O (aw) is the fullest of the Vowel-Sounds. It is made with the mouth still farther open than when we say A (ah), and somewhat farther back; or, rather, with the cavity enlarged in all directions, and especially deepened. The mouth is stretched in all ways to its utmost capacity, giving a hollow, vacant effect to the voice, instead of the rich, mellow and substantial sound of the A (ah). The Sound so produced is, nevertheless, on the one hand, a broader quality of the A (ah), and there is a strong tendency on the part of the A (ah) to degenerate into it, as when the uneducated German, says Yaw for Ja (yah). On the other hand, this sound has something of the quality of O. It is, therefore, intermediate in quality between A (ah) and O. In respect to meaning, it is the Type, Analogue, Equivalent, or Representative of Volume or Space, whether filled or unfilled by Substance. That is to say, it is the Analogue of Space, not in the sense in which we formerly regarded Space as the negation of Matter; but in the sense of Infinite Dimensionality, or of Dimensionality in all directions, as a vague generalization from the three special dimensions Length, Breadth, and Thickness. It is, therefore, round or ball-like, and huge, and, in respect to the nature of the tone, vague and vacant.
Space as mere nothing has no Letter-Sign in the Alphabet; but is represented by the blank types or spaces used by the printer to separate his syllables and words, as shown heretofore. Space as a Department of Reality, as one of the Realities of the Universe, a bastard or semi-Reality it is true, but nevertheless, belonging to that Domain, is denoted by the Vowel-Sound o (aw).
The Sound u (uh, u in curd), the fifth of the Scale, is called among Phoneticians, the Natural Vowel. It is the simple, unmodulated or unformed vocal breath permitted to flow forth from the throat or larynx with no effort to produce any specific sound. It is the mere grunt, a little prolonged; the unwrought material out of which the other and more perfect Vowel Sounds are made by modulation, or, in other words, by the shapings and strains put upon the machinery of utterance. The Hebrew scheva, the French eu, and e mute, are varieties of this easily-flowing, unmodulated, unstable, unsatisfactory sound. Like the o (aw), this sound u (uh) has a vacant, unfinished, and inorganic character as a sound, while yet, from its great fluency, its frequent occurrence tends, more than that of any other sound, to give to Language that conversational fluency, rapidity and ease which are especially characteristic of the French Tongue. From this same easy laxity of its nature all the other Vowel Sounds tend, in English particularly, when they are not accented, to fall back into this Natural Vowel; as in the following instances: Roman, broken, mirth, martyr, Boston, curd, etc.; words which we pronounce nearly Romun, brokun, murth, martur, Bostun, curd, etc.
This Sound, as to inherent meaning, is, by its alliance with the idea of flux, flow and continuity, the Type, Analogue, Equivalent or Representative in the Domain of Oral Sound of that Fundamental Conception which, in respect to Idea, we denominate Time; and of Stream-like or Currental Being of all kinds.
Space, denoted by o (aw), has relation to the Air as an atmosphere, and to the Ocean of Ether in filling the Great Spheral Dome of Empyrean or Firmament. The Vowel-Sound u (uh) has a similar relation to Fluidity or Liquidity, and, hence, to Water as a typical fluid, to the Ocean Flux or Tide, to the Flowing Stream, etc. This Time-like idea is uni-dimensional or elongate in a general or fluctuating sense; not specifically like I. It is in view of this characteristic, that it is broadly and primarily contrasted with the Spacic significance of o (aw), which is omnidimensional.
The two remaining Vowel-Sounds, the O and U (oo), repeat the o (aw) and u (uh), in a sense, but in a new and more refined stage or degree of development. The sound O is made at the front mouth—the locality the most openly in sight of any at which Sound is produced—by rounding the lips into an irregularly-circular, face-like, or disk-like presentation. The O Sound so produced denotes Presence, as of an object by virtue of its reflection of Light; and, hence, Light, Clearness, Purity, Reflection.
The U (oo in fool) is an obscured or impure pronunciation of the O. The lips are protruded as if to say O; but not being sufficiently so for the production of the pure Sound, the Sound actually given is mixed, or made turbid or thick. The U-Sound denotes accordingly Retiracy, Obscurity, Shade, Turbidity, Mixedness, or Impurity, as of Colors in a dim light, or as of Materials in a slime or plasma, etc.
Metaphysically, O denotes Pure Theory, the Abstract; and U (oo) signifies the Actual or Practical, the Tempic, the Concrete (the Temporal or Profane), which is always mixed with contingency.
Other Vowel-Sounds, shades more or less distinct of some one of these Leading Sounds, are interspersed by nature between these diatonic Sounds, like the half tones and quarter tones in Music. Two of these French eu and e muet modifications of u (uh) have been mentioned. Eu is modulated at the lips, and e muet at the middle mouth, but both have the general character of u (uh). The French U is a modification of the U (oo), of the Scale just given, but made finer, and approximating I (ee). The Italian O is a modification of o (aw). These four are the Leading Semi-tone Sounds; which along with a carry the Scale from Seven (7) diatonic up to twelve (12) chromatic. As they will be passed over for the present with this mere mention, the points of the Scale at which they intervene will not be now considered.
Discarding these minor shades of Sounds, the Leading Scale of Vowel-Sounds is augmented from Seven (7) or Eight (8) to Twelve (12) or Thirteen (13), by the addition of the following five (5) Diphthongs or Double Vowels. In respect to the quality of Sound, they are pronounced just as the Vowels of which they are composed would be if separated and succeeding each other. To make the Diphthong long, the two Sounds are kept quite distinct. To make it short, they are closely blended; as, AU (ah-oo), long; A[)U] (ahoo), short. With no diacretical mark they are pronounced ad libidum, or neither very long nor short.