The New Physics and Its Evolution | Page 3

Nichols' experiments--Hertzian and light rays contrasted--Pressure of light.
§ 5. The X-Rays: R?ntgen's discovery--Properties of X-rays--Not homogeneous--Rutherford and M'Clung's experiments on energy corresponding to--Barkla's experiments on polarisation of--Their speed that of light--Are they merely ultra-violet?--Stokes and Wiechert's theory of independent pulsations generally preferred--J.J. Thomson's idea of their formation-- Sutherland's and Le Bon's theories--The N-Rays-- Blondlot's discovery--Experiments cannot be repeated outside France--Gutton and Mascart's confirmation-- Negative experiments prove nothing--Supposed wave-length of N-rays.
§ 6. The Ether and Gravitation: Descartes' and Newton's ideas on gravitation--Its speed and other extraordinary characteristics--Lesage's hypothesis--Crémieux' experiments with drops of liquids--Hypothesis of ether insufficient.

CHAPTER VII
WIRELESS TELEGRAPHY
§ 1. Histories of wireless telegraphy already written, and difficulties of the subject.
§ 2. Two systems: that which uses the material media (earth, air, or water), and that which employs ether only.
§ 3. Use of earth as return wire by Steinheil --Morse's experiments with water of canal--Seine used as return wire during siege of Paris--Johnson and Melhuish's Indian experiments--Preece's telegraph over Bristol Channel--He welcomes Marconi.
§ 4. Early attempts at transmission of messages through ether--Experiments of Rathenau and others.
§ 5. Forerunners of ether telegraphy: Clerk Maxwell and Hertz--Dolbear, Hughes, and Graham Bell.
§ 6. Telegraphy by Hertzian waves first suggested by Threlfall--Crookes', Tesla's, Lodge's, Rutherford's, and Popoff's contributions--Marconi first makes it practicable.
§ 7. The receiver in wireless telegraphy--Varley's, Calzecchi--Onesti's, and Branly's researches-- Explanation of coherer still obscure.
§ 8. Wireless telegraphy enters the commercial stage-- Defect of Marconi's system--Braun's, Armstrong's, Lee de Forest's, and Fessenden's systems make use of earth-- Hertz and Marconi entitled to foremost place among discoverers.

CHAPTER VIII
THE CONDUCTIVITY OF GASES AND THE IONS
§ 1. The Conductivity of Gases: Relations of matter to ether cardinal problem--Conductivity of gases at first misapprehended--Erman's forgotten researches--Giese first notices phenomenon--Experiment with X-rays-- J.J. Thomson's interpretation--Ionized gas not obedient to Ohm's law--Discharge of charged conductors by ionized gas.
§ 2. The Condensation of water-vapour by Ions: Vapour will not condense without nucleus--Wilson's experiments on electrical condensation--Wilson and Thomson's counting experiment--Twenty million ions per c.cm. of gas--Estimate of charge borne by ion-- Speed of charges--Zeleny's and Langevin's experiments--Negative ions 1/1000 of size of atoms--Natural unit of electricity or electrons.
§ 3. How Ions are Produced: Various causes of ionization--Moreau's experiments with alkaline salts--Barus and Bloch on ionization by phosphorus vapours--Ionization always result of shock.
§ 4. Electrons in Metals: Movement of electrons in metals foreshadowed by Weber--Giese's, Riecke's, Drude's, and J.J. Thomson's researches--Path of ions in metals and conduction of heat--Theory of Lorentz--Hesehus' explanation of electrification by contact--Emission of electrons by charged body-- Thomson's measurement of positive ions.

CHAPTER IX
CATHODE RAYS AND RADIOACTIVE BODIES
§ 1. The Cathode Rays: History of discovery--Crookes' theory--Lenard rays--Perrin's proof of negative charge--Cathode rays give rise to X-rays--The canal rays--Villard's researches and magneto-cathode rays-- Ionoplasty--Thomson's measurements of speed of rays-- All atoms can be dissociated.
§ 2. Radioactive Substances: Uranic rays of Niepce de St Victor and Becquerel--General radioactivity of matter--Le Bon's and Rutherford's comparison of uranic with X rays--Pierre and Mme. Curie's discovery of polonium and radium--Their characteristics--Debierne discovers actinium.
§ 3. Radiations and Emanations of Radioactive Bodies: Giesel's, Becquerel's, and Rutherford's Researches--Alpha, beta, and gamma rays--Sagnac's secondary rays--Crookes' spinthariscope--The emanation --Ramsay and Soddy's researches upon it--Transformations of radioactive bodies--Their order.
§ 4. Disaggregation of Matter and Atomic Energy: Actual transformations of matter in radioactive bodies --Helium or lead final product--Ultimate disappearance of radium from earth--Energy liberated by radium: its amount and source--Suggested models of radioactive atoms--Generalization from radioactive phenomena -Le Bon's theories--Ballistic hypothesis generally admitted--Does energy come from without--Sagnac's experiments--Elster and Geitel's contra.

CHAPTER X
THE ETHER AND MATTER
§ 1. The Relations between the Ether and Matter: 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 Poincaré's electromagnetic theories of dispersion.
§ 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.
§ 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.
§ 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