Contents. xi 



CHAPTER VIII. 

 MAXWELL. 



Page 



Gauss and Riemann on the propagation of electric actions, . . 268 



Analogies suggested by W. Thomson, .... 269 



Maxwell's hydrodynamical analogy, ..... 271 



The vector potential, ...... 273 



Linear and rotatory interpretations of magnetism, . . . 274 



Maxwell's mechanical model of the electromagnetic field, . . 276 



Electric displacement, ...... 279 



Similarity of electric vibrations to those of light, . . . 281 



Connexion of refractive index and specific inductive capacity, . 283 

 Maxwell's memoir of 1864, . . ... .284 



The propagation of electric disturbances in crystals and in metals, . 288 



Anomalous dispersion, ...... 291 



The Max well -Sellmeier theory of dispersion, . . . 292 



Imperfections of the electromagnetic theory of light, . . 295 



The theory of L. Lorenz, ...... 297 



Maxwell's theory of stress in the electric field, . . . 300 



The pressure of radiation, ...... 303 



Maxwell's theory of the magnetic rotation of light, . . . 307 



CHAPTER IX. 



MODELS OF THE AETHER. 



Analogies in which a rotatory character is attributed to magnetism, 310 



Models in which magnetic force is represented as a linear velocity, 311 

 Researches of W. Thomson, Bjerknes, and Leahy, on pulsating and 



oscillating bodies, ...... 316 



MacCullagh's quasi-elastic solid as a model of the electric medium, 318 

 The Hall effect, . . . . . .320 



Models of Riemann and Fitz Gerald, . . . . 324 



Vortex-atoms, . . . . . . .326 



The vortex-sponge theory of the aether : researches of W. Thomson, 



Fitz Gerald, and Hicks, , . . . . .327 



CHAPTER X. 



THE FOLLOWERS OF MAXWELL. 



Helmholtz and H. A. Lorentz supply an electromagnetic theory of 



reflexion, ....... 337 



Crucial experiments of Helmholtz and Schiller, . . . 338 



