CONTENTS

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Introduction .. \

CHAPTER I.

Early notions of Physical Astronomy.—Newton.—His first Researches on the sub-ject of Gravitation.—Cause of his failure_Correspondence with Hooke.—

Resumption of his previous Researches_Law of the Areas.—Motion of a

Body in an Elliptic Orbit, the force tending to the Focus.—Picard.—His Measure-ment of an Arc of the Meridian.— Complete success of Newton’s Investigationrelative to the Action of the Earth upon the Moon ..—His establishment of thePrinciple of Gravitation in its widest generality.—Consequences he derived fromit.-—The Principia.—Account of the circumstances connected with its publication.

—Halley , Hooke , Wren.—Synopsis of the subjects treated of in the Principia.—Laplace’s opinion of its merits.15

CHAPTER II.

Newton’s Intellectual Character considered in connection with his Scientific Re-searches.—His Inductive ascent to the Principle of Gravitation. —Motion of aBody in an Orbit of Variable Curvature.—Attraction of a Spherical Mass ofParticles.—Developement of the Theory of Gravitation,—General Effects ofPerturbation.—Inequalities of the Moon computed.—Aid afforded by the Infini-tesimal Calculus.—Figure of the Earth.—Attraction of Spheroids.—Precession ofthe Equinoxes.—General accuracy of Newton’s Results.—Anecdotes illustrativeof his Natural Disposition.—His Death and Interment.33

CHAPTER III.

Circumstances which impeded the early progress of the Newtonian Theory.—Its

reception in England_Reception on the Continent.—Huygens, Leibnitz.—

Researches in Analysis and Mechanics. —Their influence on Physical Astronomy.

•—Problem of Three Bodies_Motion of the Lunar Apogee.—Clairaut.—Lunar

Tables.—Mayer.41

CHAPTER IV.

Perturbations of the Planets.—Inequality of Long Period in the Mean Motionsof Jupiter and Saturn.—Researches of Euler.—Perturbations of the Earth.—

Clairaut.—Perturbations of Venus—Lagrange His investigation of the Problem

of Three Bodies.—Secular Variations of the Planets.—Laplace.—His Researches