How Newton dated the Argonauts
Jed Z. Buchwald and Mordechai Feingold
NEWTON AND THE ORIGIN OF CIVILIZATION
544pp. Princeton University Press. £34.95 (US $49.50).
978 0 691 15478 7
V isitors to Westminster Abbey who pause in front of the tomb of Sir Isaac Newton may find parts of its iconography hard to decipher. Their predecessors were similarly puzzled. The Gentleman’s Magazine on April 22, 1731, sought to inform its readers about what they might expect to see. It described the relief on the sarcophagus which shows putti engaged in experiments with a prism, a reflecting telescope, a balance and a furnace. These activities call to mind Newton’s work on the theory of light and colours, the invention that first brought him to the attention of the Royal Society, the gravitational theory of the Principia (published by that Society in 1687), and the public service which Newton performed as Warden and later Master of the Mint from 1696. The figure of Newton himself is recumbent on top of the sarcophagus, resting its right arm on four books. Two of these, the Principia and the Opticks (1704), came out in several editions during their author’s lifetime. Another, The Chronology of Ancient Kingdoms Amended, published posthumously in 1728, blew up a storm of criticism on both sides of the Channel when it circulated in abbreviated form shortly before his death. Facing Newton come two winged cherubs, holding a scroll, which carries a depiction of the solar system and the terms of a converging series (Newton’s method for calculating the roots of functions). Rising behind Newton is a pyramid, at the top of which rests the weeping figure of Urania, muse of astronomy. Beneath her is a celestial globe, “on which”, as the Magazine explains, “several of the Constellations are drawn, in order to shew the path of the Comet in 1681, whose period he has with the greatest sagacity determin’d: And also the Position of the solstitial Colure mention’d by Hipparchus by which (in his Chronology) he has fixed the time of the Argonautic expedition”.
Most of us have learned to associate Newton’s name with the mathematics of the calculus, the experimental scientific method, and the theory of gravitation. Knowledge of Newton’s chronology is less widespread. One product of the technical discipline of chronology, as it was practised in the seventeenth century, has lodged itself in the contemporary mind: the suggestion by James Ussher, Archbishop of Armagh, that the world was created “upon the entrance of the night preceding the twenty third day of October” 4004 BC. In truth, Ussher’s date was one of many ventured by scholars during his lifetime. They drew on a tradition of Christian chronology – much of it focused on determining the correct cycle for the date of Easter – which in England dated back as far as the writings of Bede in the early eighth century. Ussher’s method is relatively easy to understand and perhaps to ridicule, if rather harder to put into practice. It involved an enumeration of the passage of time calculated through the account of the generations of Adam and his descendants given in the Hebrew Bible. Yet Ussher also participated in a scientific revolution in chronology, which gathered pace as calendrical disputes were given spice by confessional divisions brought about by the Reformation.
Newton’s interest in scientific chronology was initially sparked by the international discussion about setting the date of Easter and about the adoption of the Gregorian reform of the calendar. This was the subject of correspondence between Newton’s great rival, Gottfried Wilhelm Leibniz, and the Royal Society in the early months of 1700. Many of Newton’s contemporaries, notably John Graunt and Sir William Petty, were interested in using statistics to estimate the historical speed of population growth in a manner that might confirm the framework of biblical time. Happy to accept elements of the received chronology of the Hebrew Bible, Newton desired to regulate information provided by ancient dynasty lists, which appeared to describe a succession of generations. Rather than consider whether there had been enough time to people the earth, he tried to calculate how much time, on average, would be needed for the orderly succession of a given number of named rulers. He was less careful than some of his contemporaries in his analysis of textual evidence. The extreme antiquity of the Egyptian dynasties presented a problem, which Newton solved by adopting the identification made by Sir John Marsham in the early 1670s between the historical king Sesostris and the biblical pharaoh Sesac. For proof of the radical shortening of secular history that this move implied, and to make it conform with the chronology of the ancient Greeks that he proposed, Newton eventually looked to astronomy. He hoped to use the periodicity provided by the precession of the equinoxes to date historical observations of the heavens, reported in the fourth century BC by Eudoxus, in order to control the earliest dates in Greek history. These he associated with the expedition of the Argonauts (which he believed to be historical fact), the Trojan War, and the writings of Hesiod. In reworking data that he took from the Hellenistic Commentary of Hipparchus, Newton sought to identify historical “colures”. A colure is the meridian that passes through the poles of the celestial sphere and cuts the sun’s apparent path through the heavens at the points that it has reached at the solstices (or, alternatively, at the equinoxes). The region of the heavens identified by such a colure shifted over time due to the precession of the equinoxes and thus its description could in theory generate precise dates.
