Starlight Detectives Page 7
Of a subsequent Whipple–Bond daguerreotype of the quarter Moon, presented at a meeting of the British Association for the Advancement of Science, a reporter lavished fulsome praise: “Fringes of darkness casting themselves off behind the peaks and summits of silver, rounded waves of shadow, filling up cavities in the form of hollow cups as abysses in the midst of this strange surface; triangles of jet, shooting forth like twigs under luminous spots, brilliant as diamonds—this is what the telescope displayed. In the photographic image produced by Dr. Bond, all these details are revealed to the eye. Everything there is so completely and faithfully reproduced, that by the aid of a magnifying glass we perceive new objects, minute details, that had escaped the sight. . . . It is impossible to calculate the services that photography is called to render to astronomy.”
On March 22, 1851, Whipple and George Bond took a daguerreotype of Jupiter that captured two of the planet’s broad equatorial belts. Bond was surprised to find that the exposure time required to imprint Jupiter on the plate was nearly identical to that needed for the Moon. He had predicted a much longer exposure. Jupiter is just over five times farther than the Moon, that multiple of distance, in effect, diluting the light emission received from Jupiter’s surface. Because both the Moon and Jupiter shine by reflected sunlight, a patch of Jovian surface should appear about twenty-seven times dimmer than the same-size patch on the Moon. (Light intensity diminishes with the square of the distance.) Hence, Bond was mistaken in his expectation that a successful exposure of Jupiter would be of longer duration than a lunar exposure. He drew the conclusion, later confirmed, that Jupiter’s surface is much more reflective than the Moon’s, offsetting the dimming effect of distance. Bond’s observation of this phenomenon is the first scientific result credited to celestial photography. (A full report was published in 1861.)
Daguerreotype of the moon taken with the Harvard refractor by Whipple and the Bonds in 1852. A similar photograph created a sensation at the 1851 Crystal Palace exhibition in London.
If William Cranch Bond had a sentimental favorite among the early pictures taken from Cambridge, it might have been the daguerreotype he took with Whipple of the partial solar eclipse of July 28, 1851, some forty-five years after the total eclipse that had sparked his passion for astronomy. George Bond, then twenty-six, was touring the observatories of Europe and observed the July 28 eclipse from a remote village in Sweden, which, unlike Cambridge, lay along the geographic path of totality. George’s letter to his father must have awakened the elder Bond’s youthful memories of the 1806 eclipse: “The change which takes place in less than a tenth of a second, so entirely alters the scene, that the second which precedes total obscuration gives one no idea of what is to follow. . . . What I then saw, it is utterly beyond my power of language adequately to express. The corona of white light which encircled the dark body of the Moon, resembled the aureola, or glory, by which painters designate the person of the Savior, its radiance extending from the circumference to a distance equal to about half of the Sun’s diameter. . . . How shall I attempt to describe . . . these flame-like protuberances projecting from the inner edges of the corona? . . . [The eclipse] was surpassingly beautiful—the most sublime of all that we are permitted to see of the material creation.” Lacking a camera, George Bond afterward sketched the eclipse from memory. The daguerreotypist Berkowski, from Königsberg, obtained an acclaimed photograph of the event that clearly depicted Bond’s “flame-like protuberances.”
Harvard’s experiments in celestial photography continued through April 24, 1852, culminating in a superb twenty-second daguerreotype of the crescent Moon. Then the observatory record is silent for five years on the subject of nighttime photography. (There is a mention in 1853 about a failed attempt to take pictures of sunspots.) Evidently, Bond and Whipple concluded that they had accomplished pretty much all they could with the ultraslow daguerreotype process and with the telescope’s lamentable Munich friction-drive. It was time to wait until technology caught up to their aspirations.
