Department of History
University of California, Irvine
 Instructor:    Dr. Barbara J. Becker

Week 6.  The Golden Age of Positional Astronomy.

excerpt from
"Astronomers Royal"
by Barbara J. Becker
[a version of this article originally appeared in History of Astronomy:  An Encyclopedia (1997), John Lankford (ed.)

As England vied with other European states for hegemony on the seas in the seventeenth century, the accurate computation of a ship's position, particularly its longitude relative to the meridian of a land-based observatory or port of departure became a national priority.  Of principal concern was the preservation of English naval superiority, with the attendant goals of reducing risk to colonial expeditions, mapping unexplored waters, and retrieving sunken treasures which were all important to growing mercantile interests.

The Paris Observatory

But just as pressing was the need to establish a working observatory on English soil to match or better that already in operation in France, particularly after reports reached England in 1674 that a Frenchman claimed to have solved the longitude problem by astronomical means.
John Flamsteed (1646-1719)

The French method met with informed criticism from the young English astronomer, John Flamsteed, who argued that current ephemerides and star catalogues were not sufficiently accurate to support it.  Charles II promptly named Flamsteed his "Astronomical Observator," and agreed to build an observatory at Greenwich to remedy the situation.  Thus England's first government-supported scientific post was established to serve a practical political, economic, and social need, not to investigate contemporary philosophical or cosmological questions.

Defining the boundaries of appropriate research at Greenwich over the years has been a matter of continual negotiation, with each Astronomer Royal molding the Observatory's program to suit his own personality, interests, and abilities.  This succession of eccentric personalities in a dynasty of mathematical astronomers served as interlocutors between science and society in Britain.  Although duty-bound by Royal Warrant to the seemingly narrow task of taming the celestial clockwork for the greater good and utility of the Nation, the role of England's Astronomer Royal evolved in response to altered social perceptions of how astronomy could best serve that goal.  Moreover, changes in the sense of what it meant to do astronomy, how one did it, and even why, raised questions about individual choice and personal opportunity versus public responsibility and accountability.

Greenwich Observatory

When Flamsteed assumed the post of Astronomer Royal in 1676, the English Crown was unaccustomed to purchasing scientific expertise and information.  Consequently, there were no ready answers to questions about how much such information should cost, what "product" was reasonable to expect in exchange for financial support, or how long it might take to complete the job.  Although the King funded the construction of the observatory building and granted Flamsteed an annual salary of £100, he provided no money for the purchase of observing instruments or the employment of assistants, an arrangement that caused considerable difficulty concerning the ownership of the data collected at Greenwich throughout the Observatory's first century of operation.
Flamsteed's sextant.
Flamsteed obtained some instruments through patrons' gifts, and he constructed many others himself at his own expense.  His self-sufficiency, coupled with the lack of a formal mechanism or tradition to guide the communication of data collected at Greenwich to those interested in them for purposes other than the improvement of celestial navigation, bolstered Flamsteed's belief that these data were his own to communicate as he chose, a belief that placed him at odds with his fellow astronomers.

To gain administrative control over the work of the Observatory and to forestall any future problems of the type Flamsteed had posed to the Crown and his scientific colleagues, Queen Anne established the Board of Visitors in 1710, the first of such measures taken by the Government in the Observatory's history.  The Board, consisting of Royal Society officers and other Council members, were charged with ensuring that Observatory instruments were in working order, replacing them as necessary, and receiving annually a fair and true report from the Astronomer Royal of observations made.  For Flamsteed, this action provided further evidence that those he served neither appreciated nor understood him as a professional in his own right.
Edmond Halley (1656-1742)

