Monosyllables, and words accented on the last syllable, when they end with a single consonant preceded by a single vowel, or by a vowel after qu, double their final consonant before an additional syllable that begins with a vowel:  as, rob, robbed, robber; fop, foppish, foppery; squat, squatter, squatting; thin, thinner, thinnest; swim, swimmer, swimming; commit, committeth, committing, committed, committer, committees; acquit, acquittal, acquittance, acquitted, acquitting, acquitteth.

EXCEPTIONS.—­1.  X final, being equivalent to ks, is never doubled:  thus, from mix, we have mixed, mixing, and mixer. 2.  When the derivative retains not the accent of the root, the final consonant is not always doubled:  as, prefer’, pref’erence, pref’erable; refer’, ref’erence, ref’erable, or refer’rible; infer’, in’ference, in’ferable, or infer’rible; transfer’, a trans’fer, trans’ferable, or transfer’rible. 3.  But letters doubled in Latin, are usually doubled in English, without regard to accent, or to any other principle:  as, Britain, Britan’nic, Britannia; appeal, appel’lant; argil, argil’laus, argilla’ceous; cavil, cav’illous, cavilla’tion; excel’, ex’cellent, ex’cellence; inflame’, inflam’mable, inflamma’tion.  See Observations 13 and 14, p. 199.

RULE IV.—­NO DOUBLING.

A final consonant, when it is not preceded by a single vowel, or when the accent is not on the last syllable, should remain single before an additional syllable:  as, toil, toiling; oil, oily; visit, visited; differ, differing; peril, perilous; viol, violist; real, realize, realist; dial, dialing, dialist; equal, equalize, equality; vitriol, vitriolic, vitriolate.

EXCEPTIONS.—­1.  The final l of words ending in el, must be doubled before an other vowel, lest the power of the e be mistaken, and a syllable be lost:  as, travel, traveller; duel, duellist; revel, revelling; gravel, gravelly; marvel, marvellous.  Yet the word parallel, having three Ells already, conforms to the rule in forming its derivatives; as, paralleling, paralleled, and unparalleled. 2.  Contrary to the preceding rule, the preterits, participles, and derivative nouns, of the few verbs ending in al, il, or ol, unaccented,—­namely, equal, rival, vial, marshal, victual, cavil, pencil, carol, gambol, and pistol,—­are usually allowed to double the l, though some dissent from the practice:  as, equalled, equalling; rivalled, rivalling; cavilled, cavilling, caviller; carolled, carolling, caroller. 3.  When ly follows l, we have two Ells of course, but in fact no doubling:  as, real, really; oral, orally; cruel, cruelly; civil, civilly; cool, coolly; wool, woolly. 4.  Compounds, though they often remove the principal accent from the point of duplication, always retain the double letter:  as, wit’snapper, kid’napper,[114] grass’hopper, duck’-legged, spur’galled, hot’spurred, broad’-brimmed, hare’-lipped, half-witted.  So, compromitted and manumitted; but benefited is different.