CONTENTS. VJi 



SECTION XI. - 



Precession and Nutation Their Effects on the Apparent Places of the 

 Fixed Stars Page 74 



SECTION XII. 



Mean and Apparent Sidereal Time Mean and Apparent Solar Time 

 Equation of Time English and French Subdivisions of Time Leap 

 Year Christian Era Equinoctial Time Remarkable Eras depending 

 upon the Position of the Solar Perigee Inequality of the Lengths of 

 the Seasons in the two Hemispheres Application of Astronomy to Chro- 

 nology English and French Standards of Weights and Measures 77 



SECTION XIII. 



Tides Forces that produce them Three kinds of Oscillations in the Ocean 

 The Semidiurnal Tides Equinoctial Tides Effects of the Declina- 

 tion of the Sun and Moon Theory insufficient without Observation 

 Direction of the Tidal Wave Height of Tides Mass of Moon obtained 

 from her Action on the Tides Interference of Undulations Impossi- 

 bility of a Universal Inundation Currents . . . . . 85 



SECTION XIV. 



Repulsive Force Interstices or Pores Elasticity Mossotti's Theory 

 Gravitation brought under the same law with Molecular Attraction and 

 Repulsion Gases reduced to Liquids by Pressure Intensity of the Co- 

 hesive Force Effects of Gravitation Effects of Cohesion Minuteness 

 of the ultimate Atoms of Matter Limited Height of the Atmosphere 

 Theory of Definite Proportions and Relative Weight of Atoms Dr. Far- 

 aday's Discoveries with regard to Affinity Composition of Water by a 

 Plate of Platina Crystalization Cleavage Isomorphism Matter con- 

 sists of Atoms of Definite Form Capillary Attraction . 96 



SECTION XV. 



Analysis of the Atmosphere Its Pressure Law of Decrease in Density 

 Law of Decrease in Temperature Measurement of Heights by the 

 Barometer Extent of the Atmosphere Barometrical Variations Oscil- 

 lations Trade Winds Monsoons Rotation of Winds Laws of Hur- 

 ricanes Water-Spouts Ill 



SECTION XVI. 



Sound Propagation of Sound illustrated by a Field of Standing Corn 

 Nature of Waves Propagation of Sound through the Atmosphere 

 Intensity Noises A Musical Sound Quality Pitch Extent ^of 

 Human Hearing Velocity of Sound in Air, Water, and Solids Causes 

 of the Obstruction of Sound Law of its Intensity Reflection of Sound 

 Echoes Thunder Refraction of Sound Interference of Sounds 122 



SECTION XVII. 



Vibration of Musical Strings Harmonic Sounds Nodes Vibration of Air 

 in Wind Instruments Vibration of Solids Vibrating Plates Bells- 

 Harmony Sounding- Boards Forced Vibrations Resonance Speaking 

 Machines . 134 



