SOUND

The Nerves and Sensation—Production and Propagation of Sonorous Motion—Experimentson Sounding Bodies placed in Vacuo—Deadening ofSound by Hydrogen—Action of Hydrogen on the Voice—Propagationof Sound through Air of Varying Density—Reflection of Sound—Echoes—Refractionof Sound—Diffraction of Sound; Case of ErithVillage and Church—Influence of Temperature on Velocity—Influenceof Density on Elasticity—Newton’s Calculation of Velocity—ThermalChanges Produced by the Sonorous Wave—Laplace’sCorrection of Newton’s Formula—Ratio of Specific Heats at ConstantPressure and at Constant Volume deduced from Velocities ofSound—Mechanical Equivalent of Heat deduced from this Ratio—Inferencethat Atmospheric Air Possesses no Sensible Power to RadiateHeat—Velocity of Sound in Different Gases—Velocity in Liquids andSolids—Influence of Molecular Structure on the Velocity of Sound.

Physical Distinction between Noise and Music—A Musical Tone Producedby Periodic, Noise Produced by Unperiodic, Impulses—Production ofMusical Sounds by Taps—Production of Musical Sounds by Puffs—Definitionof Pitch in Music—Vibrations of a Tuning-Fork; theirGraphic Representation on Smoked Glass—Optical Expression of theVibrations of a Tuning-Fork—Description of the Siren—Limits ofthe Ear; Highest and Deepest Tones—Rapidity of Vibration Determinedby the Siren—Determination of the Lengths of Sonorous Waves—Wave-Lengthsof the Voice in Man and Woman—Transmission ofMusical Sounds through Liquids and Solids.

Vibration of Strings—How employed in Music—Influence of Sound-Boards—Lawsof Vibrating String—Combination of Direct and ReflectedPulses—Stationary and Progressive Waves—Nodes and Ventral Segments—Applicationof Results to the Vibrations of Musical Strings—Experimentsof Melde—Springs set in Vibration by Tuning-Forks—Lawsof Vibration thus demonstrated—Harmonic Tones of Strings—Definitionsof Timbre or Quality, or Overtones and Clang—Abolitionof Special Harmonies—Conditions which affect the Intensity of theHarmonic Tones—Optical Examination of the Vibrations of a Piano-Wire