by Sarah Dry
FIG. 3.6. Stereo-photograph image of ship’s mate making observations, taken by Charles Piazzi Smyth. Credit: Royal Observatory Edinburgh.
FIG. 3.7. Title page to Charles Piazzi Smyth’s official report of his expedition to Tenerife, with a stereo-photograph by him of a model of the peak by James Nasmyth.
FIG. 3.8. The Alta Vista Observatory, where a series of rough buildings formed a “telescope square,” in a stereo-photograph by Charles Piazzi Smyth. Credit: Royal Observatory Edinburgh.
The two photographs Piazzi Smyth chose to include in his official report were both images of the summit of the mountain. The first was a stereoscopic portrait of something no one had seen, including Piazzi Smyth himself. It was a double photograph of a model of the summit made by the engineer and talented amateur astronomer James Nasmyth. Piazzi Smyth photographed the model, based on data collected by the expedition, from above, and printed it in stereo view, providing a pure image of what the crater would look like to those with perfect vision and a perfect, God’s-eye vantage point. The second photograph was a single image (made from an enlarged camera-copy) of the Alta Vista Observatory, also taken from above. This view was a “real” view in the sense that Piazzi Smyth had climbed up a nearby peak from which he was able to look down on the observatory. The image shows the arm of the great telescope emerging from the “telegraph square,” the protected area around which the rudimentary observatory buildings had been erected. A flag can be seen extended in the wind.
This is an image of observation turned back on itself, a bold reminder to the Royal Society of just who had made the journey to the top of the mountain, and what he had accomplished there. If the purpose of the expedition had been to subtract the atmosphere from celestial observations, Piazzi Smyth had surely accomplished that. He’d also shown that every observation of even the most distant celestial objects was also an observation of the earth’s atmosphere. Finally, he’d understood that every outward observation was also, inevitably, an inwardly turned observation of the observer himself, of the self at the telescope’s eye.
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Everyone agreed that the expedition had been successful in proving the merit of mountaintop astronomy. Still, Piazzi Smyth managed somehow to wring defeat from the jaws of victory. A group of referees contacted by the Royal Society to judge the work before publication considered that Piazzi Smyth had strayed too far from his area of expertise in his geological and botanical observations, and refused to print the photographs which he had gone to such effort to take, citing cost of publication. Piazzi Smyth responded with a characteristic mixture of petulance and defiance. Within months he and Jessie had published their own account, including all of their photographs and observations. (Piazzi Smyth noted acerbically that his wife had managed to single-handedly print all three hundred photographs needed for the publication.) It was the first indication of what would prove a persistent problem for Piazzi Smyth—transgressing disciplinary boundaries in scientific circles and ruffling scientific feathers.
Piazzi Smyth’s restless mind made it hard for him to sit still, and within a few years of his return, he had found a new fascination that would prove even more troublesome. No longer was he fixated on proving the feasibility of observing the stars on top of a mountain. It was to another kind of mountain, a man-made one, to which he now turned his interest. Still fascinated with matters of visibility, the question he now posed was: Is it possible to see God if one looks hard—and measures carefully—enough?
The man-made mountain was the great Pyramid at Giza. It had long been the subject of polite European curiosity. Ever since Napoleon had visited at the end of the eighteenth century, Europeans had wondered how the pyramids had been built and by whom. The ratio between the perimeter of the base of the pyramid and its height, for example, was the same as that between the circumference of a circle and its radius, suggesting, to those who wished to believe it, that the ancient builders had understood pi. More intriguingly, but more complicatedly, in the 1850s a man called John Taylor suggested that the basic unit of construction of the pyramid was a cubit of twenty-five British inches long. The British inch, according to Taylor’s assessment, had an ancient pedigree. Not only that, Taylor inferred that this ancient British inch was also a sacred British inch, having formed the basis for the cubit which Noah had used to build his Ark and Moses his Tabernacle.