Constituting the Board of Visitors did not resolve the problem of who owned the Astronomer Royal's recorded observations.  Both Edmond Halley and especially Halley's successor, James Bradley, treated the data they amassed during their tenures as personal property, jealously guarding against their public disclosure while alive and ultimately bequeathing them to family members, actions seen by other English astronomers as not only obstructing the continuity of work at Greenwich, but limiting their own opportunities to match or better the strides being made by their Continental colleagues.
James Bradley (1693-1762)
It was the case of Bradley, whose notes required extraordinary efforts over several decades to recover, that ostensibly prompted the Royal Society's Council in 1764 to draft a set of detailed regulations codifying the Astronomer Royal's rights and responsibilities.  But the regulations also reflected a deeper concern.  Because the longitude problem resisted solution in spite of nearly a century of effort by four successive Astronomers Royal and the added incentive of a generous prize established by the Government in 1714, there was a growing recognition in the scientific community of the institutional permanence of the office in contrast to the transiency of the individuals occupying it, and the consequent need to protect the post from further abuse by personal whim.
Nevil Maskelyne (1732-1811)

The 1764 regulations were largely welcomed by Nevil Maskelyne, the fifth Astronomer Royal and the first to serve under them.  His response, when coupled with the stability afforded by his near half-century as the Observatory's director, smoothed the institution's transition to a more mature and routine phase of its operation.  In terms of administrative matters, Maskelyne worked within the confines of the new regulations to build a positive relationship between the Observatory and the Board of Visitors as well as its fiscal agent, the Board of Ordnance.  But there were two developments in the early years of Maskelyne's tenure resulting from projects undertaken by individuals working independently of Greenwich that permanently altered the institution's scientific purpose and research agenda:  the claim by John Harrison to have built a marine chronometer of sufficient accuracy to solve the longitude problem, and the discovery of a new planet by William Herschel.

William Herschel (1738-1822)
The suggestion that the longitude problem had been solved by mechanical means raised serious questions about the future direction of astronomical observation at Greenwich.  After all, astronomers had long assumed that it would yield only to greater precision in recording the changing positions of planetary bodies against the background of fixed stars, an effort Maskelyne was well-equipped to lead.  His personal and professional bias in favor of astronomical methods for finding longitude at sea was unperturbed by the consistently excellent performance of Harrison's chronometer in the protracted series of trials ordered by the Board of Longitude, embroiling Maskelyne in disputes with Harrison and other clockmakers throughout his tenure.  Indeed, his fervor led him to intensify his efforts to provide mariners with tables of lunar positions so accurate they would rival the new timepieces in their ability to keep ships on course.  To that end, Maskelyne expended considerable effort determining the precise coordinates of three dozen referent stars, and instituted the preparation and publication of an annual ephemeris for navigators, the Nautical Almanac, a task which became so labor-intensive that it eventually required the employment of additional staff.  As navigators' reliance on chronometers increased, the Admiralty, which assumed administrative control over Greenwich in 1818, assigned the Astronomer Royal the responsibility for rating those instruments bound for naval service.  Thus, the Astronomer Royal's timekeeping duties were extended rather than attenuated by the encroachment of accurate and seaworthy timepieces on traditional Greenwich turf.

Herschel's observatory notes of his discovery of "a curious rather nebulous star or perhaps a comet," an object which he soon realized was a planetary body (Uranus).  

The second development, William Herschel's discovery of the planet Uranus in 1781, won him the notice of King George III and the title of Royal Astronomer.  Like the Astronomer Royal, Herschel was provided with an observatory and a salary from the King, but unlike his counterpart, Herschel served the Crown as a natural historian of the heavens.  Herschel's telescope was less an instrument of measurement than a novel cabinet of curiosities through which he made the species of marvelous objects that populated the night sky accessible to the royal family on demand.  The catalogues of nebulae he produced were widely viewed as justifying his extravagant claims concerning the capabilities of his large telescopes.

