K alone, or with the additional characters, would suggest Ga, NG, Sh, J French, A, E, and L, with a mark for orisonance.
F alone, or with a mark for sonisibilance, V.
Th alone, or with a mark for sonisibilance, Th.
H alone, or with a mark for sonisibilance, Ch Spanish, and with a mark for less open vocality, aw, with another for more open vocality ah.
Whence it appears that six single characters, for the letters P, T, K, F, Th, H, with seven additional marks joined to them for antesonance, narisonance, orisonance, sibilance, sonisibilance, less open vocality, and more open vocality; being in all but thirteen characters, may spell all the European languages.
I have found more difficulty in analyzing the vowels than the other letters; as the apertures, through which they are modulated, do not close; and it was therefore less easy to ascertain exactly, in what part of the mouth they were modulated; but recollecting that those parts of the mouth must be more ready to use for the purpose of forming the vowels, which were in the habit of being exerted in forming the other letters; I rolled up some tin foil into cylinders about the size of my finger; and speaking the vowels separately through them, found by the impressions made on them, in what part of the mouth each of the vowels was formed with somewhat greater accuracy, but not so as perfectly to satisfy myself.
The parts of the mouth appeared to me to be those in which the letters P, I, K, and H, are produced; as those, where the letters F and Th are formed, do not suit the production of mute or antesonant consonants; as the interstices of the teeth would occasion some sibilance; and these apertures are not adapted to the formation of vowels on the same account.
The two first vowels aw and ah being modulated in the back part of the mouth, it is necessary to open wide the lips and other passages of the mouth in pronouncing them; that those passages may not again alter their tone; and that more so in pronouncing ah, than aw; as the aperture of the fauces is opened wider, where it is formed, and from the greater or less size of these apertures used in forming the vowels by different persons, the tone of all of them may be somewhat altered as spoken by different orators.
I have treated with greater confidence on the formation of articulate sounds, as I many years ago gave considerable attention to this subject for the purpose of improving shorthand; at that time I contrived a wooden mouth with lips of soft leather, and with a valve over the back part of it for nostrils, both which could be quickly opened or closed by the pressure of the fingers, the vocality was given by a silk ribbon about an inch long and a quarter of an inch wide stretched between two bits of smooth wood a little hollowed; so that when a gentle current of air from bellows was blown on the edge of the ribbon, it gave an agreeable tone, as it vibrated between the wooden sides, much like a human voice. This head pronounced the p, b, m, and the vowel a, with so great nicety as to deceive all who heard it unseen, when it pronounced the words mama, papa, map, and pam; and had a most plaintive tone, when the lips were gradually closed. My other occupations prevented me from proceeding in the further construction of this machine; which might have required but thirteen movements, as shown in the above analysis, unless some variety of musical note was to be added to the vocality produced in the larynx; all of which movements might communicate with the keys of a harpsichord or forte piano, and perform the song as well as the accompaniment; or which if built in a gigantic form, might speak so loud as to command an army or instruct a crowd.
I conclude this with an agreeable hope, that now war is ceased, the active and ingenious of all nations will attend again to those sciences, which better the condition of human nature; and that the alphabet will undergo a perfect reformation, which may indeed make it more difficult to trace the etymologies of words, but will much facilitate the acquisition of modern languages; which as science improves and becomes more generally diffused, will gradually become more distinct and accurate than the ancient ones; as metaphors will cease to be necessary in conversation, and only be used as the ornaments of poetry.