The wild West might seem to be an unlikely place for the Navy, but on 29 July 1878, astronomers working for the U. S. Naval Observatory occupied the Rocky Mountains and the Wyoming and Colorado prairies in force. They were not alone. On that summer afternoon, scientists from some of the nation’s most prestigious observatories and universities and thousands of other people from Canada to Louisiana gazed in awe upon one of nature’s rarest phenomena—a total eclipse of the sun.
A solar eclipse offered the scientists their only opportunity to study the sun’s external features unhindered by its brilliant surface glare. With the solar disk totally obscured by the moon, they might be able to answer many longstanding questions about the sun’s composition. Did the mysterious halo known as the corona shine because of reflected light or was it incandescent? Astronomers also hoped the momentary darkness accompanying totality would enable them to sweep the sky for Vulcan, a small planet many believed revolved around the sun within the orbit of Mercury. Recent advances in optics, spectroscopy, and dry plate photography made it possible to record and analyze this eclipse as none had ever been.
Preparations for what was to be a scant three-minute event began months before. Much of the activity centered in Washington, D.C., at the U. S. Naval Observatory, one of the nation’s leading astronomical institutions. The observatory planned to send several teams to stations along the eclipse’s path. Since the end of the Civil War, the observatory had vigorously pursued celestial phenomena wherever they occurred. In 1869, a government team journeyed to Siberia to observe a solar eclipse. A year later, four Navy astronomers covered another eclipse from Gibraltar and Sicily. In 1874, in its most ambitious undertaking, the observatory dispatched eight specially trained teams to Siberia, China, the Indian Ocean, and the South Pacific to record the transit of Venus across the sun.
Still basking in the glow of having discovered Mars’s two satellites the previous year, the Naval Observatory commenced preparations for the great eclipse. They began in early spring 1878, and that was none too soon. The superintendent. Rear Admiral John Rodgers, recognized that successful coverage would require the cooperation of the nation’s best astronomers. His own staff could not do it alone. He obtained a special congressional appropriation of $8,000 and invited selected astronomers to become members of the observatory teams heading west. The government agreed to pay transportation to and from the stations and expenses totaling $5 per day.
Rodgers encouraged international participation. Eight British scientists expressed a strong desire to join the expeditions. Admiral Rodgers sent certificates of identification to the British consul-general in New York, accrediting the visitors and exempting them from paying customs duties on their equipment.
In response to special instructions for viewing the eclipse published in spring 1878 issues of scientific journals by the observatory’s staff, letters from the trained and untrained offering assistance inundated Rodgers’s office. Although his limited budget forced him to turn away all amateurs and many professionals as official participants, Rodgers did encourage their cooperation by requesting drawings of the eclipse as they perceived it.
Preparations became more frenzied as spring moved into summer. Insufficient time and money for the construction of special equipment demanded that observatory personnel modify existing telescopes. Workmen stripped mountings and clock drives from their telescopes and married them to cameras. Joseph A. Rogers, a one-time observatory employee and frequent adviser, donated dry photographic plates he had made. They were a welcome improvement over the older wet plates that required onsite preparation and processing within a few minutes of exposure. The Rogers plates could be exposed, stored, and processed once the teams returned to Washington.
The observatory’s major task was to dispatch five teams to stations along the path of the eclipse’s totality—Creston and Separation in Wyoming; and Central City, La Junta, and Las Animas in Colorado. An auxiliary team of nonobservatory scientists would view the eclipse from Pike’s Peak.
Arranging for the transport of men and fragile instruments became the unenviable task of astronomer Edward Holden. After considerable negotiation, he rented a mail car from the Pennsylvania Railroad.
On 2 July, telescopes, transits, cameras, photographic plates, baggage, and other items left Washington and stopped over in Pittsburgh to load other astronomers’ equipment. Despite Holden’s care and concern, the precious cargo suffered rough handling. The teams would require at least a week at their stations to set up and make necessary repairs.
As Pennsylvania Railroad Postal Car Number 10 rolled into Creston, Wyoming on 14 July, assistant astronomer Aaron N. Skinner was filled with anything but awe at his first view of the “wild West.” He wrote his impressions of the dry, hot plains in a letter to Superintendent Rodgers dated 14 July 1878:
“The Postal Car stands on a side track opposite the station. Creston Station is in the midst of an immense elevated plain covered with clumps of low sage brush and grease wood. It is only from the south east to the north that mountains may be seen to the distance. . . The only inhabitants here are Station Master who is a telegraph operator, his wife, and a few Chinamen . ..It is as still as death here. If I had nothing to do, I should find it unendurable.”
William Harkness, head of the Creston team, arrived a week later with Lieutenant E. W. Sturdy from the U. S. Naval Academy; noted lens and telescope maker, Alvan G. Clark; Professor Otis H. Robinson of Rochester University; and astronomer-artist Leopold Trouvelot and his son George. Harkness echoed Skinner’s observations: “In such a place how could life be otherwise than dull?
Assisted by the commanding officer of nearby Fort Steele, Harkness, Skinner, and their colleagues established camp. The postal car served as an office and a dormitory. Skinner had already constructed the temporary observatory of rough boards “ 12 by 22 feet, 7 feet high at the eaves, and 10 feet high at the ridge pole ... the eastern side of its roof was of boards, while the western side was of canvas, so arranged as to be readily removed when the instruments were in use (from “Reports on the Total Solar Eclipses of July 29, 1878, and January 11, 1880” p. 30). By 25 July, the Creston team was ready for the great eclipse.
