Jalve

1. (Ger. Ventil’; Fr. piston; It. val'vola, pis to’ne.) In certain bra wind-instr.s, a device for diverting the air-current from the main tube to an additional side-tube, thus Jeng thening the air-column and lowering the pitcl of the instrument's entire scale. By the aid of valves, xatura/ instr.s are a8 VARIA MENT altered to chromatic instr.s commanding ‘a chromatic scale throughout their compa . (Compare Horn, Trumpet; also Key 3,)—The valves are operated by the fingers of the right hand; their usual number is 3, No. 1 lowering the pitch by (approximately) x tone, No. 2 by a semitone, and No. 3 by 1 tones. ‘wo systems are in ordinary use; the Piston-valve, and the Rotary Valve.— (2) The Pisten-valve is a cylindrical plunger working in an air-tight cylinder, terminating in a short rod surmounted by a button, and pierced cro wise by 2 round holes; the enclosing cylinder is similarly pierced, on either side, one perforation Suwon with the main tube, the other with the side-tube. ‘When the piston is not depre ed, one of its holes is opposite to those in the cylinder which communicate with the main tube, so that the open (natural) tone of the tube can be sounded; on depre ing the piston with the finger, communication with the main tube is cut off, but opened with the side-tube, so that the lower tone sounds. On releasing the piston, a spiral spring causes its return to the original poetoe: —The Rotary Valve is ‘a four-way; stop-cock turning in a cylindrical case ‘ in the plane of the instrument, 2 of its 4 ways forming part of the main channel, the other 2, on its rotating through a quadrant of the circle, admitting the air to the vide-tube”. Its manipulation is lighter than that of the piston, but it is more liable to derangement.—z. In the organ, the principal valves are the suction-valves or suckers admitting wind to the bellows and preventing its escape; the waste-pallet, relieving the bellows of an over-supply of wind; and the Aey-valves or pallets.