The calculation of colures was the method that Newton used to present one of the most astonishing claims of his Chronology, which was to date the expedition of the Argonauts to 937 BC and to conclude that this was just before the birth of Priam, future king of Troy. Newton’s need for precision about the location of particular stars in order to determine colures was one cause of his harrying the Astronomer Royal, John Flamsteed, for the completion of his celestial atlas. Newton’s preliminary findings intrigued Caroline, Princess of Wales, and interested numerous visitors to London in the decade or so before he died. Through one of those visitors, Leibniz’s friend the Abbé Conti, Newton’s ideas were broadcast more widely, especially in the Parisian Académie des Inscriptions et Belles Lettres. There they were first published, and first attacked in public, generating notoriety and suspicion that directly affected their subsequent reception in England and elsewhere. Newton died before he could fully rebut the criticisms that his work received and before he could see it properly into print. The celebration of the Chronology on his tomb was therefore something of a gesture of defiance during a controversy about both secular and biblical history that was, in 1731, still in full swing.
It is exactly fifty years since the American historian, Frank Manuel (1910–2003), first set out the key elements of this story from the evidence of Newton’s working papers. Now two new scholars, Jed Buchwald and Mordechai Feingold, have returned triumphantly from doing battle on the same field. Feingold once edited a Festschrift for Manuel, but there are important differences between the approach that he and his collaborator have taken and that of the earlier pioneer. Buchwald’s exposition of Newton’s historical astronomy is unparalleled in detail and clarity and will appeal to astronomers as much as historians. It makes superb use of modern techniques of illustration both to show what Newton was up to and how he used the celestial atlases and measurements available to him. Buchwald’s long survey of Newton’s attitude to measurement and precision in experiment begins the development of the most important and original argument that he and Feingold present. They claim that what is distinctive in Newton’s style of reasoning is his use of approximation and repeated averaging to overcome uncertainties in the data provided by the senses through the practice of mathematics. The coherence with which this theme is advanced is remarkable. It embraces some of Newton’s earliest astronomical observations, his controversial engagements over the behaviour of light and the discovery of his method of working with regnal years and historical generations. Most impressively, it provides a theoretical basis for considering the otherwise bewildering compromises made in Newton’s astronomical and historical search for the colures. This argument for intellectual unity in Newton’s method of working gives Newton and the Origin of Civilization philosophical as well as historical originality and importance.
As his relations with Flamsteed and a host of others indicated, Newton did not personally provide much of a model for scientific collaboration. The collaboration of Buchwald and Feingold is similarly not without problems for a reader. Their two styles are noticeably different, both in writing and footnoting. In expertise, they complement one another, even if in execution they sometimes clash. The reader is drawn in by Feingold’s accounts of the history of chronology and the growth of Newton’s original interest in mythology and the ancient past. Key features of that development are nevertheless obscured. The most important of these is the extent to which, before 1700, Newton’s earliest pursuit of the history of civilization went hand in hand with an argument about the history of cosmology that was intended to support the methodological choices that he had made in writing the Principia. By contrast, Buchwald challenges the reader to enjoy the complexity of Newton’s later reasoning in scientific chronology as much as he evidently does. This is hard work (alleviated by some of the book’s appendices), but it brings rewards and allows a much deeper understanding of the Chronology than that presented by Manuel. Yet the juggling act is not perfect. From time to time, Buchwald starts a historical hare that Feingold was evidently supposed to chase, but which runs off across the reader’s mind leaving both of them behind.
One might try to bring a couple to ground. Both writers make use of dates for Newton’s manuscript writings that remain unsure. Neither really tries to explore or explain the problems involved. Occasional mention is made of the presence or absence of a particular title from Newton’s library, but comparatively little time is spent on identifying which works of chronology Newton used and how he did so. This is a pity, since this is an area where we now know more than Manuel did, in particular through the discovery of Newton’s copy of Marsham’s work at the Linda Hall Library in Kansas City. Buchwald and Feingold print a photograph of some of Newton’s markings in that book, without any explanation. One of the most important things that Newton took from Marsham was the identification of Sesostris with Sesac. This argumentative move had parallels elsewhere in Newton’s work. For example, in Newton’s theological writing (which Feingold plausibly argues had little to do with his chronology), there is a constant theme of seeking identity (“synchronisms”) between earlier and later recensions of the same prophecies, thus reducing two apparently diverse stories to one. Newton’s long-standing interest in understanding prophecy involved finding historical truth behind a symbolic language. The way in which he worked often required comparison and weighted approximation, even if it was not as specifically mathematical as his method in chronology. Newton’s technique here might also be compared to his persistent use of chronological information derived from the assumption that mythological figures had real historical antecedents. Buchwald and Feingold suggest that Newton’s professional investigation of counterfeiting at the Mint in the late 1690s encouraged him to doubt the validity of historical testimony and turn decisively to the evidence of astronomical data. Yet Newton was already sceptical about the historical witnesses to Christian doctrine by the beginning of the decade.
Newton and the Origin of Civilization may not always be an easy book, but it represents a climacteric in our understanding of its subject’s life and thought. The fever of speculation has cooled, and for the first time modern observers can properly remark on the consistency of thought and the mathematical power of argument that lie beneath Newton’s controversial Chronology. As a consequence, we can start to appreciate why it might be considered as much a monument to Newton’s genius as any of his other works.
Scott Mandelbrote is a Fellow of Peterhouse, Cambridge, and an Editorial Director of the Newton Project.
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