Calendar: 1889-1890 Page 408

404 EVENING CLASSES II -Reflection of Sound Echoes Refraction of Sound Communication of Vibrations The Tuning-fork Relation between the Rate of Vibration and the Pitch of Sound The Siren III -Vibrations of Strings The Monochord Harmonic Division of Strings Stringed Instruments Effects of Length and Tension IV -Vibrations of Rods Plates and Membranes Re lation of the Mode of Vibration to the Pitch of the Note Reed Instruments Combinations of Sounds -Intensity of Sound Vibration of Columns of Air Resonance Organ Pipes Singing Flames In- terference of Sound Beats Optical Represent tion of Vibratory Motion VI -The Propagation of Light Methods of Measuring its Intensity Theory of Shadows Velocity Light Aberration The Undulatory Theory VII -Reflection of Light from Plane and Curved Surfaces The Heliostat Caustics formed by Reflection Refraction of Light Total Reflection Atmo- spheric Refraction Prisms VIII -Measurement of Indices of Refraction Lenses Composition of White Light The Solar Spectrum The Oxy-hydrogen Light The Electric Light IX -Spectra of Incandescent Solids Liquids and Gas Absorption of Light Constitution of the Sun and of various Fixed Stars Heat Light and Chemical Rays of the Spectrum -Emission of Light The Cause of Co our in Bodies Optical Instruments The Eye and Vision Irra- diation