CONTENTS. 



INTRODUCTION 



SECTION I. 



Attraction of a Sphere Form of Celestial Bodies Terrestrial Gravitation 

 retains the Moon in her Orbit The Heavenly Bodies move in Conic 

 Sections Gravitation Proportional to Mass Gravitation of the Particles of 

 Matter Figure of the Planets How it affects the Motions of their Satel- 

 litesRotation and Translation impressed by the same Impulse Motion of 

 the Sun and Solar System 5 



SECTION II. 



Elliptical Motion Mean and True Motion Equinoctial Ecliptic Equi- 

 noxes Mean and True Longitude Equation of ' Centre Inclination of 

 the Orbits of Planets Celestial Latitude Nodes Elements of an Orbit- 

 Undisturbed or Elliptical Orbits Great Inclination of the Orbits of the 

 New Planets Universal Gravitation the Cause of Perturbations in the Mo- 

 tions of the Heavenly Bodies Problem of the Three Bodies Stability of 

 Solar System depends upon the Primitive Momentum of the Bodies . 10 



SECTION III. 



Perturbations, Periodic and Secular Disturbing Action equivalent to three 

 Partial Forces Tangential Force the cause of the Periodic Inequalities in 

 Longitude, and Secular Inequalities in the Form and Position of the Orbit 

 in its own Plane Radial Force the cause of Variations in the Planet's Dis- 

 tance from the Sun It combines with the Tangential Force to produce 

 the Secular Variations in the Form and Position of the Orbit in its own 

 Plane Perpendicular Force the cause of Periodic Perturbations in Lati- 

 tude, and Secular Variations in the Position of the Orbit with regard to the 

 Plane of the Ecliptic Mean Motion and Major Axis Invariable Stability 

 of System Effects of a Resisting Medium Invariable Plane of the Solar 

 System and of the Universe Great Inequality of Jupiter and Saturn . 15 



