PART III．MAGNETISM
CHAPTER I．ELEMENTARY THEORY OF MAGNETISM
371．Properties of a magnet when acted on by the earth
372．Definition of the axis of the magnet and of the direction of magnetic force
373．Action of magnets on one another．Law of magnetic force
374．Definition of magnetic units and their dimensions
375．Nature of the evidence for the law of magnetic force
376．Magnetism as a mathematical quantity
377．The quantities of the opposite kinds of magnetism in a magnet are always
379．A magnet is built up of particles each of which is a magnet
381．Magnetization is of the nature of a vector
382．Meaning of the term 'Magnetic Polarization'
383．Properties of a magnetic particle
384．Definitions of Magnetic Moment， Intensity of Magnetization， and
385．Potential of a magnetized element of volume
386．Potential of a magnet of finite size．Two expressions for this potential， corresponding respectively to the theory of polarization， and to that of magnetic
387．Investigation of the action of one magnetic particle on another
389．Potential energy of a magnet in any field of force
390．On the magnetic moment and axis of a magnet
391．Expansion of the potential of a magnet in spherical harmonics
392．The centre of a magnet and the primary and secondary axes through
393．The north end of a magnet in this treatise is that which points north， and thesouth end that which points south．Boreal magnetism is that which is supposed to exist near the north pole of the earth and the south end of a magnet．Austral magnetism is that which belongs to the south pole of the earth and the north endof a magnet．Austral magnetism is considered positive
394．The direction of magnetic force is that in which austral magnetism tends to move， that is， from south to north， and this is the positive direction of magnetic linesof force．A magnet is said to be magnetized from its south end towards its north
CHAPTER II．MAGNETIC FORCE AND MAGNETIC INDUCTION
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PART IV ELECTROMAGNETISM