INDEX OF SUBJECTS. 647 



PART III. MAGNETISM. 

 CHAPTER I. PRELIMINARY. 



PAGE 



On Magnets 280 



Magnets Natural and Artificial, Permanent and Temporary 280 



Magnetic and Diamagnetic Substances 281 



Distribution of Magnetism in Magnets. Poles 281 



The Two Kinds of Magnetism 282 



Law of Magnetic Actions 282 



Magnetic Masses 283 



Magnetic Field 284 



Definition of Poles. Magnetic Axis of a Magnet 284 



The Magnetic Mass of a Magnet is Zero 285 



Magnetic Moments 285 



Action of a Uniform Field on a Magnet 287 



Astatic Systems 287 



Magnetic Polarity. Rupture of a Magnet 288 



Induced Magnetisation 288 



Soft Iron. Coercive Force 289 



Influence of Temperature 290 



On Magnetic Fluids 290 



Definition of Terrestrial Magnetic Elements 291 



Distribution of Terrestrial Magnetism 294 



Hypothesis of a Terrestrial Magnet 294 



Variations of Terrestrial Magnetism 296 



CHAPTER II. CONSTITUTION OF MAGNETS. 



Magnetic Filaments 298 



Free Magnetism 298 



Uniform Magnet 299 



Any Given Magnet 299 



Potential of a Magnet 299 



A Magnet is Equivalent to a Magnetic Surface 300 



Poisson's Theory , 301 



Sir W. Thomson's Theory 302 



Intensity of Magnetisation 302 



Expression for Potential 303 



Uniform Magnets 305 



