U.
U is long in ūse, confūsion; or short, as ŭs, concŭssion.
It coalesces with a, e, i, o; but has rather in these combinations the force of the w consonant, as quaff, quest, quit, quite, languish; sometimes in ui the i loses its sound, as in juice. It is sometimes mute before a, e, i, y, as guard, guest, guise, buy.
U is followed by e in virtue, but the e has no sound.
Ue is sometimes mute at the end of a word, in imitation of the French, as prorogue, synagogue, plague, vague, harangue.
Y.
Y is a vowel, which, as Quintilian observes of one of the Roman letters, we might want without inconvenience, but that we have it. It supplies the place of i at the end of words, as thy, before an i, as dying; and is commonly retained in derivative words where it was part of a diphthong, in the primitive; as, destroy, destroyer; betray, betrayed, betrayer; pray, prayer; say, sayer; day, days.
Y being the Saxon vowel y, which was commonly used where i is now put, occurs very frequently in all old books.
GENERAL RULES.
A vowel in the beginning or middle syllable, before two consonants, is commonly short, as ŏppŏrtunity.
In monosyllables a single vowel before a single consonant is short; as stag, frog.