by Sarah Dry
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How did Piazzi Smyth, in practice, set out to disentangle the myriad forces that together made up the unity of Nature? The first, elusive glimpse of the peak, revealed through the clouds, pointed the way. His objective was to get as high up the mountain as was possible and locate a place on which an observatory could be built. A crew of twenty porters and twenty mules helped him get there, once the cumbersome boxes he’d brought on the ship had been broken down into parcels more suitable for carrying up a jagged volcano than stowing on a ship. By one o’clock on the first day of climbing, the expedition reached over 7,000 feet. “Light and heat revel everywhere,” marveled Piazzi Smyth. “There is no need of volcanic assistance.”17 They reached the top of the mountain’s intermediate peak, Guajara, as day fell. The porters hastily stashed their loads and sped back down the mountain to spend the night at a more reasonable altitude. Piazzi Smyth and the rest of the small party of foreigners stayed at the summit. Piazzi Smyth exulted that he was, “within twenty-four days of leaving England, bivouacking at a height of nearly 9000 feet, on a mountain only 28 degrees from the Equator.”18
On the way up the mountain, they hiked through the discrete layer of clouds he’d seen from below on the ship. The layer floated like an atmospheric sea, above which the peaks of Tenerife and nearby La Palma jutted, secondary islands emerging not from the liquid water of the ocean but from the condensed water droplets that formed the cloudscape. Those clouds were persistent and uniform, and they stretched as far as the eye could see. They were a literal and a metaphorical boundary. Piazzi Smyth called it “that great plain of vapour floating in mid-air at a height of 4000 feet.” It was a “separator of many things. Beneath were a moist atmosphere, fruits, and gardens, and the abodes of men; above, an air inconceivably dry, in which the bare bones of the great mountain lay oxidizing in all variety of brilliant colours, in the light of the sun by day, and stars unnumerable at night.”19 Above, too, was the realm in which lay the astronomical justification for his trip, the vindication of Newton and a sharpness of celestial vision otherwise inconceivable.
What clouds were and to which landscapes they belonged was an open question. Howard had altered the form and content of meteorology when he had suggested that clouds were neither endlessly variable nor unclassifiable. But many questions remained, not least whether clouds were, like living species, indigenous to certain places or whether they were more general, universal features to be found throughout the globe. When Piazzi Smyth went up the mountain, the clouds at Tenerife were noteworthy for their difference from English clouds, but they were also, it was to be hoped, potentially able to be reduced to universal laws just as the changing magnetic readings taken during the Magnetic Crusade had been.
The intensity of the light changed the nature of time on the mountain. Piazzi Smyth could see so much more in a single day or night than he could ever see in lower realms that he was able to achieve an astonishing amount of observing. “The day wears apace,” explained Piazzi Smyth, “and most luxuriantly in so pellucid an atmosphere, lit up by the rays of a vertical sun, undiminished by any aerial impurity. Each moment on a day of this sort is worth hours on any other; we look at everything far and near, see it as it were face to face, and gain a higher idea of the glorious creation in which we live.” Color acquired extraordinary depth: “glorious cadmium,” “the richest tint of red-orange,” “lemon-yellow,” “powerful rose-pink” and, finally, the “deep blue sky above.”20
Much work was needed to transform the light into a useable scientific tool. Piazzi Smyth spent about a month camped at 9,000 feet before frustration with persistent dust sent him higher, to the appropriately named Alta Vista, at 10,700 feet. He set about doing what he had avoided doing at Guajara, transporting the “great Pattinson equatorial telescope,” which required “straining every nerve to accomplish the main feature of the expedition—viz. to place the largest telescope on the highest available part of the mountain.”21 Around the inner “telescope square,” a group of local men and some crew members from Stephenson’s ship labored to create a group of five rooms (with roofs, Piazzi Smyth noted proudly) and a veranda which offered some protection from the elements.
