alan Hirshfeld

  On November 15, Henry and Anna Draper hosted a fifty-guest reception for the National Academy of Sciences at their home. As a novelty, Henry had installed in the dining room a set of Edison incandescent lights—several immersed in decorative, water-filled bowls—powered by the gas-driven dynamo in his laboratory. After the dinner, he grew feverish and short of breath, and was carried to his bed. Diagnosed with pericarditis, he died at four in the morning on November 20, 1882, at age forty-five. As his colleague Charles A. Young wrote in The Critic shortly afterward, “It is hard to avoid the appearance of exaggeration in writing of one like Dr. Henry Draper.”

  Chapter 10

  LEAVES OF GLASS

  The camera is an encroaching instrument. So surely as it gains a foothold in any field of research, so surely it advances to occupy the whole, either as adjunct or principal.

  —Agnes Clerke, “Sidereal Photography,” 1888

  THE PUSH INTO DEEP-SPACE PHOTOGRAPHY, exemplified by Henry Draper’s final exposure of the Orion Nebula, accelerated through the 1880s. The dry plate’s sensitivity emboldened amateur astronomers, who sought to surpass the eye’s limited capacity to register the ghostly wisps of the night. With Draper’s death, the locus of innovation shifted from the United States to England, where successors of Warren De La Rue bypassed the snapshot simplicity of lunar photography for the greater challenge of nebular imaging. Even with the recent chemical advancements, an hour’s exposure barely fleshed out the Orion Nebula, much less its dimmer counterparts. Significant engineering hurdles remained. Large-aperture astronomical mirrors could now be ordered from a catalog (at substantial cost), but prefabricated telescope mounts were rife with deficiencies. Celestial photographers required a telescope with a vibration-free pedestal, superb balance, silky-smooth bearings, and a dead-on clock drive—all of it exposed to the adverse conditions of the open-air observatory. It was here that the engineering prowess of English amateur astronomers came to the fore.

  Andrew Ainslie Common was drawn to astronomy in 1851 at age ten, inspired by the technological daring of Lord Rosse and his Leviathan reflector. Common’s elder brother John remarked that, as a youth in the Northumberland town of Morpeth, Andrew “was always at the telescope,” a small refractor their mother had borrowed from a local doctor. The flirtation with astronomy was brief: Andrew’s father, a surgeon, died in 1852 and the once star-struck Andrew turned his attention to his education and his future in a trade. For several years, Common labored at a mill in Gayton, then moved to London in 1864 to join his uncle, Matthew Hall, as a sanitation engineer. Common proved to be a skilled designer and manager. By the mid-1870s, he was running the company’s day-to-day operations and became its chief executive upon his uncle’s death. (The firm evolved into the global design-construction giant SPIE Matthew Hall.)

  Andrew Ainslie Common.

  Although far from a blowhard, Common was an imposing figure, with a broad, bearded face, a wrestler’s build, and a hunger for challenges. A friend described him as “full of enterprise . . . ready to tackle anything”: he once tried to hold up a bicycle at arm’s length, only to wind up in a sling. The same predilection to test one’s limits inevitably found itself applied to a long-deferred interest. Common returned to astronomy in 1874 with the purchase of a five-and-a-half-inch refractor telescope. Marginal attempts at celestial photography convinced him that he needed a bigger instrument. Much bigger.

  In 1877, after an abortive attempt to grind his own seventeen-inch mirror, Common bought an eighteen-inch silvered-glass reflector from George Calver, an East Anglian cobbler-turned-optician, whose instruments had garnered acclaim among English amateur astronomers. Like his American contemporary, Henry Draper, Calver issued a guidebook on the making of an astronomical mirror. Draper had hoped to inspire neophytes to construct their own instruments; Calver was more business-minded: having inundated readers with the complexities of the process, he included a catalog of his own telescopes—with prices.

  Common built a tube for the eighteen-inch mirror and mounted it in a brick-and-glass garden shed in his backyard at Ealing. (The site was ill-suited to astronomy; one contemporary writer described it as “half submerged by the fogs of London.”) Neighbors might have wondered at the mortar-like muzzle that jutted heavenward each night after the shed’s sloped roof was rolled aside. But they would have habituated to the sight of a portly figure atop a ladder, peering intently into the side of the broad cylinder. Had they wandered over, they would have encountered a genial guide to nature, a man to whom “the world was naturally a delightful place.” In the autumn of 1877, Common tracked the moons of Mars and Saturn by eye, then gradually turned to planetary photography. The results, although better than before, underscored the root problem: even an eighteen-inch aperture was too small for Common.

