Attempts to reduce all matter to forms of ether--Emission
and absorption phenomena show reciprocal action--
Laws of radiation--Radiation of gases--Production of
spectrum--Differences between light and sound variations
show difference of media--Cauchy's, Briot's, Carvallo's
and Boussinesq's researches--Helmholtz's and
Poincare's electromagnetic theories of dispersion.

Sec. 2. The Theory of Lorentz:--Mechanics fails
to explain relations between ether and matter--Lorentz
predicts action of magnet on spectrum--Zeeman's experiment
--Later researches upon Zeeman effect--
Multiplicity of electrons--Lorentz's explanation of
thermoelectric phenomena by electrons--Maxwell's and
Lorentz's theories do not agree--Lorentz's probably more
correct--Earth's movement in relation to ether.

Sec. 3. The Mass of Electrons: Thomson's and
Max Abraham's view that inertia of charged body due
to charge--Longitudinal and transversal mass--Speed
of electrons cannot exceed that of light--Ratio of
charge to mass and its variation--Electron simple
electric charge--Phenomena produced by its acceleration.

Sec. 4. New Views on Ether and Matter:
Insufficiency of Larmor's view--Ether definable
by electric and magnetic fields--Is matter all electrons?
Atom probably positive centre surrounded by
negative electrons--Ignorance concerning positive
particles--Successive transformations of matter probable
--Gravitation still unaccounted for.

CHAPTER XI

THE FUTURE OF PHYSICS

Persistence of ambition to discover supreme principle
in physics--Supremacy of electron theory at present
time--Doubtless destined to disappear like others--
Constant progress of science predicted--Immense field
open before it.

INDEX OF NAMES

INDEX OF SUBJECTS

CHAPTER I

THE EVOLUTION OF PHYSICS

The now numerous public which tries with some success to keep abreast
of the movement in science, from seeing its mental habits every day
upset, and from occasionally witnessing unexpected discoveries that
produce a more lively sensation from their reaction on social life, is
led to suppose that we live in a really exceptional epoch, scored by
profound crises and illustrated by extraordinary discoveries, whose
singularity surpasses everything known in the past. Thus we often hear
it said that physics, in particular, has of late years undergone a
veritable revolution; that all its principles have been made new, that
all the edifices constructed by our fathers ha