Mode of propagation. Illustrations. Air or other medium necessary for transmission; no sound through vacuum.
Sounds differ in loudness, pitch, quality.
Physical cause of loudness.—Violence of vibration.
Physical cause of pitch.—Rapidity of vibration. Siren, or perforated disc.
Strings.—Note given depends on length, thickness, tension and material. Experiments with monochord. Illustrate by violin strings.
Harmonics.—Subdivision of strings. Experiment with riders on string.
Physical cause of “quality”.—Intermixture of other notes with fundamental.
Resonance.—Experiments with tubes of air and tuning-forks. Organ pipes.
Velocity of sound.—How first determined. Calculate distance of thunderstorm.
Reflection.—Echoes.