  This time, George Calver embarked on a thirty-seven-inch reflector, four-and-a-half inches thick and weighing more than four-hundred pounds. Four grinding machines scraped away before one was found that could handle the load and not fragment the glass. The raw disk was secured to a tilt-table, laid flat for grinding and polishing, tipped vertically for optical testing. “The work of correcting was tedious and trying,” Calver told the Royal Astronomical Society, “especially in the latter stages, when for every few minutes’ polishing, the whole preparations for testing had to be repeated, and the settling of the mass into its normal state had to be patiently waited for, and often days passed before further advance could be made.” Calver seems to have been blessed with the patience of Job; yet he did confess that his flagging spirits were buoyed by a sit-down with Henry Draper, who commiserated with his fellow mirror-maker. (It was during this 1879 visit to England that Draper learned of the dry-plate photographic process.) Having completed his so-called three-foot reflector, Calver correctly divined the progression of astronomical telescopes: “I see no obstacles to the construction of glass mirrors of very large sizes.”

  Andrew Common prepared for the arrival of his outsize mirror by building a house-like enclosure that rolled aside on iron rails. He mounted the telescope as an equatorial—like a swiveling cannon support, but heeled over so its azimuthal motion paralleled Earth’s rotation. To ensure ease of movement, the ponderous equatorial axle “floated” in a concentric casing filled with mercury. From this base structure rose an eighteen-foot-long steel-strut tube, whose upper end held the accessory optics, including a plate holder. No fan of heights, Common built a broad, enclosed scaffold that raised him safely to the telescope’s eyepiece.

  A daytime snapshot, presumably taken from an upper story of the Ealing house, shows Andrew Common in the middle distance, back to the camera, a mere appendage to the giant optical machine into which he is gazing. The backyard vista captures the Victorian era’s energetic amalgam of the agrarian and the industrial. We see grass, shrubs, stone pathways, gardening tools casually laid aside for their next use; over the fence, a pastoral backdrop of tilled fields and rolling hillocks. And, peering out of their respective shelters like a pair of mechanical beasts, there were the instruments of scientific exploration—one man’s idea of a proper English garden.

  View of Andrew Common’s eighteen-inch and thirty-six-inch telescopes, as seen from his house in Ealing, near London.

  The three-foot reflector was completed in late 1879. Like his Hudson Valley colleague Henry Draper, Andrew Common was drawn almost immediately to the Orion Nebula. The distant cloud represented the photographic frontier, both in terms of literal reach into space and the state of earthbound technology. Common tried to photograph the nebula on the night of January 20, 1880, nine months before Henry Draper’s initial success. The result was dismaying: “The stars were seen as lines,” astronomer Edmund Stone told the Royal Astronomical Society, “and the nebula proper presented merely a faint stain upon the plate.”

  The three-foot telescope was nearly undone by Common’s self-designed mechanics. By placing the entire instrument above and forward of its base, he had created a giant, tottery lever
requiring a massive back-end counterpoise. (Typically, a telescope’s mirror sits aft of the base, helping balance the long tube.) Every time the plate holder was attached or removed, lead slabs had to be added to or withdrawn from a pair of counterpoise boxes. Common’s innovative mercury flotation system was a “delusion,” according to astronomer James Keeler, who used the telescope after it was donated to Lick Observatory in California. The fluid did little to buoy the dead weight of the mount, which bore down relentlessly on a lone steel pivot. The telescope’s clock drive was deficient as well, unable to move the heavy instrument in synchrony with the stars. Tracking of celestial objects was handled by a 1,440-tooth gunmetal gear, forty inches in diameter, which was turned by the slow descent of a weight down an eight-foot shaft. A good photographic telescope in the 1880s could track a star accurately for at least two minutes; Common’s gear-driven behemoth barely managed two seconds.

