Chapter I: Preface

For thirty years or more the expressions "Correlation of the Physical Forces" and "The Conservation of Energy" have been common, yet few persons have taken the necessary pains to think out clearly what mechanical changes take place when one form of energy is transformed into another.

Since Tyndall gave us his book called _Heat as a Mode of Motion_ neither lecturers nor text-books have attempted to explain how all phenomena are the necessary outcome of the various forms of motion. In general, phenomena have been attributed to _forces_--a metaphysical term, which explains nothing and is merely a stop-gap, and is really not at all needful in these days, seeing that transformable modes of motion, easily perceived and understood, may be substituted in all cases for forces.

In December 1895 the author gave a lecture before the Franklin Institute of Philadelphia, on "Mechanical Conceptions of Electrical Phenomena," in which he undertook to make clear what happens when electrical phenomena appear. The publication of this lecture in _The Journal of the Franklin Institute_ and in _Nature_ brought an urgent request that it should be enlarged somewhat and published in a form more convenient for the public. The enlargement consists in the addition of a chapter on the "_Contrasted Properties of Matter and the Ether_," a chapter containing something which the author believes to be of philosophical importance in these days when electricity is so generally described as a phenomenon of the ether.

A. E. DOLBEAR.

TABLE OF CONTENTS

CHAPTER I

Ideas of phenomena ancient and modern, metaphysical and
mechanical--Imponderables--Forces, invented and
discarded--Explanations--Energy, its factors, Kinetic
and Potential--Motions, kinds and transformations
of--Mechanical, molecular, and atomic--Invention of
Ethers, Faraday's conceptions p. 7

CHAPTER II

Properties of Matter and Ether compared--Discontinuity
_versus_ Continuity--Size of atoms--Astronomical
distances--Number of atoms in the universe--Ether
unlimited--Kinds of Matter, permanent qualities
of--Atomic structure; vortex-rings, their
properties--Ether structureless--Matter
gravitative, Ether not--Friction in Matter, Ether
frictionless--Chemical properties--Energy in
Matter and in Ether--Matter as a transformer
of Energy--Elasticity--Vibratory rates and
waves--Density--Heat--Indestructibility of
Matter--Inertia in Matter and in Ether--Matter
not inert--Magnetism and Ether waves--States
of Matter--Cohesion and chemism affected by
temperature--Shearing stress in Solids and in
Ether--Ether pressure--Sensation dependent upon
Matter--Nervous system not affected by Ether
states--Other stresses in Ether--Transformations
of Motion--Terminology p. 24

CHAPTER III

Antecedents of Electricity--Nature of what is
transformed--Series of transformations for the
production of light--Positive and negative
Electricity--Positive and negative twists--Rotations
about a wire--Rotation of an arc--Ether a
non-conductor--Electro-magnetic waves--Induction
and inductive action--Ether stress and atomic
position--Nature of an electric current--Electricity
a condition, not an entity p. 94