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PHILOSOPHICAL AND SCIENTIFIC LESSONS.
The Triumph of Chemical and Mechanical Philosophy.... 73
Difference between Chemical and Mechanical Changes... 75
All the Substances of Nature made up of few Materials. 77
MORAL AND INTELLECTUAL
OBSERVATIONS AND RULES FOR READING AND
MAN, of all animals, is possessed of speech. The most intelligent of the brute creation frequently astonish us by actions, which can proceed only from powers of intellect similar to our own: the faculty of speech, then, is the criterion of distinction between man and the brute creation. Reason, without language, would have remained in inactivity, its energies unexcited, and its faculties torpid. When the influence of language upon intellect is fully and maturely considered, it will be found, that the most brilliant discoveries in philosophy and science are derived from this source. If those whose genius has dazzled the world, had been deprived of the observations and researches of others, they would not, in all probability, have arisen above the level of the least cultivated and most uninformed. Take from man the use of speech, and of visible signs, and his intellectual faculties would be circumscribed within very narrow limits.
THE human voice is air sent out from the lungs, and so agitated and modified in its passage through the wind-pipe and larynx, as to be distinctly audible. The wind-pipe is that tube which, on
touching the fore part of our throat externally, we feel hard and uneven. It conveys air into the lungs, for the purpose of respiration and speech. It consists of cartilages, circular before, that they may resist external injury; but flattish on the opposite side, that they may not hurt the œsophagus, or gullet, which lies close behind, and is the tube which conveys food into the stomach. These cartilages are separated by fleshy membranes, by means of which the wind-pipe may be shortened or lengthened, and, when necessary, incurvated, without inconvenience. The upper part of the wind-pipe is called the larynx; it consists of four or five cartilages, that may be expanded or brought together by the agency of muscles, which operate all at the same time.
MECHANISM OF THE VOICE.
IN the middle of the larynx there is a small aperture called the glottis, through which the breath and voice are conveyed; but which, when we swallow, is covered by a lid called the epiglottis ; for if any part of our food get into the wind-pipe, by this passage, it occasions coughing till it is thrown out again. The best authors have determined that the human voice is produced by two semicircular membranes in the middle of the larynx, which form, by their separation, the aperture called glottis. The space between them is not more than the tenth of an inch in width; through which the breath, transmitted from the lungs, passes with considerable velocity. It gives, in its passage, a brisk vibrating motion to the membranous lips of the glottis, and thus forms the sounds called voice; this is strengthened and mellowed by reverberation from the palate and other cavities of the mouth and nostrils; and as these are better or worse adapted for reverberation, the voice is more or less harmonious.
PURITY and clearness of articulation will depend much upon the organs of speech. There are few persons, however, whose apparatus of speech is so nicely adjusted, as not to require attention to this particular. An imperfect articulation is a very serious defect, and every one should by use try to improve it. A good articulation consists in giving a clear, full, and deliberate utterance to the several simple and complex sounds. As Austin, in his Chironomia," beautifully observes,-"In just articulation, the words are not hurried over, nor melted together; they are neither abridged nor prolonged; they are not swallowed, nor are they shot from the mouth; neither are they trailed, and then suffered to drop unfinished but they are delivered from the lips, as beautiful coins are issued from the mint, deeply and accurately impressed, neatly struck by the proper organs, distinct, sharp, and perfectly finished."