Down to its bones, the place was hybrid. The walls were built of rocks from the summit, to which were added felt wall coverings and supporting timbers made by young poles of fir brought from Tenerife and glass plates, shutters, and door hinges brought all the way from Edinburgh. Plain nails were plentiful on the island, but “good screw nails,” noted Piazzi Smyth, “seem to be bound up with the march of Anglo-Saxon civilization.”22 It was a joke that showed how much the success of the astronomical experiment depended on reproducing conditions back in Britain, down to the screws used to fix the instruments together.
It wasn’t easy. Most of the more than 500 pages of Piazzi Smyth’s book on the subject were spent describing just how hard it was. His tone was not querulous but full of amazement. “Some part or other of our photographical apparatus, for picturing the sun’s image,” he explained, “would every now and then begin to smoke and burn.” The eyepieces to the telescopes became dangerously heated, so they periodically had to stop in order to keep from burning themselves.23
It was worth it, though, and he knew it from the start. The difficulties were not avoidable. In fact, they were necessary. His first effortless, instantaneous gaze depended not only on the absence of vapor from the atmosphere but on an unbroken chain of labor and supervision (of men and materials) stretching from the summit back to Edinburgh and London. All of this hard work—the packing and portaging, the building and the training—become as transparent as the atmosphere the moment Piazzi Smyth put his eye to the telescope’s eyepiece. That is the magic trick behind this kind of scientific work—behind, in a sense, all scientific work: a great amount of work is applied to making a small bit of nature visible in a way it has never been visible before.
FIG. 3.4. Jessie Piazzi Smyth with telescope and sun hat at the peak of Alta Vista. Credit: Royal Observatory Edinburgh.
When Piazzi Smyth aimed his telescope at the sky and set his eye against the eyepiece, a singular line of vision stretched from there to the farthest star. He could see farther, much farther, than he (or anyone) had ever seen before. This is worth repeating: From his vantage on the mountaintop, armed with a powerful telescope, with the clear air stretching above him to the emptiness of space, Charles Piazzi Smyth could see farther into the heavens than anyone had ever seen before. In the first night of observing on the summit, he transcended the viewing records of a lifetime. Pairs of stars, normally blurred and indistinct, leapt out at him. Even the faintest stars, of sixteenth magnitude, were easily visible. He quickly ran out of astronomical tests with which to gauge the extent of the vision he’d acquired.24
Having proven the practicality and desirability of mountaintop astronomy, Piazzi Smyth set about taking observations that would contribute to the exciting developments in physical astronomy, in showing what the stars and the planets were, rather than just where. The instruments he’d so laboriously transported offered the potential to do what Humboldt had urged and begin to tease apart the physical phenomena that together made up our impressions of both heaven and earth. What caused the spots on the sun to change, and by what cycle did they do so? What were the red prominences that shot out from the sun, visible during eclipses but presumably present all the time? What was the nature of the double stars, and how did their rotation change over time? What patterns controlled the tides, the earth’s weather, its magnetic field?
There were so many questions. It was impossible to answer them all. But the fact that they were being asked at all indicated how much had changed in the way people thought about the heavens and the earth. New and improved instruments made it possible to “see” invisible physical phenomena for the first time. Increasingly powerful telescopes were able to gather more light and resolve finer detail. Photography was put to astronomical uses almost a
s soon as it was invented, when Louis Daguerre pointed a camera at the moon in 1839, a feat repeated with more success the next year by John William Draper, who devised a way to track the moon during the long exposure. Images of the sun followed in the 1840s, and the first star, Vega, submitted to photography in 1850. Most influential of all was the spectroscope, a device that made light an experimental tool capable of diagnosing the contents of distant atmospheres. It provided yet more evidence for the unity of nature, proving that the same elements were present on earth and in the heavens.