At Separation, a point midway between Creston and the town of Rawlins, Simon Newcomb of the Nautical Almanac Office set up his station on a small plain depressed below the general ground level and protected from the wind on the south and west by a natural sand parapet. About 360 miles southeast of Separation on the Colorado plains, Asaph Hall’s men busily readied their station Hall, the dean of the observatory’s astronomers, had already achieved worldwide fame for his discovery of Mars’s moons. By 23 July, they had set up the temporary observatory. All that remained was to construct foundation piers for the instruments and repair and adjust balky equipment. Nineteen miles east of them on the Arkansas River was West Las Animas, headquarters of John Eastman and his team.
The astronomers assigned to Central City drew the choicest assignment. The booming gold mining town, about 30 miles west of Denver, sat on the cool eastern slope of the aspen-covered Snowy Range at an elevation of 8,400 feet. When the observatory’s Edward Holden and his colleagues arrived there on 25 July, they had a readymade observatory awaiting them—the flat roof of the 150- room, three-story Teller House. Known as the most elegant establishment west of the Mississippi and east of San Francisco, the hotel’s substantial chimneys served as excellent piers for the telescopes and other instruments. Four days remained to set up the equipment and enjoy Central City’s hospitality and fine opera house before the main event.
For all five of these teams, ordeal, weather, and illness had not entered into the almost faultless picture. Not so with another group associated with the Naval Observatory under the leadership of Professor Samuel P. Langley, director of the Allegheny Observatory. Langley, future Secretary of the Smithsonian Institution and a pioneer in the quest for manned flight, chose Pike’s Peak for his eclipse station. He was joined by his brother John, professor of chemistry at the University of Michigan; Cleveland Abbe of the Signal Service; and several other volunteers. They first had to conquer the summit of Pike’s Peak, no small task when encumbered by a five-inch Clark telescope packed in five boxes weighing nearly half a ton.
The baggage had to be hauled 18 miles from the railroad station at Colorado Springs to the summit over a narrow, winding footpath. Only the lighter bundles could be strapped to the backs of donkeys. In fact, the tortuous path was so bad that the men abandoned much of the equipment on the way up.
“The ‘Peak,’ which I reached on the 20th,” wrote Langley in a report of the event, “is a comparative plain, of some acres in extent, formed of sharp-pointed and fractured boulders of granite of every size, from that of a paving stone to many tons, making the mounting of instruments or even the pitching of tents, at first sight, seem hardly possible.”
The situation grew worse. The stone Signal Service station at the summit leaked and rain poured freely upon the instrument boxes. Langley coated the steel portion of his telescope with lard and covered the remainder with canvas. The 14,110-foot altitude left the men panting with the slightest exertion. They set up tents for sleeping, but cold, wet clouds permeated the flimsy shelters and dampened their clothes. The sun disappeared, and hail pelted them as they toiled to set up the instruments. All suffered from altitude sickness. Abbe’s condition worsened, and he finally had to be evacuated from the mountain after a snowstorm blanketed the camp. The precipitation even worked its way into the tents, where Langley found a snowdrift beside him when he awoke. Fortunately, as eclipse day approached, conditions improved and the men recovered their health.
Even though every afternoon of the previous week had been cloudy, Monday, 29 July, dawned clear at all five eclipse stations. From his vantage atop Pike’s Peak, Samuel Langley noted in his report that this day was “a complete contrast to its predecessors, the sky being almost cloudless and of a deep and transparent blue never seen near the Atlantic Coast.”
The eclipse would last two hours and 18 minutes. At Denver, totality occurred at 1529 and lasted less than three minutes. The Naval Observatory astronomers, as well as scientists at other locations peppering the mountains west of Denver, scurried to make last-minute preparations. Banks and many Denver businesses closed early as residents gathered near the Capitol and others jockeyed for position on rooftops.
The astronomers at all five observatory stations concentrated on observing the sun’s corona and searching for Vulcan. They gathered data in traditional ways (hastily scribbling notes and sketches) and with the newest technology (exposing dry plate negatives).
At Las Animas, John Eastman examined the coronal structure using a spectroscope coupled to a five-inch equatorial telescope. In Creston, Wyoming, William Harkness searched the coronal spectrum for telltale clues of its chemical composition. At each station, observers searched in vain for Vulcan.
In contrast to their arrival, little fanfare accompanied the astronomers’ return east with baggage, telescopes, and mountains of data. The scientists spent many months analyzing the information and writing reports. They made several immediate observations, however. The corona seemed less brilliant than in several previous eclipses and also seemed to be shaped differently. The rays projecting from the sun’s north and south poles resembled luminous hairs or the fuzzy lines of force surrounding a magnetized sphere. The coronal rays projecting from the solar equator were enormous. This peculiar phenomenon puzzled the 19th-century astronomers. How could the solar atmosphere, subject to the laws of gravity, extend millions of miles beyond the sun’s surface? A series of photos taken at Rawlins, Wyoming, by Dr. Henry Draper, past photographic consultant for the Naval Observatory, demonstrated a continuous spectrum, proving the corona is non- incandescent and therefore reflects solar light.
The astronomers also seemed to have resolved one other question beyond a reasonable doubt. Except for several unconfirmed sightings, there was no evidence of a planet Vulcan. Until the discovery of Pluto in 1930, the solar system was thought to contain only eight major planets.
The solar eclipse expeditions of 1878 were over, and the fame of those who participated seemed as fleeting as the passage of the lunar disk across the sun. Yet that was not important. The U. S. Naval Observatory gave many scientists the opportunity to participate in one of the most ambitious studies of a celestial phenomenon ever attempted.
