On the Connexion of the Physical Sciences

Transcriber’s Note


When italics were used in the original book, the corresponding text has
been surrounded by _underscores_ except in the case of single letter
variables used in the Notes section, where the italics were not
represented. Mixed fractions have been displayed with a hyphen between
whole number and fraction for clarity. Superscripted characters are
preceded by ^ and when more than one character is superscripted, they
are surrounded by {}. This book uses some unusual characters, such as
those representing the constellation Aries (♈) and Libra (♎). These
characters may fail to display correctly if the font you are using does
not support them.

Some corrections have been made to the printed text. These are listed in
a second transcriber’s note at the end of the text.




[Illustration:

  MARY SOMERVILLE
  J. COOPER S^c.
]




                                   ON

                             THE CONNEXION

                                   OF

                         THE PHYSICAL SCIENCES.

                          BY MARY SOMERVILLE,

              AUTHORESS OF ‘MECHANISM OF THE HEAVENS,’ AND
                         ‘PHYSICAL GEOGRAPHY.’

                         ---------------------

“No natural phenomenon can be adequately studied in itself alone—but, to
be understood, it must be considered as it stands connected with all
Nature.”—BACON.

                         ---------------------

                   Ninth Edition, completely Revised.




                                LONDON:
                     JOHN MURRAY, ALBEMARLE STREET.
                                 1858.

                _The right of Translation is reserved._




  LONDON: PRINTED BY W. CLOWES AND SONS, DUKE STREET, STAMFORD STREET,
                           AND CHARING CROSS.




                         This Book is Dedicated

                                   TO

                           HER DEAR CHILDREN,

                     BY THEIR AFFECTIONATE MOTHER,

                                                        MARY SOMERVILLE.

_Florence, Nov. 1, 1858._




                               CONTENTS.


INTRODUCTION

                                                                  Page 1


                               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
  Satellites—Rotation and Translation impressed by the same
  Impulse—Motion of the Sun and Solar System

                                                                       4


                              SECTION II.

Elliptical Motion—Mean and True
  Motion—Equinoctial—Ecliptic—Equinoxes—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 Motions of the Heavenly
  Bodies—Problem of the Three Bodies—Stability of Solar System depends
  upon the Primitive Momentum of the Bodies

                                                                       8


                              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 Distance 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 Latitude, 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

                                                                      13


                              SECTION IV.

Theory of Jupiter’s Satellites—Effects of the Figure of Jupiter upon his
  Satellites—Position of their Orbits—Singular Laws among the Motions of
  the first Three Satellites—Eclipses of the Satellites—Velocity of
  Light—Aberration—Ethereal Medium—Satellites of Saturn and Uranus

                                                                      27


                               SECTION V.

Lunar Theory—Periodic Perturbations of the Moon—Equation of
  Centre—Evection—Variation—Annual Equation—Direct and Indirect
  Action of Planets—