Whipple’s youthful enthusiasm remained high as his initial foray into celestial imaging drew to a close. His photographer’s imagination was stirred by the sight of his own Moon pictures, each a crisply defined, two-inch miniature of a familiar, yet alien, world. Just twenty-six, he looked ahead to a time when technological improvements might permit a sequence of lunar photographs “taken as old Sol lights up peak after peak, shining first on this side, then on that, and as these shadows sweep through her immense cavernous valleys, then as the full blaze of the sun penetrates those awfully deep yawning gulfs.”
In fact, Whipple’s vision would be realized within the decade, the result of a new photochemical process already making the rounds in England.
Chapter 5
THE MAN WITH THE OIL-CAN
In bringing before the Association the present Report it will be only necessary, after referring briefly to the labours of others, to confine myself to an account of my personal experience; for, although other observers have occasionally made experiments in Celestial Photography, there has not been any systematic pursuit of this branch of Astronomy in England, except in my Observatory.
—Warren De La Rue, Report to the British Association for the Advancement of Science, September 1859
THE GREAT EXHIBITION AT LONDON’S CRYSTAL PALACE in 1851 was a showcase of humanity’s industrial and artistic achievements. Some thirteen thousand displays filled a sprawling cast-iron and glass greenhouse of almost a million square feet. Giant steam engines, Jacquard looms, and power reapers sat imposingly amid samples of silk, furniture, Colt revolvers, even the Koh-i-Noor diamond. More than six million visitors paraded through the vast hall, among live elms, marble statues, and celebratory fountains, all to the reverberant backdrop of the world’s largest pipe organ. Among the throng of attendees was Harvard’s George Bond, then twenty-six, who enthused in his diary on June 4, 1851, “Anyone who is not satisfied would better find another world to live in. . . . The Arabian Nights are thrown far into the shade by the realities of the Crystal Palace.”
Warren De La Rue.
Bond’s brother, Richard, was there to demonstrate his astronomical recorder: a rotating-drum chart-plotter that time-stamped meridian passages of stars at the observer’s press of a button. Also in attendance, John Whipple, showcasing the pioneering daguerreotype of the Moon that he and the Bonds had taken through Harvard’s Great Refractor. The lunar photograph was one of only three American exhibits to receive the highest award for excellence. In the eyes of wonderstruck viewers, a celestial body had miraculously been brought down to Earth for close inspection.
Down the building’s main avenue, positioned between Cruchley’s large-scale map of England and Armstrong’s specimens of illustrated musical printing, was an especial admirer of Whipple and Bond’s daguerreotype. Warren De La Rue, partner in his father’s stationery firm, was showcasing his own creation: an envelope-making machine. The device could fold and glue twenty-seven hundred envelopes per hour, as many as an experienced worker could complete in a day. Educated in Paris, the affable De La Rue quickly distinguished himself as a self-taught mechanical wizard, in the mold of William Cranch Bond. “I am the man with the oil-can,” he once remarked, characterizing his skill at practical problem solving. That and his keen business sense made him a valuable asset to his father’s company, which he joined upon leaving Paris at the outbreak of the Revolution of 1830.
De La Rue’s outside interests ranged among the technical disciplines, starting with electrochemistry. A founding member of the Chemical Society of London, he published his first research paper, on the chemistry of batteries, in 1836 when he was just twenty-one. He subsequently studied at the Royal College of Chemistry under the prominent German organic chemist August Wilhelm von Hofmann. De La Rue’s chemical studies brought him to the attention of the Royal Society, which elected him Fellow in 1850. But by then, he had virtually abandoned chemistry in favor of a new pursuit: astronomy.
In the lat
e 1830s, De La Rue had been tasked with the design of a production facility for white lead, which was to be used in the manufacture of the company’s popular line of playing cards. He sought the advice of industrialist James Nasmyth, inventor of the steam-driven hammer and pile driver. An engineering prodigy, Nasmyth had built his own steam engine in 1825 at age seventeen, and two years later, created a working, eight-passenger “road steam-carriage”—a primitive automobile. That same year, he made a six-inch reflector telescope, the first in a series of progressively larger and more sophisticated instruments that he used to study the topography of the Moon. By the time De La Rue arrived at his doorstep in 1840, Nasmyth was an irrepressible champion of astronomy: “If I were asked what course of practice was the best to instill the finest taste for refined mechanical work, I should say, set to and make for yourself from first to last a reflecting telescope.”
