Vibrations of a Rod fixed at Both Ends: its Subdivisions and Corresponding Overtones—Vibrations of a Rod fixed at One End—The Kaleidophone—The Iron Fiddle and Musical Box—Vibrations of a Rod free at Both Ends—The Claque-bois and Glass Harmonica—Vibrations of a Tuning-Fork: its Subdivisions and Overtones—Vibrations of Square Plates—Chladni’s Discoveries—Wheatstone’s Analysis of the Vibrations of Plates—Chladni’s Figures—Vibrations of Disks and Bells—Experiments of Faraday and Strehlke. 165 SUMMARY OF CHAPTER IV 196 CHAPTER V Longitudinal Vibrations of a Wire—Relative Velocities of Sound in Brass and Iron—Longitudinal Vibrations of Rods fixed at One End—Of Rods free at Both Ends—Divisions and Overtones of Rods vibrating longitudinally—Examination of Vibrating Bars by Polarized Light—Determination of Velocity of Sound in Solids—Resonance—Vibrations of Stopped Pipes: their Divisions and Overtones—Relation of the Tones of Stopped Pipes to those of Open Pipes—Condition of Column of Air within a Sounding Organ-Pipe—Reeds and Reed-Pipes—The Voice—Overtones of the Vocal Chords—The Vowel Sounds—Kundt’s Experiments—New Methods of determining the Velocity of Sound. 200 SUMMARY OF CHAPTER V 254 CHAPTER VI Singing Flames—Influence of the Tube surrounding the Flame—Influence of Size of Flame—Harmonic Notes of Flames—Effect of Unisonant Notes on Singing Flames—Action of Sound on Naked Flames—Experiments with Fish-Tail and Bat’s-Wing Burners—Experiments on Tall Flames—Extraordinary Delicacy of Flames as Acoustic Reagents—The Vowel-Flame—Action of Conversational Tones upon Flames—Action of Musical Sounds on Smoke-Jets—Constitution of Water-Jets—Plateau’s Theory of the Resolution of a Liquid Vein into Drops—Action of Musical Sounds on Water-Jets—A Liquid Vein may compete in Point of Delicacy with the Ear 260 SUMMARY OF CHAPTER VI 301 CHAPTER VII _PART I_ RESEARCHES ON THE ACOUSTIC TRANSPARENCY OF THE ATMOSPHERE IN RELATION TO THE QUESTION OF FOG-SIGNALLING Introduction—Instruments and Observations—Contradictory Results from the 19th of May to the 1st of July inclusive—Solution of Contradictions—Aërial Reflection and its Causes—Aërial Echoes—Acoustic Clouds—Experimental Demonstration of Stoppage of Sound by Aërial Reflection 305 _PART II_ INVESTIGATION OF THE CAUSES WHICH HAVE HITHERTO BEEN SUPPOSED EFFECTIVE IN PREVENTING THE TRANSMISSION OF SOUND THROUGH THE ATMOSPHERE Action of Hail and Rain—Action of Snow—Action of Fog; Observations in London—Experiments on Artificial Fogs—Observations on Fogs at the South Foreland—Action of Wind—Atmospheric Selection—Influence of Sound-Shadow 341