[4] A general account of these important archaeological objects will be published by J. Needham, Science and civilisation in China, Cambridge, 1959(?), vol. 4. The original publications (in Chinese) are as follows: Wang Chen-to, "Investigations and reproduction in model form of the south-pointing carriage and hodometer," National Peiping Academy Historical Journal, 1937, vol. 3, p. 1. Liu Hsien-chou, "Chinese inventions in horological engineering," Ch'ing-Hua University Engineering Journal, 1956, vol. 4, p. 1.
[5] For illustrations of intermeshing worms in Indian cotton mills, see Matschoss, op. cit. (footnote [3]), figs. 5, 6, 7, p. 7.
[6] It is interesting to note that the Chinese hodometer was contemporary with that of Hero and Vitruvius and very similar in design. There is no evidence whatsoever upon which to decide whether there may have been a specific transmission of this invention or even a "stimulus diffusion."
[7] A summary of the content of the manuscript sources, illustrated by the original drawings, has been published by H. Alan Lloyd, Giovanni de Dondi's horological masterpiece, 1364, without date or imprint (?Lausanne, 1955), 23 pp. It should be remarked that de Dondi declines to describe the workings of his crown and foliot escapement (though it is well illustrated) saying that this is of the "common" variety and if the reader does not understand such simple things he need not hope to comprehend the complexities of this mighty clock. But this may be bravado to quite a large degree.
[8] See, for example, the chronological tables of the 14th century and the later mentions of clocks in E. Zinner, Aus der Frühzeit der Räderuhr, Munich, 1954, p. 29 ff. Unfortunately this very complete treatment tends to confuse the factual and legendary sources prior to the clock of de Dondi; it also accepts the very doubtful evidence of the "escapement" drawn by Villard of Honnecourt (see p. [107]). An excellent and fully illustrated account of monumental astronomical clocks throughout the world is given by Alfred Ungerer, Les horloges astronomiques, Strasbourg, 1931, 514 pp. Available accounts of the development of the planetarium since the middle ages are very brief and especially weak on the early history: Helmut Werner, From the Aratus globe to the Zeiss planetarium, Stuttgart, 1957; C. A. Crommelin, "Planetaria, a historical survey," Antiquarian Horology, 1955, vol. 1, pp. 70-75.
[9] Derek J. Price, "Clockwork before the clock," Horological Journal, 1955, vol. 97, p. 810, and 1956, vol. 98, p. 31.
[10] For the use of this material I am indebted to my co-authors. I must also acknowledge thanks to the Cambridge University Press, which in the near future will be publishing our monograph, "Heavenly Clockwork." Some of the findings of this paper are included in shorter form as background material for that monograph. A brief account of the discovery of this material has been published by J. Needham, Wang Ling, and Derek J. Price, "Chinese astronomical clockwork," Nature, 1956, vol. 177, pp. 600-602.
[11] For these translations from classical authors I am indebted to Professor Loren MacKinney and Miss Harriet Lattin, who had collected them for a history, now abandoned, of planetariums. I am grateful for the opportunity of giving them here the mention they deserve.
[12] A. G. Drachmann, "The plane astrolabe and the anaphoric clock," Centaurus, 1954, vol. 3, pp. 183-189.
[13] A fuller description of the anaphoric clock and cognate water-clocks is given by A. G. Drachmann, "Ktesibios, Philon and Heron," Acta Historica Scientiarum Naturalium et Medicinalium, Copenhagen, 1948, vol. 4.