Though Herschel's discoveries increased popular interest in descriptive astronomy and fuelled cosmological speculation both at home and abroad, they exemplified for Maskelyne all that astronomical research at Greenwich was not.  His commitment to serve as Britain's chief timekeeper and master astrometer insulated the Astronomer Royal from other currents in astronomy throughout much of the nineteenth century.  Questions regarding the construction of the heavens, origin of the solar system, evolution of stars, or physical make-up of celestial bodies, which captivated the growing numbers of amateur astronomers in Britain, were deemed too theoretical to be worthy of either the Government's expense or the Astronomer Royal's time.  Maskelyne's literal interpretation of the original charge to the Astronomer Royal informed his decision to restrict observations at Greenwich to those that would contribute to the continued improvement of navigation, an adaptive, albeit limiting, choice that incorporated recent improvements in timekeeping technology, suggested methods for analyzing and rectifying sources of observational error, and established a well-defined and highly specialized research niche for the Royal Observatory for the next hundred years.

A similar brand of conservatism governed the acquisition of instruments and the application of new research methodologies by the nineteenth century Astronomers Royal.  Maskelyne and his successors, John Pond and George Biddell Airy, actively developed those that enhanced precision or minimized personal differences among observers' recorded measurements, incorporating them into the staff repertoire, while leaving those that supported the pursuit of riskier, discovery-oriented projects to the growing network of enterprising individuals in the private sector.  Telescopes with apertures comparable in size to William Herschel's, for example, had no place in the Astronomer Royal's toolkit until the twentieth century.  Likewise, the application of photography and spectroscopy was resisted at Greenwich until faced with competition for Government financial support in the last quarter of the century.

John Pond (1767-1836)
John Pond, who took up Maskelyne's mantle in 1811, tried to steer the clear and steady course set by his predecessor, but he encountered challenges calling for greater administrative and programmatic flexibility than he could muster.  It was during Pond's tenure that Greenwich's reign as the principal seat of British astronomical research came to an end.  Growing numbers of astronomers, many of them amateurs with wide ranging research interests, resources, and expertise, sought leadership as well as social and intellectual support in conducting, recording, and communicating their observations, leadership the Astronomer Royal was unable to provide.  The year 1820 saw the founding of two new institutions aimed at both contributing to the Astronomer Royal's program of meridian astronomy, and extending Herschel's grand survey of the heavens:  the Astronomical Society of London (later the Royal Astronomical Society, or RAS), which supported positional and descriptive astronomers alike; and the Royal Observatory at the Cape of Good Hope, which, with its own government-appointed director, was charged with mapping the southern skies.

At the same time, Pond oversaw an expansion of Greenwich's workforce that required a division of labor and organizational plan more common to a factory or accounting office than to an observatory.  Although he was a talented observer, Pond's success in fulfilling his obligations as Astronomer Royal to the Admiralty's satisfaction was thwarted by the slovenliness of his chief assistant, his own poor health, and the inadequacy of his administrative skills.  He thus became the first Astronomer Royal to retire from office and the only one to have done so involuntarily.  Pond's successor, George Biddell Airy, the young director of Cambridge University's observatory, was selected for the post not so much for his observing skills, but rather because of his demonstrated abilities as an efficient administrator.
George Biddell Airy (1801-1892)

Airy's management style became legendary in his own time, his lengthy tenure marked by anecdotes forged of fearful reverence and bereft of needless nuance to illustrate a full range of moral lessons on doing science responsibly in an age of progress and increasing specialization.  A century's distance from so commanding a figure as Airy reduces some of the interpretive obstacles historians have faced in the past, permitting the placement of his incremental, often situation-bound, administrative decisions within the broader social, political, and economic context which informed them.  Old questions about Airy's obsession with positional astronomy as a help or a hindrance to the growth of astronomy in Britain can be more profitably rephrased in terms of institutional survival strategies and the art of designing a productive rather than a deadend research niche.

