Inspiration to watch the eclipse on August 21
Philip Greenspun's Weblog 2017-07-13
I read American Eclipse: A Nation’s Epic Race to Catch the Shadow of the Moon and Win the Glory of the World, about the eclipse of 1878.
The book has some helpful advice for those who want to succeed in Academia:
James Craig Watson had journeyed to the Centennial from Michigan, where he served as a professor of astronomy. .. Watson’s vanity was not without foundation, however. He had risen from an impoverished childhood of factory work and apple peddling to enter the University of Michigan as a mathematical prodigy at age fifteen. Six years later, he was on the faculty, where he proved popular with students. Among the reasons, undoubtedly, was his lax grading. One year he reportedly gave passing grades on a final exam to his entire class, including a student who had died toward the beginning of the course.
Also some good history:
Eclipses do not occur randomly; they follow patterns known since ancient times. Lunar eclipses can happen only at full moon, solar eclipses at new moon, and both types can take place only within defined “eclipse seasons” that recur every six months or so, shifting slowly backward year by year. A rhythm reigns in the long run as well. Eclipses of a similar character—lunar versus solar, partial versus total—repeat themselves after the passage of precisely 6,585 and one-third days. … It was not until the eighteenth century that astronomers were able to forecast the path of a total solar eclipse with a modicum of accuracy. The best known of these early eclipse mappers was Edmond Halley, the Englishman who famously predicted the return of a comet that now bears his name.
A mid-level government bureaucrat could afford a townhouse in Northwest D.C.!
Cleveland Abbe had created something historic—the first regular weather forecasting service in the United States—but within a year the chronically cash-strapped Cincinnati Observatory was forced to abandon the venture, and Abbe too was soon dispatched, placed on unpaid leave. General Myer, just then seeking to create a weather service on a national level, called on Abbe for advice and quickly offered him a job as his chief meteorologist. At last finding stable employment, Abbe moved to Washington. Recently married, he soon fathered a son, then two more. From his respectable salary he bought a sizable townhouse on I Street, with a lunette-topped doorway in front, a garden in the rear, and, inside, plaster cornices adorning twelve-foot ceilings. It had once been home to James Monroe and, at the beginning of Monroe’s presidency, had served as the executive mansion while the White House, burned by the British in the War of 1812, underwent final repairs. Abbe’s office was a short walk away, on G Street, where the Army Signal Service (as the Signal Corps had now come to be known) occupied a three-story brick building topped by weather vanes, rain gauges, wind meters, and other “toys which excite the envy of all the neighboring boys,” as one observer put it.
(Something like that would cost 100 years of a civil servant’s salary today?)
What about the experience of the eclipse itself?
Simon Newcomb, meanwhile, was hiding in the camp’s photographic darkroom to sensitize his vision. (Other astronomers, for the same effect, bandaged their eyes.) Newcomb emerged just three minutes before totality. By now, the sun was a mere sliver. As he made his way to his telescope, he noted the “lurid” color of the landscape. “The light seemed no longer to be that of the sun, but rather to partake of the character of an artificial illumination.” With just a minute to go before totality, another bizarre phenomenon became visible to some. As if the sun were being projected through shallow water at the beach, narrow bands of light and shade rippled across the ground, or—from the viewpoint of astronomer Edward Holden, who was stationed atop the Teller House Hotel in Central City, Colorado—across the roof. “They coursed after each other very rapidly,” he wrote, “seeming about 3 feet from center to center, the dark band being, say, 6 inches wide, the interval being bright.” These wavy lines, termed shadow bands, are not always seen but can be dramatic, as at the total eclipse of 1842 in Southern France, where the undulation was reported to be so striking that “children ran after it and tried to catch it with their hands.” The cause of these ripples is the same that makes stars twinkle—currents of warm and cold air that bend light as it passes through the atmosphere. Indeed, shadow bands have been called, poetically, “visible wind.”