  Common’s engineering intuition told him that no machine would ever drive the full mass of his telescope with the requisite precision to capture Orion. Instead, he designed a mechanism akin to one used by Henry Draper, which shifted the camera plate itself at the proper rate. To the plate holder, Common affixed a high-power optical sight, allowing him to apply a corrective nudge whenever a chosen guide star strayed from the crosshairs. The faulty clock drive lumbered away, keeping the telescope roughly on target, while Common manually did the rest. After two years of development and testing, Andrew Common was ready to try again.

  On March 18, 1882, four days after Henry Draper took his third and final photograph of the Orion Nebula, Common succeeded in imaging the object himself. But it was his follow-up exposures of thirty-seven minutes on January 30, 1883, and one hour on February 28, that captured Orion’s ethereal splendor far more vividly than any previous rendering by hand or by camera. The direct telescopic view, aquiver from mechanical vibrations and atmospheric disturbances, was here stilled. In this photograph, the observer could linger on the whole or on the details, absent the chill winds, errant clouds, or dew-flecked lenses of the observatory. William Abney, president of the Royal Astronomical Society, called Common’s picture “epoch-making.”

  Andrew Common’s dry-plate photograph of the Orion Nebula, taken in 1883.

  Nor could one fail to appreciate the picture’s aesthetic dimensions. This was a technical image that could justly be contemplated by the artist. In its luminous gradations and multitude of forms was visual poetry, if not heavenly associations. The foggy pleats posed a nest of mysteries, each opaque cloud-front begging speculation as to what lies beyond. (Modern astronomers see through such barriers by capturing radio waves or infrared light that penetrate the gas and dust.)

  Despite its nonuniformity—in bringing out faint details, stars and bright regions were grossly overexposed—Common’s photograph evinced the authority of a scientific document. Not only was it arguably more objective, but more acute, than the most detailed sketches. Although subtle distinctions in appearance were expected—the human retina and the dry plate have different color sensitivities—disputes over which of history’s drawings best matched Orion’s “true” face were effectively mooted by a single photographic frame. In 1887, popular science documentarian Agnes Clerke featured Common’s one-hour exposure as the frontispiece of her History of Astronomy During the Nineteenth Century. Photography, she declared, had “assumed the office of historiographer to the nebulae . . . [T]his one impression embodies a mass of facts hardly to be compassed by months of labour with the pencil.”

  In 1885, again itching for more aperture, Common sold his three-foot reflector to British amateur astronomer Edward Crossley for the present-day sum of two million dollars. Common next embarked on a tortuous quest to construct his own five-foot reflector. A near-plunge from the elevated scaffold persuaded him to reconfigure the partly completed instrument with the eyepiece closer to the ground. Five years in the making, the finished product was mediocre, both mechanically and optically. After taking a few photographs of Orion and other nebulae, Common abandoned his creation to develop telescopic gunsights for the Royal Navy. (The three-foot telescope was donated by Crossley to California’s Lick Observatory in 1895; the five-foot went to Harvard in 1904 after Common’s death.)

  Andrew Common’s immediate successor in the British “grand amateur” tradition was Isaac Roberts, a Welsh farmer’s son who made his fortune in the Liverpool building trade. Inspired by Common’s celebrated image of Orion, Roberts purchased a twenty-inch photographic reflector, and in March 1885, affixed it to a superior equatorial mount. The telescope itself was the camera: within the tube, a photographic plate holder replaced the standard secondary mirror that deflects light through an eyepiece. Although Common’s instruments were larger, the twenty-inch tracked celestial objects far more precisely. Immediately Roberts was taking time exposures up to an hour’s duration; before long, three- and four-hour exposures were routine.

  Isaac Roberts.

  Among Roberts’s initial targets was the Pleiades, a loose cluster of stars famously poeticized in Tennyson’s “Locksley Hall” as a “swarm of fireflies tangled in a silver braid.” In 1859, the keen-eyed comet hunter Wilhelm Tempel perceived the metaphorical braid in the form of a tenuous veil overlying the stars. The full extent of the Pleiades nebulosity appeared in a series of striking photographs by Roberts in 1886, described memorably by Agnes Clerke: “‘Streamers and fleecy masses’ extend from star to star. Nebulae in wings and trains, nebulae in patches, wisps, and streaks, seem to fill the system, as clouds choke a mountain valley.”

  The twenty-inch photographic reflector telescope of Isaac Roberts.

