Thomas Davidson,
Chambers's Twentieth Century Dictionary 1908…
(1908)
“ Vowel, vow′el, n. a sound or tone produced by the unimpeded passage of the breath, when modified by the glottis into voice, through the tube of the mouth, which is made to assume different shapes by altering the form and position of the tongue and the lips—the letters a, e, i, o, u are called vowels, as being able to be sounded by themselves, with a continuous passage of the breath ”