Wedded by duty and personal preference to a program of precise, efficient, and uniform measurement, Airy streamlined the collection, reduction, and dissemination of observational data by breaking down complex tasks into repetitive, specialized steps requiring little training to complete successfully.  To assist in managing the Observatory's workload (and to forestall the discipline problems Pond had encountered with his non-professional First Assistant), Airy created the post of Chief Assistant, for which he recruited qualified candidates from Cambridge University.  And he developed self-registering instruments to mechanize observations and reduce disparities resulting from individual sensory differences.  These systemic changes in the practice of astronomy at Greenwich made it possible for Airy to delegate what he defined as the tedium of "mere" observation and computation to lower-level staff in order to devote his own time to tasks more demanding of his specialized training.

Like his predecessors, Airy was one of the Government's only paid professional scientists when he began his forty-six-year regime in 1835.  But unlike them, he had no other source of income.  This practical matter combined with the Government's growing thirst for expert scientific opinion and Airy's own indefatigable sense of duty turned the post of Astronomer Royal into an all-purpose science advisory position.  Although other practicing scientists would fill the ranks of civil service in Britain before the end of his term, Airy steadfastly asserted the Astronomer Royal's pre-eminence as chief science consultant to the Crown, making himself available whenever needed on a wide variety of scientific and technical issues from structural integrity of bridges in high winds to science education reform.

By mid-century, Airy's passion for organization, so necessary to keeping the Royal Observatory with its expanded staff of observers and computers in the forefront of positional astronomy, was no longer, by itself, sufficient to keep Greenwich's program apace those being pursued elsewhere.  Although mapping the heavens was the backbone of research programs at observatories in Paris, Berlin, and St. Petersburg, it did not constrain them in the way that Airy's strict routine gripped the staff at Greenwich.  Continental astronomers applied positional methods and instruments to projects in which Airy saw little purpose.  Viewed solely in this light, his programmatic rigidity could be interpreted as less of a virtue than an institutional liability.

Indeed, several key astronomical discoveries were made by astronomers working outside the boundaries Airy deemed appropriate for research in his national observatory.  Giuseppe Piazzi of Palermo, for example, discovered a small planetary body in 1801, the first of a retinue of such objects to be found orbiting the sun between Mars and Jupiter.  (It was not until 1847 that an English astronomer, John Hind, working from a private London observatory, was able to count himself among the contributors to the growing list of planetoids.)  In 1838, Friedrich Wilhelm Bessel of the Königsburg Observatory announced what he believed to be evidence of the first successful observation of stellar parallax based on close examination of small periodic shifts in the relative positions of a select group of stars, a project Airy would not have approved at Greenwich.

Perhaps the most memorable and disquieting astronomical discovery made on Airy's watch was the sighting of a new outer planet that theorists had hypothesized as the cause of perturbations noted in Uranus' orbital path.  Likely locations for this suspected body were determined independently by two celestial mechanicians -- Urbain Jean Joseph Le Verrier in France and John Couch Adams in England.  A planet, later named Neptune, was indeed found (1846) both by Johann Gottfried Galle of the Berlin Observatory using Le Verrier's published predictions of its position, and by James Challis of the Cambridge University Observatory who had been pressed into service by Airy to conduct a search using information obtained privately from Adams.  But when sole credit for the discovery was initially awarded to Le Verrier, the Astronomer Royal was exposed to public criticism for what was perceived by many as an opportunity lost.

The sustained controversy which erupted over the assignment of priority in the aftermath of Neptune's discovery has attracted considerable attention from scientists and historians alike over the years.  Most past analyses of the Neptune episode and Airy's role in it have been based principally on published accounts of events and the mutable memory of retrospectives, however, and do not reveal fully the contemporaneous social, political, and personal considerations that informed both Airy's actions in the matter and the public face he later put on them.  The discovery of Neptune aside, Airy's unpublished papers open opportunities for historians to explore his own sense of the Astronomer Royal's responsibility to the present and future success of the whole of British astronomy.

