1860, I.J.G. Scheller [aut.] and George Walker [tr.], A Copious Latin Grammar (1825), in: Leonhard Tafel and Rudolph L. Tafel, Latin Pronunciation and the Latin Alphabet (Philadelphia: I. Kohler, № 202 North Fourth Street; New York: B. Westermann & Co., 440 Broadway), “The English Method”, page 142
a) In dissyllables the accent is always laid upon the penultime. b) In polysyllables the penultime is accented if the syllable be long, but in all other cases the accent is laid upon the antepenultime.
1871, Alexander John Ellis, On Early English Pronunciation, part III: Illustrations of the Pronunciation of the XIVth and XVIth Centuries (London: Asher & Co., London & Berlin; Trübner & Co., 8 and 60, Paternoster Row), chapter VIII: “Illustrations of the Pronunciation of English during the Sixteenth Century”, § 8: ‘On the Pronunciation of Shakspere’, « Gill on Accent and Metre », page 932, footnote 3
The term antepenultime here determines the dissyllabic character of the termination -tion = (-sion) in Gill’s mind.
In antepenultime the non-neutral vowels /a/, /i/, /u/ alternate with the neutral shorter /ə/, and the neutral vowel in antepenultime and penultime alternates with zero: […]
Mandibles with 4 teeth decreasing in size from the apical teeth, the antepenultime (subbasal) smallest.
2008, Ukrainian Academy of Arts and Sciences in the United States, Annals (Ukrainian-American Publishing Co.), volume 21, issues 49–50, page 104
In surnames from words extended with diminutive suffixes -ko, -ka, -ok, -ec’, -ce, where the stress is always on the antepenultime, e.g. Chárčenko (< Charkó, dim. of Charytin, ‘Chariton’, gen. sing. Charká), Démčenko (< Demkó, dim. of Demján ‘Damianus’, gen. sing Demká), Hrínčenko (< Hryn’kó, dim. of Hrýhir ‘Gregory’, gen. sing. Hryn’ká), etc.