vibration (vibrashon)

[ = The late proceedings seem to be producing a decisive vibration in our favor. Jefferson, To James Madison, Correspondence, I. 300. Like the great cords of a harp, in loud and solemn vibra tions . Long fellow , Evangeline, ii. 4. In Virginia there had been a great vibration of opinion. Bancroft, Hist. Const., II. 354. in their state of equilibrium. In the case of a vibrating string or rod, the vibrations are distinguished as trans verse or longitudinal, according to the direction of the oscillating movement relatively to the length of the sonorous body. The term vibration is also applied to the motion (generally an elliptical revolution) which is produced among the particles of a fluid or ethereal medium when their equilibrium is disturbed by any impulse, by which means waves or undulations are caused. In all cases one complete vibration means the double movement of the particle or vibrating body to and fro about the position of equilibrium, while the movement forward and backward on one side only is a half-vibration. The laws of vibratory motion form the foundation of the theories devised by modern science to account for the phenomena of acoustics and optics. See sound5, and undulatory the ory of light (under light1, 1), also cuts under nodal and 80 no meter. The phenomena of polarisation demonstrated... that the vibrations of light take place at right angles to the direction of the rays. Lommel , Light (trans.), p. 351. 3. In med., same as fremitus.-4. In nat. hist., movement to and fro, especially when quick, 6745 continuous, regular, and of little amplitude; a quivering or shivering motion; tremulousne ; tremor: as, the vibration of aspen-leaves on their compre ed petioles in the breeze; the vibration of the ear-drum under sound-waves; the vibration of a fly's wings in flight. The word is also somewhat specifically applied to ciliary action, or the motion of microscopic bodies, as cilia, flagella, vibracula, vibrios, spermatic filaments, and the like, vibration being the most obvious activity of such objects, and a usual means of locomotion, of ingestion of food, etc.Amplitude of a simple vibration. See amplitude. Amplitude of vibration, the maximum excursion or displacement of a vibrating body or particle from a position of rest.- Free vibration, a vibration whose period depends only upon the nature and form of the vibrating body: used in contradistinction to forced vibration, when the period is more or le modified by some outside influence, as the vibrations of a neighboring body of slightly different pitch. - Fun i pendulous vibration. See fun i pendulous.-Harmonic vibration. Same as simple har monic motion (which see, under harmonic ). - Lateral vibration. See lateral. - Period of vibration, the shortest time between instants at which the displacement and velocity of the vibrating body are the same both in amount and in direction. - Phase of vibrations, the time elapsed at an an a umed of time since the pa age of the vibrat ing body through equilibrium divided by the complete period of vibration, this quotient being multiplied by 360°. vibrational (vi-bra's hon-al), a. [ The vibrational impulse may be given as nearly as po ible at the centre of the ma of air in the resonant box. Encyc. Brit ., XXIV. 242, note 1.