814 Spring books supplement Nature Vol. 278 26 April 1979 Aurelius a San Daniele and David a ,the posi,tions of Sun and Moon on the San Cajetano at the royal court monas Wheelwrights basis of Meton's (about 430 BC) tery at Vienna during the second half approximation, in which 19 solar years of the eighteenth century; above all, correspond with 254 sidereal revolu perhaps, the 'World Machine' finished of the tions of the moon, or 235 lunations. by Ph. M. Hahn in 1791. Schwilgue As many later geared models, it made made the astronomical clock in Stras heavens use of differential gearing. bourg in 1842, more or less in this Fourteen centuries passed before tradition. His workshop was the germ A. W. Sleeswyk anything nearly as elaborate was made. of the firm of Ungerer, makers of a The interim is filled by the Arabs with most elaborate clock for the cathedral Geared to the Stars: The Evolution of their geared astrolobes, and the of Messina in 1933. Planetariums, Orreries and Astro Chinese with the waterwheel clock The line to be drawn between astro nomical Clocks. By H. C. King, in made by Cha,ng Ssu-hsiin exactly a nomical clocks and other astronomical collaboration with J. R. Milburn. Pp. 442. millennium ago. Later, this clock was displays is, of course, vanishingly thin. (Adam Hilger: Bristol, 1978.) £25. perfected by Su Sung, and lost as a In France a development occurred of link in the development of technology clock-driven armillary spheres, of IN twenty-one chapters and over 366 when the Chinese capital K'aifeng fell which Antide Janvier finished an out pages, illustrated with 333 diagrams, to the Chin Tartars in 1126. standing example in 1801. In England, reproductions of engravings and photo The first mechanical clocks date orreries were ma~nly developed as aids graphs, sprinkled with 2,236 .footnotes, from the end of the thir.teenth century, in adult education by instructors such this book gives an account of planet and the equal hour system gained uni as James Ferguson (1710-76), who, as ariums, tellurians, orre·ries, globe versal acceptance only a century la,ter. "Wheelwright of the Heavens" has a clocks, astrolabes, lunariums, astro Not surprisingly, the first clocks about chapter devoted to his Hfe and work. nomical clocks, equatoriums, satel whioh we possess detailed information, This development on the home-front litians, cometariums; all of them, to the those of the fourteenth century of of astronomy gave rise to transparent modern eye mechanical analogue com Richard of Wallingford and Giovanni demonstrational ·orreries for large puters of the Solar System, but differing de' Dondi, were astronomical clocks. audiences, and, therefore, of maximum in the way the data are displayed. These The positions of the Sun, the Moon size-a devdopment which ultimately models-often of great beauty-are and the five planets were displayed on Jed to the projection planetarium. now, as are all analogue computers, separate dials in the latter clock, which This work germJnated a quarter of being superseded. At the end of the is adequately discussed. Regrettably, a century ago as a modest project to book the most modern planetarium is the same cannot be said for the discus compile a list of extant models of the described, with the heavenly bodies sion of Richard of Wallingford's Solar System. In 1970 its scope rep.resented by spots of light projected clock, reconstituted by J . D. North and expanded so as to include astronomical on the interior of a dome vaulting over published in final form in 1976: it is clocks and biographical notes. The the audience, and controlled by a digi unnecessarily brief and marred by result bears traces of this gestation. It tal mini-computer. errors of detail. Astronomical clocks is a somewhat uneven, but readable Astronomers, who often earned their have been with us ever since those account of the elements of the early keep as astrologers, have observed from early examples were made. history of astronomy, horology and the earliest times onward the recurrent Astronomical modelmaking received instrument making for the interested motions of the heavens, and the bodies some powerful impulses from develop amateur, to whom the geometry of the moving in them--Sun, Moon and ments in cosmography. In 1543 various models is explained especiaHy planets. Whether or not awed by "the Copernicus published his De Revo well. On the other hand, the historian infinity of those spaces", they deter lutionibus, replacing Ptolemy's geo of science will find this book useful mined with ever-increasing accuracy centric Universe by the much more too, because it has retained its original the different periods of these motions, orderly heliocentric one. In 1609 character of a catalogue; none other whose ratios are never exactly expres appeared Kepler's Astronomia Nova on exists. He will recognise some obvious sible as fini,te quotients. Hence the the properties of the eUiptical planetary shortcomings-rather heavy reliance on challenge to clever craftsmen to pro orbits, providing a new basis for the secondary literature, occasional inac duce close approximations by ingenious "equation of time", that is, the curacies and the absence of a firm gearing. difference between sundial time and terminus to the references. As stated The material is arranged in a roughly mean solar time, indicated in many ibefore, the findings of J. D. North chronological order, starting with .the astronomical clocks. In the course of also referred to as J. and J. G. North little we know about Hipparchos and ,time the production of t·hese display on the clock designed and executed by Archimedes in connection with astro clocks diverged increasingly from Richard· of Walling.ford-also referred nomical models-the protohistory of scientific clockmaking, which aimed at to as Robert-are rather inaccurately the subject. Under-water archaeology greater accuracy, culminating in reproduced. The book by Leopold of brought to l,ight the next item, the Harrison's marine chronometer of 1735. 1974 on the Reinhold astronomical astonishing Antikythera mechanism, The trail of astronomical clock table clock is not among the references, probably made by a Rhodian crafts making brings us back to the late six nor is Maurice's authoritative book on man in 87 BC, lost in a shipwreck north teenth century, to the court of the German geared clocks, although an west of Crete in about 80 BC, and landgrave William IV of Hessen-Cassel, article by the same author in the salvaged by sponge-fishers in the year who employed some masters of the September issue of the Connoisseur o.f I 900. Its 30-odd gears were conserved craf,t, Eberhard Baldewein and Jost the same year (1976) is included. in lumps of calcareous accretion, Biirgi; then to England in the seven These, however, are only minor flaws which only in recent years became teenth and eighteenth centuries, when in this wide-ranging book, which offers amenable to analysis, by X-rays and Tompion, Mudge and Pinchbeck made much at a reasonable price. D gamma-rays, on which D. J. Price in clocks catering to the tastes of educated gentlemen 1974 could base the defini.tJive interpre of the time. Astronomical A . W. Sleeswyk is Professor of Applied tation. The mechanism computed the clocks of heroic complexity were made Physics at the University of Groningen, synodic month and the lunar year and in Central Europe: for instance, by The Netherlands.
C Macmillan Journals Ltd 1979