The sun’s crescent had now grown exceedingly slender, a mere filament. It continued to shrink, like an ember burning itself out at the ends. Before vanishing, however, this glowing thread produced a final brilliant display. It shattered into a string of shimmering jewels. These dancing points of light, called Baily’s beads (described and explained by British astronomer Francis Baily in 1836), are the last of the sun’s rays filtering through valleys on the edge of the moon. In the closing seconds before the onset of a total solar eclipse, darkness falls with disorienting rapidity. It can feel as if you are losing your eyesight, or perhaps your sanity. The dimming light does not just surround you; it swallows you. The very ground seems to give way.
And so [due to life-threatening altitude sickness that forced Cleveland Abbe down from the 14,000′ summit], the one true astronomer atop Pikes Peak spent most of totality doing what a team of amateurs was doing in Denver, sketching the corona while viewing it with the naked eye. He was not disappointed, however, to perform so little science. Langley had previously confided to Cleveland Abbe a secret wish—“ to see the eclipse (I have ‘observed’ two but not seen any as a spectator)”—and a week after the event he would write of its visceral impact: “I once experienced an earthquake, and I think this and a total eclipse of the sun are two things that it is no use trying to describe; you must feel or see for yourself.”
About one quarter of the book, by a male author, is devoted to female victimhood. Maria Mitchell had a career at the U.S. Naval Observatory and then as a professor at Vassar College. Wikipedia says that she was elected to the American Academy of Arts and Sciences in 1848 and to the American Association for the Advancement of Science in 1850. American Eclipse says that she obtained jobs ahead of male applicants, employers apparently recognizing her superior skills. Consistent with “Are women the new children?” the author describes Mitchell being celebrated for being a woman occupied with science, rather than for scientific accomplishments:
ON DENVER’S EASTERN EDGE, the Vassar party did not attempt anything technically complex during totality. The three women at telescopes—Maria Mitchell, Cora Harrison, and Elizabeth Abbot—examined the corona’s shape and color, and searched for unknown planets. The others made naked-eye observations of the landscape and sky. The women saw Mercury, Mars, and Venus. They found no Vulcan. For this group of observers, however, viewing the eclipse was arguably less important than being viewed. The Vassar women, far from the sexless Amazons that Dr. Clarke had warned would result from female higher education, presented irrefutable, concrete evidence that science and femininity could coexist. These astronomers in pleated dresses provided “an attraction to the gaping, yet respectfully distant, multitude of masculines, almost as absorbing as the eclipse,” a reporter wrote. “PROF. MITCHELL HERSELF, as with iron-gray curls fluttering under a broad-brimmed Leghorn, she swept the heavens with a four-inch telescope, or directed with native majesty and grace the operations of her assistant nymphs, was a figure, and perfectly commanding.” The Vassar astronomers also proved inspirational to members of their own sex. “[ W] omen of low and high degree throughout the territory turned during that day their thoughts toward the hill, even as the pilgrims of old prayed with their faces toward Jerusalem,” wrote another correspondent, “for from the mound where the group stood there radiated a light, that sent its rays hopefully into more than one woman’s heart—a heart with longings for study, culture, improvement, that the simple fact of her being a girl had unjustly deprived her of because old prejudices had hedged her path and defined her duties.”
FOR MARIA MITCHELL, the eclipse had produced no great scientific discoveries, but her expedition too had achieved a remarkable goal. “The success of this party is one more and pointed arrow in the quiver of woman suffrage argument and logic,” wrote a correspondent for the New York Sun. The Denver press gauged her accomplishment even more generously. “Recently, here in our midst, a conspicuous example of the power and grasp of the feminine intellect has been exhibited,” effused the Rocky Mountain News. “We allude to Miss Mitchell, and the great interest she is exciting as a scientist. . . . In this she has done a service which all the women’s rights pleaders on the continent could never dream of accomplishing.”
Yet Denver could still claim a celebrity. “Mr. Edison is doubtless the most famous inventor of this or any other age,” the Rocky Mountain News commented, “but we doubt whether he deserves more credit for his marvellous attainments in invention than does Maria Mitchell for demonstrating the capacity of women for the highest and best mental activity and scientific research.”
