Glides are only transitional sounds. They are intermediate to Consonants and Vowels, combining the characteristics of certain central-aperture consonants with the wide or expanded quality of vowels, but differing from vowels in not having a fixed configuration. ...in representing glides the peculiarities of consonants and vowels are blended: the accented fingers, by being straightened, contribute a consonant characteristic; while the second phalanx of the thumb, by being held at an angle to the plane of the palm, imparts to the glide positions the wide, without giving them the firm, quality of vowel positions.
Breath-Glide - A transitional aspiration, of organic quality corresponding to that of the adjoining elements [a soft effect of the Consonants, back primary; top primary; Point primary; Lip primary; etc.]. Although this glide has no fixed abiding place, and is of a somewhat variable organic formation, in its effect it is very closely allied to the Throat consonant aspirate, and is therefore represented with a posterior position of the palm and a separation of the index and center fingers, which are characteristic features of Throat positions. This is the only Non-Vocal glide, and hence is the only one in the representation of which the voice phalanx is unaccented.