Rules for compositors and readers at the University Press, Oxford · Oxford University Press
DOUBLING CONSONANTS WITH SUFFIXES
Words of one syllable, ending with one consonant preceded by one vowel, double that consonant on adding -ed or -ing: e.g. drop dropped dropping fit fitted fitting stop stopped stopping Words of more than one syllable, ending with one consonant preceded by one vowel, and accented on the last syllable, double that consonant on adding -ed or -ing: e.g. allot allotted allotting commit committed committing infer inferred inferring trepan trepanned trepanning But words of this class _not_ accented on the last syllable, _do not double the last consonant_[25] on adding -ed, -ing: e.g. balloted, -ing banqueted, -ing bayoneted, -ing benefited, -ing biased, -ing billeted, -ing bishoped, -ing blanketed, -ing bonneted, -ing bracketed, -ing buffeted, -ing carpeted, -ing chirruped, -ing combated, -ing cricketing crocheted, -ing crotcheted, -ing, -y discomfited, -ing docketed, -ing faceted, -ing ferreted, -ing fidgeted, -ing, -y filleted, -ing filliped, -ing focused, -ing galloped, -ing gibbeted, -ing gossiped, -ing, -y initialed, -ing junketed, -ing marketed, -ing packeted, -ing paralleled, -ing pelleted, -ing picketed, -ing piloted, -ing profited, -ing rabbeted, -ing rabbiting rickety riveted, -ing russeted, -ing, -y scolloped, -ing tennising trinketed, -ing trousered, -ing trumpeted, -ing velvety visited, -ing wainscoted, -ing In words ending in _-l_, the final consonant is generally doubled, whether accented on the last syllable or not: e. g. annulled, -ing appalled, -ing apparelled, -ing barrelled bethralled, -ing caballed, -ing channelled, -ing compelled, -ing cudgelled, -ing dishevelled, -ing empanelled, -ing extolled, -ing forestalled, -ing grovelled, -ing impelled, -ing installed, -ing kennelled, -ing levelled, -ing libelled, -ing marshalled, -ing parcelled, -ing quarrelled, -ing revelled, -ing rivalled, -ing shovelled, -ing trammelled, -ing travelled, -ing tunnelled, -ing [25] ‘We must, however, still except the words ending in _-el_, as levelled, -er, -ing; travelled, -er, -ing; and also worshipped, -er, -ing.’—J. A. H. M.
Text from Project Gutenberg, public domain in the United States.