X
X begins no English word: it has the sound of ks, as axle, extraneous.
Y.
Y, when it follows a consonant, is a vowel; when it precedes either a vowel or a diphthong, is a consonant, as ye, young. It is thought by some to be in all cases a vowel. But it may be observed of y as of w, that it follows a vowel without any hiatus, as rosy youth.
The chief argument by which w and y appear to be always vowels is, that the sounds which they are supposed to have as consonants, cannot be uttered after a vowel, like that of all other consonants; thus we say tu, ut; do, odd; but in wed, dew; the two sounds of w have no resemblance to each other.