2459. A vowel which stands before two consonants, or a double consonant,
belonging to the same word, so that its natural quantity cannot be
determined from the scansion of the word, is said to possess _Hidden
Quantity_.
2460. The natural quantity of such a vowel may sometimes be ascertained:
(_a._) from the statements of ancient writers; (_b._) from the way in
which the vowel is written in Latin inscriptions (see 24, 29); (_c._)
from the transliteration of the word into other languages, especially
Greek; (_d._) from the etymology of the word, or from a comparison of it
with kindred words in other Indo-European languages; (_e._) from
comparison with derived words in the Romance languages. But all these
kinds of evidence must be used with great caution.
2461. For the length of a vowel before #ns#, #nf#, and certain other
groups of consonants, see 122.
2462. In inceptive verbs (834) the ending #-scō# is thought to be always
preceded by a long vowel: as, #crēscō#, #nāscor#, #proficīscor#.
2463. In the perfect indicative active, perfect participle passive and
kindred formations of verbs in #-gō# preceded by a short vowel, as
#agō#, #regō#, the theme syllable shows a long vowel: as, #lēxī#,
#rēxī#, #tēxī#; #āctus#, #lēctus#; #rēctor#; #āctitō#.
(B.) SOME PECULIARITIES OF QUANTITY IN OLD LATIN.
2464. For the preservation of a long vowel in certain specific endings
in old Latin, see 132.
2465. Final #-āl# is sometimes preserved long in the nominative
singular: as, #bacchānāl# (Plaut.); also the syllable #-es# in the
nominative singular of stems in #-t-# which have the genitive in #-itis#
(477): as #mīlēs# (Plaut.) 171, 1.
2466. #Hic#, #illic# and #istic#, when adverbs, have a long final
syllable; but when nominative singular masculine, have the final
syllable regularly short.
2467. In Plautus #frūstrā# always where determinable (seven times) has
the final syllable short. #contrā# sometimes has a short final syllable
in old Latin.
2468. In Latin poetry down to the time of Cicero, final #s# often does
not “make position” before a following consonant (66); as, #tempŭs fert#
(Plaut.); #magĭs stetisse# (Ter.).
2469. The first syllable of #ille#, #illic# (the pronoun), #quippe#,
#immō#, #inde#, #unde#, #nempe#, #omnis#, and perhaps #iste#, is
sometimes shortened.
In #ille#, #illic#, #quippe#, and #immō# the shortening is, some hold,
due to the fact that in common speech one of the double consonants was
often pronounced faintly or not at all; while in #inde#, #unde#,
#nempe#, and #omnis# the nasal was very faintly sounded before the
following consonant. But some authorities hold that always in #nempe#,
and sometimes in #ille#, #quippe#, #inde#, #unde#, and perhaps #iste#,
before an initial consonant final #e# disappears, and the word becomes a
monosyllable.