Piazzi Smyth read Taylor’s work and was so taken with his ideas that he applied his considerable writing skills to transforming Taylor’s obscure pamphlet into an exciting narrative dramatizing the Pyramid’s divine origins and the correspondingly divine lineage of the British inch. His book Our Inheritance in the Great Pyramid was the product of just six months of intense work, but it immediately found a large and enthusiastic audience of readers.27 In the light of competition with the French over the metric system, many were happy to look at the Pyramid along with Piazzi Smyth and see evidence for the divinity and antiquity of British metrical values. Soon, he and Jessie embarked for a self-financed journey to visit the Pyramids and measure them for themselves. If anyone could look hard enough and see well enough to find evidence of divinity stamped upon the stones, it was Piazzi Smyth.
FIG. 3.9. Charles Piazzi Smyth wearing an Egyptian fez. Credit: Royal Observatory Edinburgh.
The result of Charles and Jessie Piazzi Smyth’s stay at the Pyramid was thousands of measurements, made with, among other things, a “well-seasoned” rod from a pipe organ dating from the time of Queen Anne which would be less likely to warp in the intense heat, along with more modern mahogany sliding rods and ivory scales. The Piazzi Smyths observed the Pyramid as carefully as anyone, measuring its dimensions in as many directions and with as much precision as possible. At the same time, they made meteorological and astronomical observations much as they had atop the mountain at Tenerife. Piazzi Smyth proudly presented their results to the Royal Society in April 1866, a year after their return. He was rewarded for his efforts with a prize from the Society recognizing the “energy, self-sacrifice and skill” with which he had undertaken the work.28 It would seem that Piazzi Smyth had managed to bring the Pyramid into the realm of precise and incisive observations that he had triumphantly entered on top of Tenerife, and in so doing to read God’s intervention in the form of the structure. But while the quality of Piazzi Smyth’s measurements was never in doubt, his inferences from them ultimately went too far. Though it did not happen immediately, Piazzi Smyth’s reputation among his scientific peers was irredeemably damaged by his commitment to the idea of a sacred origin for the British inch.
The matter came to a head some ten years after his trip to the Pyramids, when Piazzi Smyth submitted a paper on the topic to the Royal Society in which he accused the renowned physicist James Clerk Maxwell of “serious error in an Egyptian allusion” Maxwell had made in a lecture to the British Association for the Advancement of Science.29 Piazzi Smyth’s paper was rejected as unsuitable, since it constituted what was viewed as an ad hominem attack on Maxwell. Piazzi Smyth’s ill-judged response was to resign his fellowship from the Royal Society. He did not expect his hasty offer to be accepted. Much to his surprise—and chagrin—it was. At the age of fifty-five, Piazzi Smyth had managed to exile himself from the Society that arbitrated the scientific world in which he had lived his entire life.
Though Piazzi Smyth’s friends were sympathetic, most felt he had brought the sad state of affairs upon himself. This poignant self-exile from the scientific community was perhaps one reason his next passionate engagement was with an instrument that freed him completely from the need to coordinate, communicate, or calibrate with others. The rainband spectroscope, as it was called, allowed him to do science alone. With it, he could look to the skies as an isolated individual and diagnose the entire contents of the atmosphere. What Piazzi Smyth hoped the spectroscope could do was something far more radical even than freeing him from the restricting embrace of the parliament of science. He hoped it could do
nothing less than help transform meteorology into a predictive, rather than a descriptive, science.
Keeping in mind that astronomy had long provided the template for a successful predictive science (even as a new emphasis on physical speculation had crept into it), anyone wishing to predict the weather on scientific lines was faced with the challenge of matching astronomy’s predictive power. This was, to put it mildly, not easy. In the 1870s, weather forecasting was within scientific circles possibly even more controversial than mystical theories of the Great Pyramid.