In the last decade of Airy's tenure, a group of vocal British amateurs attracted by the investigative richness of the research agenda opened up by astronomical physics questioned the adequacy of Greenwich to contribute to progress in the new astronomy.  The Astronomer Royal's authority had been diluted in these individuals' eyes by the success of the RAS and the British Association for the Advancement of Science (BAAS), which supported the pursuit of more diverse astronomical research agendas.  Research in astronomical spectroscopy, celestial photography, and particularly solar physics had been left largely in the hands of private individuals in Britain, a decentralized arrangement which these amateurs believed jeopardized the programmatic continuity essential to the development of astrophysical theory.  In their view, ephemeral phenomena like sunspots, solar prominences, novae, and variable stars demanded routine, coordinated observations, and a network of British national astrophysical laboratories located throughout the Empire.  They publicly argued the necessity of Government support for astronomical physics to preserve Britain's leadership among world astronomers.  Airy was seasoned enough in the game of institutional survival to know that financial support the Government might provide for research of any kind at other facilities in Britain would only siphon off needed resources from his own limited allotment.  For this and other reasons, he actively opposed government support for the proposed astrophysical laboratories.

Airy was not averse to the methods and research interests of the new astronomy.  In the first decade of his tenure, growing international acceptance of meteorology, solar physics, and especially terrestrial magnetism as legitimate astronomical concerns had fanned his interest in the collection and analysis of such data for public benefit.  Although never a practitioner himself, he was an early advocate of astronomical photography, and he authorized his staff to conduct one of England's first spectroscopic studies of stars.  Nevertheless, Airy felt keenly his official responsibility to the British public whose taxes paid his salary.  In his opinion, individuals with private means were free to pursue projects of their own design, in their own way, and on their own schedule.  Indeed, the rapid development of astronomical physics exemplified the benefits to be gained by keeping such discovery-oriented scientific activity in the private sector.  Still, Airy could no longer ignore the call to diversify the research program at Greenwich, particularly after the value of celestial photography and spectroscopy as mensurational tools was demonstrated.  More importantly, he recognized the need for the Astronomer Royal to project a new style of leadership in astronomical research both at home and abroad if the post was to retain its stature in an increasingly competitive scientific market.

William Henry Mahoney Christie
Firm assurances from Airy that Greenwich staff had already begun to include astrophysical observations in their daily routine combined with the support of key figures in the RAS and the Royal Society delayed, but did not prevent, the Government's establishment of an astrophysical observatory separate from Greenwich shortly before Airy's retirement in 1881.

When the aging John Couch Adams declined the invitation to become the eighth Astronomer Royal, the post was offered to Airy's young Chief Assistant, William Henry Mahoney Christie, the first Greenwich insider to be promoted to the post.  Sharing neither Airy's disdain for observation nor his discomfort with the methods of the new astronomy, Christie had led Greenwich's spectroscopic study of stellar radial velocities.  And, though he benefitted from his predecessor's example and good counsel during the first decade of his term -- a luxury no other new Astronomer Royal had enjoyed -- Christie interpreted the responsibilities of the position in his own way and pursued research questions suited to his own interests.  He did not neglect his duties as a positional astronomer, but his familiarity with the equipment and procedures required to direct a research program more in keeping with modern trends helped the Royal Observatory begin to move, albeit slowly, toward an agenda that included astrophysics and photography.


Astronomers Royal from Flamsteed to Christie

Dates served
John Flamsteed
Edmond Halley
James Bradley
Nathaniel Bliss
Nevil Maskelyne
John Pond
George Biddell Airy
William Henry Mahoney Christie
Go to:
  • "The Construction of the Heavens" (1784-1791), by William Herschel (1738-1822)
  • "Great Astronomical Discoveries Lately Made by Sir John Herschel" (1835), Richard Adams Locke, New York Sun
  • The Unparalleled Adventure of One Hans Phaal (1850), by Edgar Allan Poe (1809-1849)
Weekly Readings
Lecture Notes