viii CONTENTS 



ART. PAGE 



79. Waves generated by Vibrating Solid 236 



80. Communication of Vibrations to a Gas .... 237 



81. Scattering of Sound Waves by an Obstacle . . . 240 



82. Transmission of Sound by an Aperture .... 244 



83. Contrast between Diffraction Effects in Sound and Light. 



Influence of Wave-Length . . . . . "''.'!. 248 



CHAPTER IX 



PIPES AND RESONATORS 



84. Normal Modes of Rectangular and Spherical Vessels . 254 



85. Vibrations in a Cylindrical Vessel 259 



86. Free Vibrations of a Resonator. Dissipation . . . 260 



87. Corrected Theory of the Organ Pipe 266 



88. Resonator under Influence of External Source. Reaction 



on the Source ... . . . t v, . . 270 



89. Mode of Action of an Organ Pipe. Vibrations caused by 



Heat . . . . 276 



90. Theory of Reed-Pipes . . . . . . . . 278 



CHAPTER X 



PHYSIOLOGICAL ACOUSTICS 



91. Analysis of Sound Sensations. Musical Notes . . . 284 



92. Influence of Overtones on Quality 286 



93. Interference of Pure Tones. Influence on the Definition 



of Intervals . . . 287 



94. Helmholtz Theory of Audition . . . . . . 289 



95. Combination-Tones 292 



96. Influence of Combination-Tones on Musical Intervals ' . 297 



97. Perception of Direction of Sound . . . ' . . 298 



INDEX . 301 