[Wikipedia notes that “Mitchell never married”. How is that different from modern times? See “Women in Science”: “The women I know who are university professors, by and large, are unmarried and childless. By the time they get tenure, they are on the verge of infertility.”]
This is the weakest part of the book. The author doesn’t show that Professor Mitchell could have achieved greater success if she had identified as a man. In fact, he describes that greatest American male astronomers of the day as having tremendous career difficulties, partly due to a lack of popular interest and partly due to the fact that Congress didn’t want to find science until World War II:
“It must be acknowledged that in few of the civilized nations of our time have the higher sciences made less progress than in the United States,” observed Alexis de Tocqueville, the French political thinker, after his visit to America in 1831. “Many Europeans, struck by this fact, have looked upon it as a natural and inevitable result of equality; and they have thought that, if a democratic state of society and democratic institutions were ever to prevail over the whole earth, the human mind would gradually find its beacon-lights grow dim, and men would relapse into a period of darkness.” Simon Newcomb did not subscribe to this view, but the American astronomer agreed that his own country faced a special challenge. “In other intellectual nations, science has a fostering mother,” he maintained, “in Germany the universities, in France the government, in England the scientific societies. . . . The only one it can look to here is the educated public.” In a democratic and egalitarian America, the citizenry was in charge of the nation’s destiny, and therefore advancing science in the United States required convincing the populace of the value of research—that it was worth promotion and investment.
The book touches on the “science is settled” arguments of our time. Back then astronomers had trouble figuring out why Mercury moved as it did. One hypothesis was the planet Vulcan, orbiting yet closer to the sun. This planet was actually spotted during the eclipse by Professor Watson, America’s greatest “planet hunter” (where “planet” back then included asteroids). Einstein’s General Theory of Relativity, about 40 years later, provided a different explanation for Mercury’s movements so close to the heavy sun.
The book also reminds us how little we knew of our world until only recently. Today we have helium in our kids’ balloons, but it was discovered as a spectral line coming out of the sun in 1868 and not isolated on Earth until 1895.
There is also some material on Thomas Edison, who built an instrument to measure heat (infrared light) emitted by the sun’s corona during the eclipse:
“Have you ever been in Chicago before?” one newsman asked. “Yes,” Edison replied, “thirteen years ago. I had a linen duster, $2.50, and a railroad pass. I was not interviewed then.”
Edison’s desire, often, was to perch on the engine’s prow. He lounged on the cowcatcher, on a cushion provided by the engineer, propelled forward by iron and coal and steam as he took in the scenery “without dust or anything else to obstruct the view,” as he put it.
What did the smartest scientists of the day think of Edison?
Scientists, however, were not convinced that the lamp was as magical as Fox portrayed. Would it prove cost-effective and durable enough for everyday use? How did it differ from incandescent lights being developed by competitors? Fueling the skepticism was the fact, now abundantly clear, that Edison had been stringing the public along for more than a year by telling what could generously be described as embellishments, more reasonably termed lies, about his progress on the invention. Some scientists who knew Edison well, who had been with him on the American frontier for the eclipse of 1878, came to disavow his membership in their fraternity. Britain’s Norman Lockyer, who after seeing Edison at work in Rawlins had praised the inventor as “no unwary experimenter,” now denounced his actions as exposing an “absolute incompatibility with a truly scientific spirit,” and added sharply, “Let scientific men once and for all repudiate these false and unwholesome displays of ignorance.” Henry Morton, who had perched with Edison on the Union Pacific cowcatcher and had privately expressed himself “under so many obligations to your kindness,” now became one of Edison’s severest critics. Morton called Edison’s electric light “a conspicuous failure, trumpeted as a wonderful success . . . nothing less than a fraud upon the public.”
If the scientists had no confidence in Edison’s light bulb, he had enough confidence in them to found and fund Science, still America’s leading journal in this area.