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Beginning in 1859, Admiral FitzRoy embarked upon what he called an experiment in weather forecasting. Using a telegraphic network that had been established merely to gather weather data into a system for generating and communicating weather forecasts, FitzRoy fashioned himself as a one-man meteorological band. He based his forecasts on observations of barometric pressure, temperature, and observed wind speed taken at a dozen locations around the country and transmitted to him via telegraph. Applying rules of thumb and his sailor’s intuition, within thirty minutes of receiving the information each morning he sent his forecasts back out over the network. The forecasts were immensely popular with local fishermen and sailors, as well as holiday-goers seeking sunshine. They were also controversial because they were so often incorrect. What good was a government science office, critics queried, that sent out erroneous predictions? Surely it did no good for the science of meteorology to be tainted by such inaccurate forecasts. Much to the discomfort of those scientists who winced at every inaccurate forecast, FitzRoy’s program received a great deal of attention from pundits and commentators who called him a “weather prophet” and made much of the humorous concatenation of scientific intent with the kind of fairground prognostications made by fortune-tellers. Things came to a sudden halt in 1865, when FitzRoy committed suicide for unknown reasons.
Following FitzRoy’s death, a committee formed of fellows of the Royal Society had been appointed to oversee the activity of the Met Office. They were unhappy to discover that the government office had been run as a personal meteorological fiefdom. FitzRoy had delegated little, and written down less. He used no scientific laws or mathematical equations, relying on his sailor’s intuition to produce forecasts by himself that he saw as augmenting rather than supplanting the weather wisdom of self-sufficient sailors. The Royal Committee members disapproved of what they considered government sponsorship of an act of individual prognostication akin to fortune-telling. Fearing liability for deaths at sea should the warnings be incorrect, and concerned to protect the reputation of the infant science of meteorology from charges of amateurism, they shut the storm warning program down.
Ten years later, the project of government-sponsored storm warnings in Britain remained locked in a stalemate. The fishermen and sailors along the coast missed the forecasts and wanted them reinstated. The committee of scientists still resisted, suggesting instead a round of internal, private forecasts. In the meantime, the Times had decided to go ahead and publish a weather map, the first of its kind, in the daily newspaper, beginning on April 1, 1875. Piazzi Smyth, for one, saw the resemblance between the government storm warnings and the folksy weather wisdom of old, but unlike the Royal Society fellows, it didn’t bother him in the least. He despaired of the bureaucracy and what he considered the unnecessary punctiliousness of the Royal Society committee members. He bemoaned those scientists who wanted to keep science for themselves, to claim a higher knowledge of phenomena—the movements of clouds, vapor, heat, and cold—which remained as unruly as the crowds that jostled on railway platforms on their way to seaside recreations. Excited by the novel technology of the rainband spectroscope, he saw an opportunity to circumvent the Royal Society committee and to bring weather forecasting back to the people. He recognized that the spectroscope could also sort out the links between terrestrial and heavenly phenomena at the same time, clarifying the unity of nature as well as the specific properties of earthly weather. Piazzi Smyth’s plan was to use a descendent of the spectroscopes that he had carried up the mountain at Tenerife, and deployed in a variety of exotic locations ever since; it would enable him to diagnose perhaps the most changeable, fluctatory phenomena on Earth—the skies above Britain. The weather embodied a deep paradox. It was made up of uniform molecules, and yet it was eternally in flux.
Spectroscopy had developed rapidly in the years following his Tenerife expedition. In 1859 Gustav Kirchhoff and Robert Bunsen had shown that the lines in the solar spectrum corresponded to chemical contents of the atmosphere of the sun, and Kirchhoff had gone further to correlate many of the Fraunhofer lines with specific metals. But there was still much confusion over what exactly caused the lines, whether some were the result of absorption in the sun’s atmosphere, some of absorption in the earth’s atmosphere, and some, possibly, owed their presence to a substance present in both. In 1860, David Brewster published a long paper, coauthored with J. H. Gladstone, in which he “majestically mapped the separation” between solar and terrestrial lines. The capstone of nearly three decades of work was the publication of a five-foot-long map of the solar spectrum in which he clearly distinguished between solar and atmospheric lines (without making any guess as to what might cause the lines). In it, Brewster and Gladstone referred to Piazzi Smyth’s Tenerife observations, noting that he “had an opportunity of analyzing the light of the sun when seen through a smaller amount of atmosphere than has fallen to the lot of any other investigator.”30 Despite their success in mapping the lines, an experiment designed by Brewster and Gladstone to reproduce the bands in the laboratory had failed and the origin of the atmospheric lines remained unexplained.
