Hyperboreans and Riphaean Mountains ethnography (Arimaspi, Issedones) followed by a phonological note on common-dialect vowel change: -os endings losing e becoming ē, examples and accent/quantity discussion.
Ἑλλάνικος Ὑπερβόρειοι γράφει διὰ διφθόγγου. Πρώταρχος τὰς Ἄλπεις Ῥίπαια ὄρη οὕτω προσηγορεῖσθαι καὶ τοὺς ὑπὲρ τὰ Ἄλπεια ὄρη κατοικοῦντας πάντας Ὑπερβορέους ὠνομάσθαι. Δαμάστης δ´ ἐν τῷ περὶ ἐθνῶν, ἄνω τῶν Σκυθῶν Ἰσσηδόνας οἰκεῖν, τούτων δ´ ἀνωτέρω Ἀριμασπούς, ἄνω δ´ Ἀριμασπῶν τὰ Ῥίπαια ὄρη, ἐξ ὧν τὸν βορέαν πνεῖν, χιόνα δὲ μήποτε αὐτὰ ἐκλείπειν· ὑπὲρ δὲ τὰ ὄρη ταῦτα Ὑπερβορέους καθήκειν εἰς τὴν ἑτέραν θάλασσαν. Καλλίμαχος δὲ τοὺς αὐτούς φησι εἶναι τοῖς Ἀριμασποῖς. Τὰ εἰς 'ος' λήγοντα καθαρὰ ἁπλᾶ ὑπὲρ δύο συλλαβὰς κατὰ τὴν κοινὴν διάλεκτον τῷ 'η' παραληγόμενα οὐκ ἔστιν εὑρεῖν εἰ μὴ τὸ αἰζηός ὀξυνόμενον. καὶ τοῦτο ἐκ πάθους ἔχει τὸ 'η'. παρὰ γὰρ τὸ ἀεὶ καὶ ζέω ὁ ἀεὶ ζέων καὶ ἀκμάζων κατὰ τὴν ἡλικίαν γίνεται αἰζεός καὶ κατ´ ἐπαύξησιν τοῦ 'ε' εἰς 'η' αἰζηός. Ἀπολλώνιος μὲν ὁ τοῦ Ἀρχιβίου σὺν τῷ 'ι' οἶδεν αὐτό, λέγων γεγονέναι ἐκ τοῦ αἰζήϊος. ἀλλ´ εἰ ἦν ἀπὸ τοῦ αἰζήϊος, οὐκ ὤφειλεν ὀξύνεσθαι, ἀλλὰ προπερισπᾶσθαι. ἡ γὰρ ὀξεῖα καὶ ἡ βαρεῖα εἰς περισπωμένην συνέρχονται οἷον Ἀχελώϊος Ἀχελῷος, ὑπερώϊον ὑπερῷον. καὶ δῆλον ὅτι ὥσπερ ἀπὸ τοῦ Αἰτωλός γίνεται Αἰτώλιος κατὰ παραγωγὴν τοῦ αὐτοῦ σημαινομένου φυλαττομένου καὶ ἀπὸ τοῦ κάπρος κάπριος, οὕτω καὶ ἀπὸ τοῦ αἰζηός αἰζήϊος. πρόσκειται κατὰ τὴν κοινὴν διάλεκτον· τὸ γὰρ ἀρχῆος καὶ Ἀχηός καὶ παληός
Hellanicus writes Ὑπερβόρειοι with a diphthong. Protarchus says that the Alps are so called the Rhipaean mountains, and that all those dwelling beyond the Alpine mountains were called Hyperboreans. Damastes, in his work On Peoples, says that above the Scythians dwell the Issedones, and above these the Arimaspians; above the Arimaspians are the Rhipaean mountains, from which the north wind blows, and snow never leaves them; and that beyond these mountains the Hyperboreans extend as far as the other sea. Callimachus says that these are the same as the Arimaspians.
Among words ending in -ος, the simple pure forms of more than two syllables, in the common dialect, with η in the penult, cannot be found except αἰζηός, accented with an acute. And even this has η by way of a modification: for from ἀεί and ζέω, “one who is always living and in his prime as regards age” becomes αἰζεός, and by lengthening ε to η, αἰζηός. Apollonius the son of Archibius knows it with ι, saying that it has come from αἰζήϊος. But if it were from αἰζήϊος, it ought not to be accented with an acute, but to have the circumflex on the antepenult; for an acute and a grave combine into a circumflex, as in Ἀχελώϊος → Ἀχελῷος, ὑπερώϊον → ὑπερῷον. And it is clear that just as from Αἰτωλός there comes Αἰτώλιος by derivation, with the same meaning preserved, and from κάπρος, κάπριος, so also from αἰζηός, αἰζήϊος. The phrase “in the common dialect” is added; for ἀρχῆος and Ἀχηός and παληός…