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The distinctive array of colors produced by the diffraction of light had been observed for centuries. Leonardo da Vinci had noted “rainbow colors” around the edges of air bubbles in a glass of water. Isaac Newton had introduced himself to scientific society when he’d demonstrated that the oblong of light produced by a prism of sufficiently clear glass was made up of colors that could not be further modified. He coined the term spectrum—playing on its double meaning as both a ghostly image and something which is seen—to describe the rainbow of colors which were refracted to different degrees by the prism. It was Newton who divided the spectrum into the seven colors, a system which dominated the way people saw the spectrum throughout the eighteenth century. It was only in 1802 that William Hyde Wollaston, a physician with an interest in light, observed the spectrum through a very narrow slit and noticed for the first time that atop the spray of colors lay a series of black lines. He made an initial attempt to map these lines, identifying the five most prominent, and labeled them with the corresponding capital letters A through E. Acting independently, in 1824 Joseph von Fraunhofer, a German glassmaker working with high-quality prisms (and consequently more interested in what the spectrum could reveal about the purity of the glass than vice versa), added considerably to the map, assigning unique numbers to more than 500 lines.
Seeing the spectrum was no simple matter. No one knew how many lines there might be. The closer anyone looked, the more seemed to appear. Still less certain was what caused them. This made it that much harder to know when to trust one’s eyes. A further complication was the difficulty of translating what was seen into something that could be represented graphically. Piazzi Smyth, trained from an early age in just these skills, was exquisitely attuned to just how much skill was required to accurately represent astronomical phenomena with techniques such as John Herschel’s use of “a fine camel’s hair brush” and successive washes of varnish to draw stars. A faithful imitation of such tricky phenomena to record as the Aurora Borealis, a cloud of nebular gas, or the tail of a comet could only be obtained by “correctness of eye, facility of hand, and a due appreciation of the subject.”25 The spectrum, with its spray of lines of varying strength, which seemed to come and go, was especially hard to capture.
FIG. 3.5. Spectra of the sun observed at various altitudes and times of day from Charles Piazzi Smyth’s report on the Tenerife expedition. The bottom reading was taken when the sun was setting.
Charles Babbage, impresario of science and decrier of British decline in relation to the French and the Germans, not only recognized that vision was a skill that had to be acquired, but saw that it had national repercussions. In his Reflexions on the Decline of Science in England, he recounted how Herschel had warned him how difficult it was to see spectral lines of the sun. He could sit in front of a spectroscope through which the solar lines were visible, said Herschel, but Babbage would not be able to see them until he had been told “how to see them,” at which point, and only at which point, he would then be able to see them. After having seen them, Herschel told Babbage, you will wonder how you could have missed them and will never be able to look at a spectrum again without seeing them. And so it was.26 Without good systems for training observers, Babbage concluded, British astronomy could not compete on the international stage.
The drive initially was to map more and more lines. Soon, it became clear that the number of lines visible depended not only on the size of the telescope or the clarity of the prism, but on the time of day and direction in which the telescope was pointed. In 1833, the physicist David Brewster announced the results of a multi-year project. Not only had he observed the spectrum at a resolution some four times greater than what Fraunhofer had achieved, but he had observed the spectrum at different times of the year, under different meteorological conditions, and with the sun at varying angles in the sky. With his observations, Brewster was able to move toward the Humboldtian dream of disaggregating phenomena in order to understand them better. In 1856, when Piazzi Smyth embarked for Tenerife, it still remained very unclear what the cause of these lines were and where they originated.
And so, in addition to his nighttime observations of the stars, Piazzi Smyth used the spectroscopes he’d brought to study the characteristic lines that appeared when sunlight was observed passing first through a slit and then through a prism. The metropolitan scientists, tethered to their urban observatories, wanted to know if lines appeared or disappeared when Piazzi Smyth looked through the spectrum on the mountaintop. Did they look different at sunset or sunrise?
Here the mountain came into its own as a tool for separating the earth’s atmosphere from the sun’s. Atop the peak, observing sunlight with his spectroscopic apparatus, itself a hybrid of telescope, prism, and a slit that spread the spectrum and thereby revealed the lines, Piazzi Smyth was uniquely positioned to help solve the question. Pointing the spectroscope at the sun at midday, he was closer to the sun’s atmosphere than any other similarly equipped observer on the planet. So too, as he tracked the sun on its ascent and descent, at dawn and sunset, when it hovered just at the horizon, he had access to a thicker portion of the atmosphere than anyone else on the planet.
