If the mind can control unconsciously the contraction of the muscles of the larynx, it can as easily control the tongue, the size of the throat, the pectoral muscles, and, in short, all the muscles that influence the voice. VITAL SLIDE. When the mind has separated one thought distinctly from the other main thoughts of the subject, and has become intensely attracted to it with a special desire to communicate it as distinct from the others to the minds of the hearers, all the muscles will act in a way to produce Vital Slide. This principle of Vital Slide may be illustrated by “The Forging of the Anchor.” When the mind becomes aroused with this selection there is in the quality of the voice something of the spirit of the fife, the drum, and the military movement. Swing in your strokes in order; let hand and foot keep time; Your blows make music sweeter far than any steeple’s chime; But while ye swing your sledges, sing, and let the burden be, The anchor is the royal king, and royal craftsmen we. It is the energy of the mind which causes the energy of the muscles. The energy of the contraction of the muscles causes the report of that energy in the voice. Under Vital Slide we consider the relation of the muscles of respiration to the vocal cords. There are two sets of respiratory muscles, the muscles of inspiration and the muscles of expiration. If the thought requires for expression an increase of vitality in the voice, the muscles of expiration contract more strongly, thus giving greater density to the air in the lungs. The air, being an elastic substance, in seeking egress or relief presses strongly against the vocal cords, which are forced apart with such energy as to give an expression of greater vitality to the tone produced. It is not necessary to exert the will consciously on the different muscles which act upon the vocal organs. It is not necessary to call the roll and say, “Triangularis sterni, Diaphragm, Abdominal muscles, Intercostals, contract! Abdominal muscles, you must contract only just enough to overcome the contraction of the diaphragm. Now, all together—one, two, three, contract!” One should not think anything about these muscles. He should be no more conscious of their action than he is of the beating of his heart. SLIDE IN VOLUME. In giving Volume of voice, the vocal aperture is made as open as it can be and still have the elements of speech definitely formed; and the vibrating column of air is guided through the aperture without being biased by it. The chief agents which guide the voice through this aperture are the sides of the throat and the tongue in its proper relation to the pharynx, hard palate, and soft palate. When we combine Slide with Volume there must be an exact relation between the contraction of the vocal cords and the proper position and action of these vocal organs.