The whistle, which plays the part of the larynx, is necessarily placed opposite the opening of the bellows, and a sort of tourniquet M is fastened to the opening itself, which is able to move on certain conditions, so that it may produce the rolling sound of _r_. This is done by fastening before the opening a diaphragm in which there is a somewhat wide and long slit, and this slit can be almost closed by a little bar of the same size M, revolving on a transverse axis which supports it by its centre. In its normal condition, this little bar is kept in a slanting position by cords attached to the keyboard, and the air ejected by the bellows readily traverses the slit in order to reach the larynx; but two dampers are fastened to the rods which transmit movement, with which the cords just mentioned are also connected. On lowering the notes of the key-board, the passage of air is contracted, and the little plate begins to oscillate and to press against a band of leather, producing by its vibration an action similar to that produced by the cricket. This little tourniquet only begins to act when the dampers are lowered by a pedal worked by the hand; and this is also the case with the iron rod _t_, which modifies the acuteness of the sounds passing through the larynx.[22] Below the larynx tube, which is only five centimètres in length, there is another pipe G, also of caoutchouc, which terminates in a spherical cavity connected with the outer air by a caoutchouc tube I, slightly raised, and closed by a valve, of which the movements are regulated by a pedal worked by the keyboard. When the valve is open, the sounds emitted through the larynx are somewhat nasal.[23] The larynx communicates with the mouth through a square funnel-shaped pipe, to which six metallic diaphragms D are fastened; the diaphragms are placed in a vertical position behind each other, and have indentations on their lower end, which are intended to diminish more or less the orifice for the current of air, and to impede its passage with greater or less force. The diaphragms, which we represent separately fig. 74, are connected with the keyboard by jointed iron rods _t_, and, for the emission of most articulate sounds, several of the diaphragms are moved at the same moment and at different heights. We shall return to this subject. [Illustration: FIG. 74.]