When Computers Were Human (9 page)

Of the two organizations, the Nautical Almanac Office was the first to undergo a serious reform and adopt factory methods. Its workers were more familiar with the demands of production, as they had labored under fixed deadlines since the founding of the almanac in 1767. The pressure to reform the almanac came not from the almanac staff or even from the Admiralty but from the Royal Astronomical Society, the group that had started its life in a London tavern as the simple Astronomical Society. “The most prominent subject of public interest,” reported the society president, “was the proposing of an amended form of the Nautical Almanac.”
⁵
He argued that the almanac devoted too many pages to the lunar distance method of navigation and not enough to tables that would assist contemporary navigators and astronomers. The society claimed, with no contradiction from the British Admiralty, that most ship officers had abandoned Maskelyne's technique for calculating the time. In its place, chronometers, the high-precision clocks, could “be found in perhaps every ship which relies upon astronomical means for her guidance.”
⁶

With the consent of the Admiralty, the Royal Astronomical Society formed a review board for the almanac. This committee met in the offices of the society and consisted of a broad selection of almanac users, including naval officers and astronomers, shipowners and insurance men, financiers and merchants, scientists and clergy, the Astronomer Royal and Charles Babbage.
⁷
The committee published its recommendations in 1830 and 1831. In spite of their objections to the lunar distance method, they refused to cut any of Maskelyne's lunar distance tables and suggested that such tables be expanded and redesigned. They also requested several substantial changes: new tables of the planets, values that would improve astronomical observations made on board ships, the “mean time of high water at London Bridge,” dates of Islamic holidays (“which may be occasionally useful to officers cruising in the neighbourhood of Mohammedan states”), and the expansion of many other tables. The proposed new additions increased the size of the periodical by 50 percent, but the committee felt that the calculations could be distributed
“amongst the several computers as will afford them constant employment.” “With due economy,” they concluded, “the whole of the additional computations may, in a short time, be obtained without much (if any) additional cost to the nation.”
⁸

After receiving the report of the Royal Astronomical Society, the British Admiralty appointed one of the review board members, Lieutenant William Samuel Stratford (1791–1853), to oversee the almanac and implement the needed changes. From the start, Stratford concluded that the computers would be most efficient and be most constantly employed if they worked in a central office. He gave the old staff “due notice that their services would no longer be required after the completion of the Almanac for 1833,” leased rooms for an almanac office in central London, and hired new computers. Only a few of the old staff moved to London and joined the new office. Most of the old computers wished to remain with their homes and families in the country. Stratford's staff would be drawn from city dwellers and would calculate in the almanac computing room, follow a daily schedule, and be under the watchful eye of the superintendent.
⁹

Stratford opened the new almanac office shortly before the 1835 return of Halley's comet. There was less anxiety over this return than over its 1758 appearance. No one, at least none of the major astronomers, questioned the basic principles of Newton's theory, no one argued that the comet was anything more than a celestial object, and no one decried the “spirit of calculation.” Stratford identified five major attempts to compute the comet's orbit and reviewed all five in the first volume of the almanac that was prepared under his superintendence. He reported that all of them identified roughly the same orbit and that the “principal variation appears to be in the time of the perihelion passage.”
¹⁰
He felt that the most complete calculation was done by the French astronomer Philippe Gustave Le Doulcet, Comte de Pontécoulant (1795–1874). Pontécoulant had spent five years computing the comet's path and adjusting his figures. He started with an idealized orbit, a perfect ellipse around the Sun. Step by step he added the major influences on the comet: the gravity of Jupiter, Saturn, and Uranus. He even adjusted his equation to account for the position of the Earth during the 1758 passage. His first calculations identified November 7 as the date of the perihelion. His second effort moved the date to November 13. The third retreated it to November 10. The last advanced the perihelion to the evening of November 12.
¹¹

Under the direction of Stratford, the almanac computers produced an adjustable ephemeris for Halley's comet. In comparison with Pontécoulant's calculation, it was a mundane activity, a practical contribution to astronomy rather than a grand test of Newton's theory. Once the comet had been spotted, this ephemeris could be used to plot the comet's
position in the night sky and to predict the date of perihelion. Stratford used the ephemeris to engage about one hundred astronomers, both professionals and amateurs, to search the sky for the comet and to record its position. He instructed the observers to send their records of the comet to the almanac office. From the data, the almanac computers revised their equations for the comet and filed their results for the next generation of astronomers to use. The Royal Astronomical Society praised this work as a “most useful and arduous task.”
¹²
Taken as a whole, the computations for the 1835 return halved the error of the 1758 calculation. The actual date of the perihelion, November 16, fell within sixteen days of all the major predictions. One of Pontécoulant's predictions came within three days and a few hours of the true perihelion.
¹³

