I believe that in the fact of each mute appearing in a fourfold form (i.e. sharp, or flat, lene, or (so-called) aspirate), lies the essential character of the mutes as opposed to the liquids.
Y and w.—These sounds, respectively intermediate to γ and i (the ee in feet), and to υ and u (oo in book), form a transition from the vowels to the consonants.
[§ 204]. It has been seen that the sixteen mutes are reducible to four series. Of these series, p, t, k, s, may respectively be taken as the types. Of the liquids it may be predicated as follows:—
1. That m is allied to the series p.—The combination inp has a tendency to become imp.
2. That n is allied to the series t.—The combination imt has a tendency to become either impt, or int.
3. That l is allied to the series k.—The evidence of this lies deep in comparative philology.
4. That r is allied to the series s.—The evidence of this is of the same nature with that of the preceding assertion.
The series p and k have this peculiarity.—They are connected with the vowels through w and u (oo), and through y and i (ee) respectively.
[§ 205]. The French word roi and the English words oil,
house, are specimens of a fresh class of articulations; viz., of compound vowel sounds or diphthongs. The diphthong oi is the vowel o modified, plus the semivowel y (not the vowel i) modified. The diphthongal sound in roi is the vowel o modified, plus the semivowel w (not the vowel u or oo) modified. In roi the semivowel element precedes, in oil it follows. In roi it is the semivowel allied to series p; in oil it is the semivowel allied to series k. The nature of the modification that the component parts of a diphthong undergo has yet to be determined; although it is certain there is one. If it were not so, the articulations would be double, not compound.