CONTENTS. ix 



SECTION XXV. 



Heat Calorific Rays of the Solar Spectrum Experiments of MM. De 

 Laroche and Melloui on the Transmission of Heat The Point of greatest 

 Heat in the Solar Spectrum varies with the Substance of the Prism 

 Polarization of Heat Circular Polarization of Heat Transmission of the 

 Chemical Rays Absorption of Heat Radiation of Heat Dew Hoar 

 Frost Rain Hail Combustion Dilatation of Bodies by Heat Propa- 

 gation of Heat Latent Heat Heat presumed to consist of the Undula- 

 tions of an Elastic Medium Parathermic Rays Moser's Discoveries 



Page. 906 



SECTION XXVI. 



Atmosphere of the Planets and the Moon Constitution of the Sun Esti- 

 mation of the Sun's Light His Influence on the different Planets 

 Temperature of Space Internal Heat of the Earth Zone of Constant 

 Temperature Heat increases with the Depth Heat in Mines and 

 Wells Thermal .Springs Central Heat Volcanic Action The Heat 

 above the Zone of Constant Temperature entirely from the Sun The 

 Quantity of Heat annually received from the Sun Isogeothermal Lines 

 Distribution of Heat on the Earth Climate Line of Perpetual Con- 

 gelation Causes affecting Climate Isothermal Lines Excessive Cli- 

 mates The same Quantity of Heat annually received and radiated by 

 the Earth 238 



SECTION XXVII. 



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 202 



SECTION XXVIIL 



Of ordinary Electricit 



iry Electricity, generally called Electricity of Tension Methods 

 of exciting Bodies Transference Electrics and Non- Electrics Law of 

 its Intensity Distribution Tension Electric Heat and Light Atmos- 

 pheric Electricity Its Cause Electric Clouds Back Stroke Violent 

 Effects of Lightning Its Velocity Phosphorescence Phosphorescent 

 Action of Solar Spectrum Aurora 271 



SECTION XXIX. 



Voltaic Electricity The Voltaic Battery Intensity Quantity Compari- 

 son of the Electricity of Tension with Electricity in Motion Luminous 

 Effects Decomposition of Water Formation of Crystals by Voltaic 

 Electricity Electrical Fish 290 



SECTION XXX. 



Terrestrial Magnetism Magnetic Poles Lines of equal and no Variation 

 ' The Dip The Magnetic Equator Magnetic Intensity Secular, peri- 

 odic, and transitory Variations in the Magnetic Phenomena Origin of 

 the Mariner's Compass Natural Magnets Artificial Magnets Polarity 

 Induction Intensity Hypothesis of two Magnetic Fluids Distribu- 

 tion of the Magnetic Fluid Analogy between Magnetism and Elec- 

 tricity .300 