Nasmyth invited De La Rue to watch the casting of his thirteen-inch telescope mirror from molten speculum metal (an alloy of tin, copper, and arsenic). Intrigued, De La Rue returned regularly to observe the grinding and polishing of the mirror, and several times more to watch the fabrication of the telescope’s mechanical mount. By the late 1840s, every fiber of De La Rue’s mechanical, scientific, and artistic talents was being channeled toward astronomy and its instruments. He commissioned Nasmyth to cast him a thirteen-inch speculum metal disk, which he ground and polished to its proper concave shape with a machine of his own design. The machine produced a more accurate concavity than the best existing devices, and became the subject of De La Rue’s first publication in astronomy. In 1849, De La Rue set up the completed telescope in the garden of his home in Canon-bury outside London. His skillful drawing of Saturn’s rings was exhibited to acclaim at the January 1851 meeting of the Royal Astronomical Society, which elected him to fellowship a few months later.
De La Rue recalled navigating his way through the Crystal Palace in 1851 to the much-heralded lunar daguerreotype of Whipple and the Bonds. Although by then a seasoned observer, with the Moon’s terrain securely mapped into his memory, he faced the picture as if seeing that celestial body for the first time. The dusky maria, sharp-rimmed craters, and vertiginous mountain ranges were all there, captured with stunning sharpness. Here was a picture, De La Rue realized, whose fidelity far surpassed anything he could generate by hand, even with his considerable drafting skills. This was no mere representation of the Moon; it was the Moon, as it had appeared on March 14, 1851, chemically frozen in time. In the reserved Victorian vernacular of his day, De La Rue admitted to being “charmed” by the picture. However, his subsequent burst of activity suggests a much more profound impact. The advancement of celestial photography posed precisely the sort of cross-disciplinary challenge that tugged at De La Rue’s engineering, astronomical, chemical, and artistic sensibilities. The only question was how best to proceed.
Drawing of the planet Saturn by Warren De La Rue, 1856.
De La Rue was probably unaware at the time, but his future pathway was being laid during the last days of the Great Exhibition. The hastily erected display by London-based sculptor Frederick Scott Archer was too late to appear in the Exhibition’s official catalog. The contents of the display were neither carvings nor bronzes, as one might expect from Archer’s nominal line of work. They were photographs: remarkably vivid images, not on paper, not on metal, but on sheets of glass.
The first decade of photography, the 1840s, was a contest for dominance between two rival methods: the daguerreotype and Talbot’s calotype. Both processes employed light-sensitive silver compounds, required chemical development of the latent image, used hypo to fix the image, and rendered scenes without their natural colors (shades of gold-tinted gray for the daguerreotype, shades of mellow brown for the calotype). Beyond these basic commonalities, each process had its advantages and disadvantages—technical, aesthetic, and legal.
The daguerreotype system produces a direct positive image, although reversed left to right. The clarity of the daguerreotype image surpasses that of the calotype, recording a measure of detail that appears remarkable even today. However, the metal plate has a mirrorlike finish, restricting visibility of the image to a narrow range of viewing angles. Also a single exposure produces a unique, practically irreproducible picture. The only way to make a copy is to take a picture of the daguerreotype itself. This is not an easy proposition, as the plate’s reflectivity makes it difficult to illuminate properly.
Like the daguerreotype, the calotype requires a great deal of advance preparation. A sheet of high-quality writing paper is dipped into salt water, brushed on one side with silver nitrate, and dried. The process is repeated several times until the sheet has absorbed a sufficient amount of the chemical. It proved difficult to produce a sheet with uniform sensitivity and to maintain comparable sensitivity levels among different sheets.