As with the distant stars, so with the sun, what Piazzi Smyth saw from his privileged position seemed effortlessly dispositive, unmistakably clear. As he watched the setting sun through the apparatus, he saw the number of lines grow visibly before his eyes. This was evidence that at least some of the lines were earthly in origin, a visible marker of some invisible substance which increased as the section of the earth’s atmosphere he was looking through thickened. This meant that the spectrum revealed by any spectroscopic apparatus pointed at the sky was always a hybrid, a representation of the atmospheric contents of both the sun and the earth. This complicated the quest to identify the contents of something so distant as the sun with little more than a special piece of glass. But Piazzi Smyth’s observations on Tenerife also showed that the spectroscope, used in the right location and with the right techniques, could be a tool for revealing the differences between those contents and for plumbing the atmospheric reaches of the earth itself.
What caused the lines that grew before his eyes, Piazzi Smyth did not hazard to guess. Nor did he wonder, at that moment, about the precise details of their variation, whether the lines ebbed and grew solely due to the amount of atmosphere through which he was observing or whether the internal changes of the earth’s atmosphere itself affected the pattern he saw. Those thoughts would come later. At the time, the observations formed just one part of the dozens he was making, using every waking moment on the mountain.
We know how Piazzi Smyth felt as he craned his neck to look up at the summit of Tenerife because he wrote a book about his experience. His great subject was the act of observation itself, and hidden in every record of the outside world that he made over a lifetime of watching was a record of Piazzi Smyth, the observer. Convinced of the advantages of photography for scientific observation, Piazzi Smyth spent “all spare moments” on the mountain with a camera he had gotten at the last minute, making images of the surrounding landscape, the unusual flora, and the work of scientific observation itself. The description I have recounted takes up about five pages in Teneriffe, An Astronomer’s Experiment: Or, Specialities of a Residence Above the Clouds, which Piazzi Smyth published in 1858. That book provides a lengthy description of the whole voyage in language that is c
olorful without being florid. It also contains a set of twenty stereo-photographs taken by Piazzi Smyth on the expedition, the first time such a set of photographs had been included in a printed volume.
In his preface to the book, Piazzi Smyth explained the reason he had taken such care and effort to make and print his doubled photographs: They possessed what he called a “necessary faithfulness.” While single photographs may contain smudges or artifacts, the stereo-photograph can serve as its own correction. A comparison of the two images will reveal what is real, and what is merely accidental. A further degree of veracity is achieved when the images are combined stereoscopically to produce the impression of distance or solidity, normally the purview only of great painters. The doubled images themselves do a double duty, producing scientific accuracy and the kind of aesthetic “effects” normally produced by artists.
Piazzi Smyth was always doing science and watching himself (and others) do science. He recorded natural phenomena and the process of recording natural phenomena with the same level of interest. This meant that he sketched the boat (itself a scientific instrument of exploration) upon which he traveled and even took photographs of the crew in the difficult setting. It meant that he kept a detailed journal of the expedition (a long-standing dual form of registration—both of the natural world and of the perceptions of the observer of the natural world). It meant that he carefully observed the sailors from his ship who had transformed themselves (with his help) into disciplined observers themselves. He included a photograph of the second mate of the ship in the act of taking a temperature measurement. In one hand is the chronometer he used to time the observation; in the other is the notebook in which he recorded it. The image, like the others in the book, appears in stereo—a further doubling of an already doubled act of observation: Piazzi Smyth watching the second mate watching the temperature. Similarly, the act of scientific observation was itself carefully watched here, not only by Piazzi Smyth but also by the readers of his popular and his official accounts. Science, an act of observation, required observation itself to be regulated.
