54969@54969-h@54969-h-6.htm.html#Page_212" class="pginternal">212 Monochord or sonometer, the, 121 Motion, conveyed to the brain by the nerves, 31 —— sonorous motion. See Sound. Mouth, resonance of the, 241-242 Music, physical difference between noise and, 82, 117 —— a musical tone produced by periodic, noise by unperiodic, impulses, 83, 117 —— production of musical sounds by taps, 84, 117 —— —— by puffs of air, 89, 117 —— pitch and intensity of musical sounds, 90, 92, 117 —— description of the siren, 97 —— definition of an octave, 105 —— description of the double siren, 110 —— transmission of musical sounds through liquids and solids, 113 —— musical chords, 432-433 —— the diatonic scale, 432-433 —— See also Harmony. Musical-box, formation of the, 169, 197 N Nerves of the human body, motion conveyed by the, to the brain, 31 —— rapidity of impressions conveyed by, 31 note Newton, Sir Isaac, his calculation of the velocity of sound, 58 Nodes, 131-132 —— the nodes not points of absolute rest, 135 —— nodes of a tuning-fork, 175, 177 —— rendered visible, 177, 180 —— a node the origin of vibration, 251 Noise, physical difference between music and, 82, 117 O Octave, definition of an, 105 Organ-pipes, 219, 256 Organ-pipes, vibrations of stopped pipes, 221, 256 —— —— Pandean pipes, 224 —— —— open pipes, 224, 256, 260 —— state of the air in sounding-pipes, 227, 257 —— reeds and reed-pipes, 234 Otolites of the ear, 425 Overtones, definition of, 153 —— relation of the point plucked to the, 155 —— corresponding to the vibrations of a rod fixed at both ends, 165 —— of a tuning-fork, 177 —— rendered visible, 177, 179 —— of rods vibrating longitudinally, 207 —— of the siren, 415 —— influence of overtones on harmony, 429 P Pandean pipes, the, 213, 253, 256 —— —— of the air, 213, 256 —— —— of coal-gas, 216, 256 —— description of vowel-sounds, 240 —— Kundt’s experiments on sound-figures within tubes, 244-251, 259 —— new methods of determining velocity of sound, 247-251, 259 —— causes that obstruct the propagation of, 306 —— action of fog upon sound, 307 —— contradictory results of fog-signalling, 317 —— solution of contradictions of fog-signalling, 317-318 —— extraordinary case of acoustic opacity, 318 —— great change of acoustic transparency, 323 —— noise of battle unheard, 324 —— echoes from invisible acoustic clouds, 325, 375 —— report of Arago on the velocity of, 328 —— aËrial echoes of, 330 —— demonstration of reflection from gases, 332 —— reflection from vapors, 336 —— —— heated air, 337 —— echo from flame, 340 —— investigations of the transmission of sound through the atmosphere, 341 —— action of hail and rain, 341 —— action of snow, 344 —— passage through tissues, 345 —— —— artificial showers, 346 —— action of fog, 347 —— fluctuations of bells, 351-354 —— action of wind, 361 —— atmospheric selection, 365 —— law of vibratory motions in water and air, 377, 407 —— superposition of vibrations, 381 —— interference and coincidence of sonorous waves, 382-383, 407 —— extinction of sound by sound, 384, 407 —— theory of beats, 385, 408 —— action of beats on flame, 387 —— optical illustration of beats, 390, 408 —— various illustrations of beats, 397 —— resultant tones, 399, 409 —— —— conditions of their production, 400 —— —— experimental illustrations, 401 —— —— theories of Young and Helmholtz, 405-406 —— difference-tones and summation-tones, 405 —— combination of musical sounds, 4
ss="pginternal">170 —— his apparatus for the compounding of rectangular vibrations, 448 Whistles, range of, for fog-signals, 313 Wind, effect on sound, 361 Wires. See Strings Wood, velocity of sound transmitted through, 74 —— musical sounds transmitted through, 115 —— the claque-bois, 175 —— determination of velocity in wood, 211 Woodstock Park, echoes in, 56 Y Young, Dr. Thomas, his proof of the relation of the point of a string plucked to the overtones, 155 —— on the curves described by vibrating piano-wires, 160-161 —— his theory of resultant tones, 404
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