7. Halley's comet in 1835 (fifth from right) with other nineteenth-century comets

The reform of the Greenwich Observatory began just as the comet swung past the sun and began retreating from view. In the eyes of contemporary astronomers, the observatory required many changes. It needed new equipment, a stronger staff, and revised methods of operation. Like the Nautical Almanac Office, it had become a center of production, but this production was considered a burden on the staff. The British Admiralty had given the observatory the responsibility of caring for the navy's stock of chronometers. Observatory personnel cleaned, tested, and corrected the time of every chronometer before it departed England on an ocean voyage. These tasks occupied an entire room of the observatory and the labor of several observatory personnel. The director of the observatory at Cambridge, George Airy (1801–1892), looked at the activities of the Greenwich staff and complained that chronometer work degraded the Royal Observatory “into a mere bureau of clerks” and added that “it is difficult even for the director to resist the contagion” of such tasks.
¹⁴

Airy had made his reputation as a reformer. Under his direction, the Cambridge Observatory had been transformed from a small, uninteresting teaching facility into “one of the pace-setting scientific centers of England.”
¹⁵
This transformation was the crowning achievement of his career at Cambridge. He had enrolled at the university as a sizar, a scholarship student too poor to pay the tuition, and he had graduated at the top of his class. He held the title of “Senior Wrangler,” a title bestowed on the student with the top score on the Tripos exam, the honors exam for students in astronomy, physics, and mathematics. For a time, Airy had also served as the Lucasian Professor of Mathematics, the position that had once been occupied by Isaac Newton and, more recently, by Charles Babbage.
¹⁶

In 1835, the Admiralty appointed George Airy as the Astronomer Royal. The first test of his leadership was a collection of unprocessed astronomical data that had been accumulated over twenty-five years. These numbers lay unused in observatory logs, some written with neat and refined digits, some scribbled in haste, some recorded with hands that had grown stiff and cramped from the cold night air. This backlog of data was “a lump of ore,” Airy observed, which is “without value till it has been smelted.”
¹⁷
The smelting process is called “reduction.” When computers reduce data, they take the raw values from the telescopes and convert them into a form that astronomers can use for research. For each observation of a celestial object, an astronomer generally records four numbers: the height of the object above the horizon (altitude), the direction of the object in the sky (azimuth), the time of day, and the date of the year. These four values change as the Earth rotates. The process of reduction collapses, or reduces, these four values into a pair of fixed numbers that represent the position of the object on the celestial sphere.

The celestial sphere is an imaginary hollow globe that surrounds the Earth. Astronomers identify positions on the celestial sphere with astronomical longitude (called the right ascension) and astronomical latitude (declination). The right ascension is measured from the celestial equator, which lies above the Earth's equator. The declination is measured from the celestial prime meridian, which runs north and south through the constellation Aries, the first constellation of spring, the traditional herald of the new year. The computations for data reduction require about ten steps, depending on how precise one wishes to be, and require a firm knowledge of trigonometry.
¹⁸

To process the Greenwich backlog, George Airy created a computing group at the observatory that resembled the staff at Stratford's almanac office. Airy's computers were mere boys, some as young as fifteen, who arrived at eight in the morning. They worked at tall desks in the original observing room of the building. This room, called the Octagon Room,
more closely resembled an eighteenth-century ballroom than the dome of a modern observatory. Edmund Halley had gazed through the room's tall, slender windows to map the night sky. Those same windows admitted the sunlight to illumine the desks and papers of the computing boys. At noon, the boys took a break for supper, and they resumed their places at one. In winter months, they would bring candles to compensate for the failing light as they computed through the afternoon. Only when the clock had passed through a complete cycle and reached the hour of eight in the evening would they be allowed to go home.
¹⁹

8. Original Greenwich Observatory with the Octagon Room

The boys were not the hairdressers of de Prony's Bureau de Cadastre, as they came to the observatory with abilities that could be compared to those of the almanac computers of Nevil Maskelyne. They generally possessed the basic skills of mathematics, including “Arithmetic, the use of Logarithms, and Elementary Algebra.”
²⁰
Some had been educated at the Greenwich Hospital School, a school that trained boys to be seamen in the navy. Many had learned their computing skill from fathers or uncles. Among Airy's early computers were two sons of an almanac computer. The boys had learned enough mathematics to expect a career in ocean trade or as civil servants or possibly as scholars at Cambridge. They became computers only because their father had died and left the family with no fortune or income.
²¹

The elder of the two boys, Edwin Dunkin (1821–1898), was seventeen when he began computing. He reported that he learned the observatory's
computing procedures from a book of printed forms that had been designed by Airy. On his first day in the Octagon Room, the chief computer placed the book in front of him and indicated the work that needed to be done. “I felt a little nervous at first,” he reported, “and a momentary fear crossed my mind that some time would be required to enable me to comprehend this intricate form, and to fill up the various spaces correctly from the Tables.” After a little instruction from the chief computer, “I began to make my first entries with a slow and tremulous hand, doubting whether what I was doing was correct or not. But after a little quiet study of the example given in the Tables, all this nervousness soon vanished.” His brother, who was two years younger, worked on simpler problems, but at the end of the day, both felt that they had mastered a small part of astronomical mathematics. “We went home tired enough to our lodgings,” Dunkin recalled, “but with light hearts and the happy thought that we had earned our first day's stipends.”
²²