[93] This has been clearly shown by LAPLACE in the _Precis de l'Histoire de l'Astronomie_, which forms the fifth book of his _Exposition du Systeme du Monde_ (fifth edition). He gives a _resume_ of what he believes to have been the chief results obtained by the Chaldaean astronomers (pp. 12-14 in the separate issue of the _Precis_ 1821, 8vo). It would now, perhaps, be possible, thanks to recent discoveries, to give more precise and circumstantial details than those of Laplace. [94] AURES, _Essai sur le Systeme metrique assyrien_, p. 10 (in the _Recueil de Travaux relatifs a la Philologie et a l'Archeologie egyptiennes et assyriennes_, vol. iii. Vieweg, 4to, 1881). We refer those who are interested in these questions to this excellent paper, of which but the first part has as yet been published (1882). All previous works upon the subject are there quoted and discussed. [95] "Sixty may be divided by any divisor of ten or twelve. Of all numbers that could be chosen as an invariable denominator for fractions, it has most divisors."--FR. LENORMANT, _Manuel d'Histoire ancienne_, vol. ii. p. 177, third edition. [96] AURES, _Sur le Systeme metrique assyrien_, p. 16. A terra-cotta tablet, discovered in Lower Chaldaea among the ruins of Larsam, and believed with good reason to be very ancient, bears a list of the squares of the fractionary numbers between 1/60 2 and 60/60 2, or 1/60, calculated with perfect accuracy (LENORMANT, _Manuel_, &c. vol. ii. p. 37). See also SAYCE, _Babylonian Augury by means of Geometrical Figures_, in the _Transactions of the Society of Biblical Archaeology_, vol. iv. p. 302. [97] LENORMANT, _Manuel_, &c. vol. ii. p. 177, third edition. [98] _Ibid._ p. 37. [99] LENORMANT, _Manuel_, vol. ii. pp. 175, 178, 180. G. SMITH, _Assyrian Discoveries_ (London, 1876, 8vo), pp. 451, 452. RAWLINSON, _Ancient Monarchies_, vol. i. pp. 100, 101, fourth edition. We know that the _Astronomical Canon_ of Ptolemy begins with the accession of a king of Babylon named Nabonassar, in 747 B.C. M. Fr. LENORMANT thinks that the date in question was chosen by the Alexandrian philosopher because it coincided with the substitution, by that prince, of the solar for the lunar year. Astronomical observations would thus have become much easier to use, while those registered under the ancient system could only be employed after long and difficult calculations. A reason is thus given for Ptolemy's contentment with so comparatively modern a date. (_Essai sur les Fragments cosmogoniques de Berose_, pp. 192-197.) [100] See the paper by M. T. H. MARTIN, of Rennes, _Sur les Observations astronomiques envoyees, dit on, de Babylone en Grece par Callisthene_, Paris, 1863. [101] The texts to this effect will be found collected in the essay of M. Martin. We shall be content here with quoting a phrase from Cicero which expresses the general opinion: "Chaldaei cognitione siderum sollertiaque ingeniorum antecellunt." _De Divinatione_, i. 91.