xiv CONTENTS. 



SECTION XXVI. 



Influence of Temperature on Vegetation Vegetation varies with the Lati- 

 tude and Height above the Sea Geographical Distribution of Land 

 Plants Distribution of Marine Plants Corallines, Shell-fish, Reptiles, 

 Insects, Birds, and Quadrupeds Varieties of Mankind, yet identity of 

 Species Page 248 



SECTION XXVII. 



Terrestrial Heat Radiation Transmission Melloni's experiments 

 Heat in Solar Spectrum Polarization of Heat Nature of Heat 

 Absorptions Dew Rain Combustion Expansion Compensa- 

 tion Pendulum Transmission through Crystals Propagation 

 Dynamic Theory of Heat Mechanical equivalent of Heat Latent 

 Heat is the Force of Expansion Steam Work performed by Heat 

 Conservation of Force Mechanical Power in the Tides Dynamical 

 Power of Light Analogy between Light, Heat, and Sound . . 257 



SECTION XXVIII. 



Common or Static Electricity, or Electricity of Tension A Dual Power 

 Methods of exciting it Attraction and Repulsion Conduction 

 Electrics and Non-electrics Induction Dielectrics Tension Law 

 of the Electric Force Distribution Laws of Distribution Heat of 

 Electricity Electrical Light and its Spectrum Velocity Atmos- 

 pheric Electricity Its cause Electric Clouds Violent effects of 

 Lightning Back Stroke Electric Glow Phosphorescence . . 282 



SECTION XXIX. 



Voltaic Electricity The Voltaic Battery Intensity Quantity Static 

 Electricity, and Electricity in Motion Luminous Effects Mr. Grove 

 on the Electric Arc and Light Decomposition of Water Formation 

 of Crystals by Voltaic Electricity Photo-galvanic Engraving Con- 

 duction Heat of Voltaic Electricity Electric Fish 297 



SECTION XXX. 



Discovery of Electro-magnetism Deflection of the Magnetic Needle by a 

 Current of Electricity Direction of the Force Rotatory Motion by 

 Electricity Rotation of a Wire and a Magnet Rotation of a Magnet 

 about its Axis Of Mercury and Water Electro-Magnetic Cylinder 

 or Helix Suspension of a Needle in a Helix Electro-Magnetic Induc- 

 tion Temporary Magnets The Galvanometer 312 