  That same year, Roberts produced an hour-long exposure of the Orion Nebula that revealed subtle swirls of nebulosity in regions long assumed to be voids. And on the original negative, the nebula’s central region, bleached out in Common’s now-famous picture, resolved itself into “cloud-like, curdling masses.” Three years later, in 1889, Roberts presented to the Royal Astronomical Society seven more plates of Orion, ranging in exposure time from five seconds to almost three-and-a-half hours. The short exposures resembled Herschel’s, Rosse’s, and Bond’s drawings. But with each succeeding jump in duration, Orion’s boundaries swelled and its substance thickened. Once-ghostly streamers jelled into luminous tentacles that ensnared neighboring clouds of matter. What cosmic explorers had taken for an islet within the ocean of space was, in these photographs, a celestial continent.

  The Pleiades, in a photograph taken by Isaac Roberts in October 1886.

  Roberts closed his presentation with a nod to his visual predecessors, while simultaneously elbowing them aside: “[W]e ought, with all gratitude, to admire the patient, long-suffering endurance of those martyrs to science, who during the freezing nights of many successive winters plotted, with pencil in benumbed fingers, the crude outlines which have been handed down to us as correct drawings of this wonderful nebula, which we can now depict during four hours of clear sky with far greater accuracy than is possible by the best hand-work in a lifetime.”

  The Orion Nebula, in an eighty-one-minute exposure by Isaac Roberts on December 24, 1888.

  Among the night-sky wonders, the Orion Nebula shares top billing with its more northerly counterpart in the constellation of Andromeda. More than five times the span of the full Moon, the Andromeda Nebula is seen as an elongated luminance, bright near the hub, feathering to invisibility in the outskirts. (Having aspired to astronomy as a youngster in light-bound New Jersey, I didn’t see the Andromeda Nebula—or the Milky Way, for that matter—until a family vacation took me to the inky skies of Colorado.) Andromeda’s ghostly presence was noted by tenth-century Persian astronomer Abd-al-Rahman al-Sufi, and it appears on a Dutch sky chart from the year 1500. Galileo’s contemporary Simon Marius first observed the object through a telescope in 1612, aptly describing its pale glow as that of “a candle shining through horn.” In the 1700s, French comet hunter Charles Messier included the Andromeda Nebula as the thirty-firs
t entry in his catalog of diffuse celestial objects; hence, its oft-used alias, M31.

  As with the Orion Nebula, historical depictions of Andromeda range widely. Written accounts convey more a sense of befuddlement than agreement about its appearance and nature. Messier saw it as “two luminous cones or pyramids opposite at their base . . . without any appearance of stars.” Observing with Harvard’s Great Refractor in 1847, George Bond drew attention to a pair of nearly parallel dark lanes that stretch lengthwise along the nebulosity. Deep-sky expert Reverend T. W. Webb considered all the available data as of 1882 and concluded that the Andromeda Nebula was “a mystery never in all probability to be penetrated by man.” The reverend’s lack of faith in the scientific enterprise proved to be misplaced.

  There were audible gasps from the audience when Isaac Roberts projected his three-hour exposure of the Andromeda Nebula before the Royal Astronomical Society on December 14, 1888. Herbert Hall Turner, Savilian Professor of Astronomy at Oxford, called the sight a “revelation,” while Norman Lockyer, longtime editor of the scientific journal Nature, judged the image “one of the most valuable photographs which I suppose has ever been taken.” What the attendees saw in this expansive depiction of the Andromeda Nebula was not its accustomed amorphous glow, but a wholly new structure with profound connotations.

  A celestial photograph is, by nature, a two-dimensional record of three-dimensional reality: it depicts an object’s form as though flattened onto the illusory plane of the sky. Informed by visual cues in the image, the human brain reconstructs the sensation of depth and physical bulk—at least according to one’s preconceptions and real-world experience. (How easily the brain can be fooled by optical illusions.) The Andromeda in Isaac Roberts’s photograph virtually exploded into the third-dimension to reveal a series of concentric, highly foreshortened annuli of diffuse matter, all tilted at an extreme angle to the line of sight. George Bond’s dark lanes, here vividly seen, were gaps between the adjacent rings of matter. No doubt every astronomer in the room sailed their mind’s eye into space to picture Andromeda from the face-on perspective: a majestic, multiarmed spiral, like Lord Rosse’s Whirpool Nebula and some fourteen others seen through his Leviathan telescope.