The calotype technique generates a matte-finish, paper negative with the correct left-right orientation and no viewing angle restriction. Early calotypes looked murky compared to daguerreotypes, their resolution limited by the fibrous texture of the paper. Given their relatively weak light sensitivity, exposure times far exceeded those of daguerreotypes. On the other hand, any number of positive contact prints can be easily generated from a single calotype negative. Yet even after it was improved, the calotype found only a limited market, in part because of Talbot’s vigorous protection of his patent.
Neither the daguerreotype nor the calotype were astronomy-friendly. In fact, they were downright hostile. Even after significant improvements, both technologies required long time exposures at the telescope, during which all the demons of man, machinery, and nature worked their mischief. The longer the camera shutter was open, the greater the risk of failure. That any progress was made in telescopic photography during the 1840s and early 1850s is remarkable in retrospect. The accomplishments, such as they were, speak to the perseverance of astronomers and their photographic allies in the face of fatigue, serial failures, and capricious weather. The frustration Whipple and the Bonds had endured to obtain their celebrated lunar daguerreotype was invisible to spectators at the Great Exhibition, who reflected only on the picture’s rugged beauty and perhaps its implications for the future of scientific and artistic representation. Few at the time, except the practitioners themselves, expected that the astronomical daguerreotype had reached its zenith. The vaunted Moon picture represents what could be done despite the technology, not because of it. Until exposure times were shortened and telescope drives improved, astronomers would remain hostage to every flutter of the air and lurch of a drive gear. By the early 1850s, the effort to photograph the heavens had reached a technological impasse.
From the start, astronomers affixed cameras to their telescopes in an attempt to generate accurate, objective, permanent pictures of celestial objects—essentially, to unhitch the depiction of the cosmos from the subjective eye and hand. Celestial photography places strict demands on the imaging technology, critical aspects of which must be optimized for the particular challenges involved. Of course, the ability to accurately render detail is paramount. Clarity of the image is compromised by turbulence in Earth’s atmosphere, as well as by vibrations of the telescope, effects amplified by the magnifying power of the instrument. By starting with a highest-resolution photographic process—in the 1840s, this was the daguerreotype—the astronomer mitigates, in part, the blurring of images by external agents.
Another major consideration in celestial photography is the faintness of most of the target objects. A telescope operates as an optical funnel: it collects cosmic light over the entirety of its objective lens or reflector, and focuses that energy into a progressively narrow beam that enters the eye or the camera. That’s why we are able to perceive heavenly bodies that are invisible to the naked eye. The telescope, in essence, expands the pupil of the eye from its nominal quarter-inch to, say, six inches or six feet—whatever the telescope’s aperture. The eye has no means to store the light emerging from t
he telescope; the retina is a real-time sensor: when stimulated by a pattern of light, it fires off a stream of electrical signals through the optic nerve that the brain synthesizes into an image. Thus, the eye is our visual portal to the world; our brain does the actual seeing.
Viewed through the eyepiece of a telescope, a star appears, not as a composed, fiery speck, but a turbulent bead of light, its edges erupting in spikes, like a cat trying to claw its way out of a luminescent sack. The image goes in and out of focus and flits randomly about the center of the field of view. The eye is adept at tracking these frenetic changes in appearance, ever ready to behold the rare instants when the image snaps into a momentary state of calm and sublime clarity. (Even seasoned observers can’t suppress a “Wow!” whenever this occurs.)
A camera is fundamentally different from the eye: it accumulates light as long as the shutter is open, storing the luminous energy in chemical form on the photographic plate. Every succeeding second of exposure reinforces the overall definition of the image, rendering it increasingly vivid as time proceeds. In theory, at least. The camera does not distinguish between intended aspects of an exposure—the way the object is supposed to look—and unintended distortions that afflict the photographic operation. If the telescope vibrates or shifts during the exposure, any newly arrived photons of light stray from the spot on the photographic plate where their predecessors had fallen. The result is an ill-defined disk of starlight, or the planet Saturn with a diffuse, bulging waistline instead of a delicate brace of rings. Everything is recorded, for good or ill. The camera is all-seeing, yet blind to the photographer’s intent.