discussion of accentuation of -ιον and place names; examples of proparoxytone vs paroxytone forms; list of Greek place names and remarks on Homeric forms and accentuation
παροξυνόμενα ὥσπερ τὸ ἰνίον. τὸ γὰρ τειχίον ὑποκοριστικὸν καὶ τὸ κλειδίον. * Τὰ διὰ τοῦ 'ιον' τρισύλλαβα προσηγορικὰ ἔχοντα πρὸ τοῦ 'ι' δύο σύμφωνα ἢ κατὰ σύλληψιν ἢ κατὰ διάστασιν παροξύνεσθαι θέλει, ὁπότε πρὸ τοῦ 'ι' οὐκ ἔστιν ἀμετάβολον οἷον ἱστίον, κυμβίον, ἰσχίον, ἑρκίον. τὸ μέντοι ὅρκιον προπαροξυνόμενον κτητικοῦ τύπου ἔχεται· ἐπεὶ δὲ ταὐτόσημόν ἐστι τῷ ὅρκῳ, παρωνύμῳ εἴδει ὑποπεπτωκέναι φαμὲν ὡς τὸ Αἰτώλιος, κάπριος, αἰζήϊος· εἶπον ὁπότε πρὸ τοῦ 'ι' οὐκ ἔστιν ἀμετάβολον, διὰ τὸ ἴκριον καὶ ἴχνιον. Τὰ διὰ τοῦ 'ιον' τρισύλλαβα κύρια προπαροξύνονται, Ἴλιον πόλις Τρῳάδος ἀπὸ Ἴλου, ἣν οἱ Τρῶες Ἄτην ἐκάλουν καὶ Ἄτης λόφον. οὐδετέρως παρὰ πᾶσι, παρ´ Ὁμήρῳ δὲ θηλυκῶς. τὸ γὰρ «Ἴλιον αἰπύ» (Il. Ο 71) νοθεύει Ἀρίσταρχος. δευτέρα ἐν τῇ Προποντίδι παρὰ Ῥυνδάκῳ ποταμῷ. τρίτη Μακεδονίας Ἑλένου κτίσμα. τετάρτη Θεσσαλίας. πέμπτη Θρᾴκης κατὰ Βιζύην. Δέρριον. Ῥήγιον πόλις Ἑλληνίς. Ἴσθμιον. Ῥύτιον πόλις Κρήτης (Il. Β 648), ὅπερ Τυραννίων οὐκ εὖ παροξύνει ὡς πεδίον· οὔτε γὰρ ὑποκοριστικόν, οὔτε εἰ ἦν ὑποκοριστικόν, παρωξύνετο, καθότι τρίβραχυ. Θρόνιον, Σπήλιον. Ὄβριον τὸ ὄρος. Κούριον πόλις Κύπρου ἀπὸ Κουρέως τοῦ Κινύρου παιδός. Ἡρόδοτος πέμπτῃ (c. 113). ἔστι καὶ πόλις Αἰτωλίας. Χώριον ἡ πόλις, ἐπὶ γὰρ ὑποκοριστικοῦ παροξύνεται. Δαύνιον πόλις Ἰταλίας. Λυκόφρων (v. 1254) «ὑπὲρ Λακίου Δαυνίου τ´ ᾠκισμένην». Οἴνιον. Σέστιον πόλις ἐν μεσογείᾳ Οἰνωτρῶν. Αἴγιον πόλις Ἀχαΐας, ὡς Εὔδοξος ἐν ἕκτῃ. Σούνιον δῆμος Λεοντίδος φυλῆς. Ὅμηρος δὲ ἄκρον καλεῖ «ἀλλ´ ὅτε Σούνιον ἄκρον» (Od. γ 278). Δώριον πόλις Μεσσηνίας μία τῶν τριῶν, ὧν Ὅμηρος μνημονεύει «καὶ Πτελεὸν καὶ Ἕλος καὶ Δώριον» (Β 594). Πύθιον τὸ πάλαι μεσαίτατον τῆς ἐν Κρήτῃ Γόρτυνος. καὶ Μακεδονίας Πύθιον, ἐν ᾧ καὶ τὰ Πύθια ἐπιτελεῖται. ἔστι καὶ Πύθιον πλησίον τοῦ Ἀστακηνοῦ κόλπου. Ἄκτιον πόλις Ἀκαρνάνων πρώτη ἀπὸ τοῦ Ἀμβρακικοῦ κόλπου ἀρξαμένοις. ὁμωνύμως δὲ λέγεται καὶ τὸ ἱερὸν τοῦ Ἀπόλλωνος καὶ ἡ ἄκρα ἡ ποιοῦσα τὸ στόμα τοῦ κόλπου καὶ ἡ πόλις.
Accented on the penult, like ἰνίον; for τειχίον is a diminutive, and likewise κλειδίον.
Trisyllabic appellatives in -ιον that have before the ι two consonants, either in combination or separated, are required to be accented on the penult, whenever before the ι there is no “immutable” consonant, as in ἱστίον, κυμβίον, ἰσχίον, ἑρκίον. Ὅρκιον, however, being accented on the antepenult, follows the type of possessive adjectives; but since it is synonymous with ὅρκος, we say that it has fallen under the class of denominatives, like Αἰτώλιος, κάπριος, αἰζήϊος. I said “whenever before the ι there is no immutable consonant” because of ἴκριον and ἴχνιον.
Trisyllabic proper names in -ιον are accented on the antepenult: Ἴλιον, a city of the Troad, from Ἴλος, which the Trojans called Ἄτη and the hill of Ἄτη. It is neuter in all authors, but in Homer feminine; for the line «Ἴλιον αἰπύ» (Il. Ο 71) Aristarchus rejects as spurious. A second (Ἴλιον) is in the Propontis by the river Ryndacus; a third in Macedonia, a foundation of Helenus; a fourth in Thessaly; a fifth in Thrace near Bizye. Δέρριον. Ῥήγιον, a Greek city. Ἴσθμιον. Ῥύτιον, a city of Crete (Il. Β 648), which Tyrannion does not correctly accent on the penult like πεδίον; for it is neither a diminutive, nor, even if it were a diminutive, would it be accented on the penult, since it has three short syllables. Θρόνιον, Σπήλιον. Ὄβριον, the mountain. Κούριον, a city of Cyprus, from Κουρεύς, the son of Cinyras; Herodotus in the fifth book (c. 113). There is also a city of Aetolia. Χώριον, the city; for in the diminutive it is accented on the penult. Δαύνιον, a city of Italy. Lycophron (v. 1254): «ὑπὲρ Λακίου Δαυνίου τ᾽ ᾠκισμένην». Οἴνιον. Σέστιον, a city inland of the Oenotrians. Αἴγιον, a city of Achaea, as Eudoxus in the sixth book. Σούνιον, a deme of the Leontis tribe; but Homer calls it a headland: «ἀλλ᾽ ὅτε Σούνιον ἄκρον» (Od. γ 278). Δώριον, a city of Messenia, one of the three which Homer mentions: «καὶ Πτελεὸν καὶ Ἕλος καὶ Δώριον» (Β 594). Πύθιον, formerly the central district of Gortyn in Crete; and there is also a Πύθιον of Macedonia, in which the Pythian games are celebrated; and there is also a Πύθιον near the Astacene gulf. Ἄκτιον, a city of the Acarnanians, the first for those starting from the Ambracian gulf. And the sanctuary of Apollo is also called Ἄκτιον, and likewise the headland that forms the mouth of the gulf, and the city.