CHAPTER VI.

HEAT--SOLAR AND TERRESTRIAL.

Solar and Terrestrial Heat--Position of the Earth in the Solar System--Heat and Light associated in the Sunbeam--Transparency of Bodies to Heat--Heating Powers of the Coloured Rays of the Spectrum--Undulatory Theory--Conducting Property of the Earth’s Crust--Convection--Radiation--Action of the Atmosphere on Heat Rays--Peculiar Heat Rays--Absorption and Radiation of Heat by dissimilar Bodies--Changes in the Constitution of Solar Beam--Differences between Transmitted and Reflected Solar Heat--Phenomena of Dew--Action of Solar Heat of the Ocean--Circulation of Heat by the Atmosphere and the Ocean--Heat of the Earth--Mean Temperature--Central Heat--Constant Radiation of Heat Rays from all Bodies--Thermography--Action of Heat on Molecular Arrangements--Sources of Terrestrial Heat--Latent Heat of Bodies--Animal Heat--Eremacausis--Spheroidal State Cold--Condensation--Freezing--Theories of Heat--Natural Phenomena--and Philosophical Conclusion 62