CONTENTS. 21 



first Law of Gravitation 110 



Knowledge of Extension - - - - - - -111 



Muscular Feeling, its Measure ...... 112 



Second Law of Gravitation - - 113 

 Specific Gravity Variations of Gravity .... 114 



Gravitation of Distance ....... H6 



Importance of Gravitation --. 117 

 The FIRST CAUSE ........ 119 



SECTION V. 



LIGHT AND HEAT. 



What Substance is 121 



Cohesion 122 



Consistency of Matter - - - - - - -123 



Presses, Pressure, and Resistance ..... 124 



Motion of Light and Heat 125 



Opposing Motions Collision ...... 126 



Fineness of Light ... .... 127 



Shadows Their Effect - - - - * * -128 



Light of the Sun 130 



Culture of Plants - - - * - 130 



Rainbow and Colours ....... 133 



Vegetable Colours 134 



Heat Its Degrees ........ 136 



Electricity Lightning Thunder 138 



Moonlight Its Changes and Effects 140 



Lapland Moon 142 



Ignis Fatuus ......... 144 



Phosphorescence Glow-worms ..... 144 



Action of Heat 146 



Heat and Motion ........ 149 



Heat irresistible 150 



Seasonal Heat 151 



Elasticity ". . -152 



Heat and Resistance 153 



Blasting Rocks 154 



Volcanic Action 154 



SECTION VL 



AIR AND WATER. 



Light and Heat not known as Substances - - -157 



Nature of Air 158 



Air a State of Matter 158 



