CHAPTER IX AETHER AND MAGNETISM ART. 86 . ELECTRO-MAGNETISM 192 " 87 . THE EARTH A MAGNET 195 " 88 . THE SUN AN ELECTRO-MAGNET 199 " 89 . FARADAY'S LINES OF FORCE 203 " 90 . TERRESTRIAL MAGNETISM 206 " 91 . SOLAR MAGNETS 211 " 92 . CAUSE OF ROTATION OF THE EARTH ON ITS AXIS 219 " 93 . VORTEX MOTION 221 " 94 . RELATIVE MOTION OF AETHER AND MATTER 224 " 95 . VIBRATIONS IN THE ELECTRO-MAGNETIC THEORY OF LIGHT 228