It took a Frenchman to clarify the matter. In 1865, Jules Janssen had stood on the balcony of his house on rue Labat in Montmartre, Paris, and aimed a spectroscope at the sky. Janssen was poor, and the earth’s atmosphere was a ready and free laboratory. Following up on the curious phenomena already identified by Brewster in 1833, he wanted to investigate the same lines that Piazzi Smyth had seen on the Tenerife mountain, and to try to pinpoint their origins to the earth or the sun’s atmosphere. Using a very good prism, he could see something that no one else had seen—the so-called dark bands were in fact crowds of dark lines, similar in structure to the more familiar, less variable lines of the spectrum that had been initially identified by Fraunhofer, some of which had been determined to be solar in origin. Janssen observed the lines at all times of day and noticed something further. The lines were especially strong when he observed sunlight at sunrise or sunset, but they never disappeared, even when he looked at the sun at high noon (a finding that contradicted Brewster’s earlier work). They must, he reasoned, be caused by something ever present in the earth’s atmosphere. (The effect at sunrise and sunset would be greater because sunlight had to pass through more of the earth’s atmosphere to reach him.)
He set out to figure out what it might be. First he traveled to a Swiss mountaintop, to see if the lines were diminished when viewed through a smaller portion of atmosphere. They were. Then he made his way to Lake Geneva, where he observed a large bonfire on the pier at Nyon. When viewed from close by through the spectroscope, he saw no dark bands, only the normal spectrum. But when viewed from the top of the tower in Geneva, a dozen miles across the lake, the spectrum was crossed by the same dark lines that Piazzi Smyth had observed on Tenerife and that Janssen had observed over Paris. He was by now almost certain that they were caused by water vapor that was suspended in the air above Lake Geneva. With the cooperation of a Parisian gasworks, he set about making an artificial atmosphere to confirm his guess. A span of metal tubing stood in for the breadth of the entire atmosphere. Buried in a box of sawdust and enclosed at either end with panes of glass, the tube was filled with water vapor under pressure. At one end of the tube, an array of gas jets sent a beam of strong light through the tube, while Janssen observed at the other end of the tube with his spectroscope. He saw the same dark bands he’
d seen over Paris, which had first been noticed by Brewster in 1833 and which Piazzi Smyth had seen wax and wane on top of the mountain in Tenerife in 1856. The more the pressure was raised, the darker the bands appeared. The greater the length of tubing, the darker they appeared. Janssen was now certain that the dark bands were caused by water vapor in the earth’s atmosphere. He wasted no time in concluding that the lines could also be used to search for water vapor in the atmospheres of other celestial objects. He asserted immediately, for example, that there was no water vapor present in the atmosphere of the sun, a remarkably assured statement.
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Piazzi Smyth’s own interest in spectroscopy, which had waned after his Tenerife expedition, was reignited by the news that Janssen had managed to observe the solar prominences for the first time during a total solar eclipse in India in 1868. Soon after the Indian eclipse, Piazzi Smyth bought himself a new spectroscope. It was a small wooden device just four inches long and less than an inch in diameter, with an eyepiece at one end and a diffraction slit at the other. Inside lay a series of alternating prisms, cleverly arranged so that the light that passed through them emerged from the spectroscope at the same angle at which it had entered. While not a poor man’s device (costing some two pounds), the pocket spectroscope was the province solely of neither professional meteorologists nor astronomers.
