Thus, for instance, the rising[8\3] of the Pleiades in the evening was a mark of the approach of winter. The rising of the waters of the Nile in Egypt coincided with the heliacal rising of Sirius, which star the Egyptians called Sothis. Even without any artificial measure of time or position, it was not difficult to carry observations of this kind to such a degree of accuracy as to learn from them the number of days which compose the year; and to fix the precise season from the appearance of the stars. [Note 8\3: Ideler (Chronol. i. 242) says that _this_ rising of the Pleiades took place at a time of the year which corresponds to our 11th May, and the setting to the 20th October; but this does not agree with the forty days of their being "concealed," which, from the context, must mean, I conceive, the interval between their setting and rising. Pliny, however, says, "Vergiliarum exortu æstas incipit, occasu hiems; _semestri_ spatio intra se messes vindemiasque et omnium maturitatem complexæ." (H. N. xviii. 69.) The autumn of the Greeks, ὀπώρα, was earlier than our autumn, for Homer calls Sirius ἀστὴρ ὀπωρινός, which rose at the end of July.] A knowledge concerning the stars appears to have been first cultivated with the last-mentioned view, and makes its first appearance in literature with this for its object. Thus Hesiod directs the husbandman when to reap by the rising, and when to plough by the setting of the Pleiades.[9\3] In like manner Sirius,[10\3] Arcturus,[11\3] the Hyades and Orion,[12\3] are noticed. {117} [Note 9\3: Πληίαδων Ἀτλαγενέων ἐπιτελλομενάων. Ἄρχεσθ' ἀμητοῦ· ἀρότοιο δὲ, δυσομενάων. Αἵ δή τοι νύκτας τε καὶ ἤματα τεσσεράκοντα Κεκρύφαται, αὔτις δὲ περιπλομένου ἐνιαυτοῦ Φαίνονται. _Op. et Dies_, l. 381.] [Note 10\3: Ib. l. 413.] [Note 11\3: Εὖτ' ἂν δ' ἑξήκοντα μετὰ τροπὰς ἠελίοιο Χειμέρι', ἐκτελέσῃ Ζεὺς ἤματα, δή ῥα τότ' ἀστὴρ Ἀρκτοῦρος, προλιπὼν ἱερὸν ῥόον Ὠκεανοῖο Πρῶτον παμφαίνων ἐπιτέλλεται ἀκροκνέφαιος. _Op. et Dies_, l. 562. Εὖτ' ἂν δ' Ὠρίων καὶ Σείριος ἐς μέσον ἔλθῃ Οὐρανὸν, Ἀρκτοῦρον δ' ἐσὶδῃ ῥοδοδάκτυλος ἠὼς. Ib. 607.] [Note 12\3: . . . . . . . αὐτὰρ ἐπὴν δὴ Πληϊάδες Ὑάδες τε τὸ τε σθένος Ὠρίωνος Δύνωσιν. Ib. 612. These methods were employed to a late period, because the Greek months, being lunar, did not correspond to the seasons. Tables of such motions were called παραπήγματα.--Ideler, _Hist. Untersuchungen_, p. 209.]