• • 



Xll 



CONTENTS OF THE EIEST VOLUME 



Atmosphere was subcharged with Carbonic Acid in the Coal Period — Fossil 

 Shells and Corals of the Carboniferous Strata — Climate implied by the Reptiles 

 or Amphibia of the Coal — Devonian Period, and supposed Signs of Ice- action of 

 that Era considered — Climate of the Silurian Period — Concluding Remarks on 

 the Climates of the Tertiary, Secondary, and Primary Epochs page 212 



CHAPTER XII. 



VICISSITUDES IN CLIMATE CAUSED BY GEOGRAPHICAL CHANGES. 



On the Causes of Vicissitudes in Climate — On the present Diffusion of Heat OTer 

 the Globe — Mean Annual Isothermal Lines — Dependence of the Mean Tempera- 

 ture on the relative Position of Land and Sea — Climate of South Georgia and 

 Tierra del Fuego — Cold of the Antarctic Region — Open Sea near the North Pole 

 -Effect of Currents in equalising the Temperature of High and Low Latitudes 

 The present Proportion of Polar land abnormal — Succession of Geographical 

 Changes revealed to us by Geology — Map showing the Amount of European 

 Land which has been under Water since the Commencement of the Eocene 

 p er i d — Antiquity of the existing Continents — Changes in Geography which 

 preceded the Tertiary Epoch — Map showing the unequal Distribution of Land 

 and Water on the Globe — Eormer Geographical Changes which may have 

 caused the Fluctuations in Climate revealed to us by Geology — Ideal Map with 

 the Excess of Land removed from Polar to Tropical Eegions — Great Depth of 

 the Sea as compared to the Mean Height of the Land, and its Connection with 



the Slowness of Climatal Changes 



233 



CHAPTEE XIII. 



VICISSITUDES IN CLIMATE HOW FAR INFLUENCED BY 



ASTRONOMICAL CHANGES. 



The Precession of the Equinoxes, and Variations in the Excentricity of the Earth s 



■ 



Orbit considered as affecting Climate — Under what Conditions Extreme Ex- 

 centricity may exaggerate Cold — Measurement of Heat — Temperature of Space 

 — Climates of Successive Phases of Precession — Variation in the Obliquity of 

 the Ecliptic — Eadiation of Heat impeded by a covering of Snow — Quantity of 

 Polar Ice and its Influence in altering the Level of the Ocean —Migrations of 

 the Greenland "Whale — Liquefaction and Evaporation of Snow — How far the 

 Dates of former Glacial Periods may be fixed by computing the Eras of Maxi- 

 mum Excentricity— Dates of the Neolithic and Paleolithic Eras— Of the Inten- 

 sity of Glacial Cold— Duration of the Glacial Period as compared to Successive 

 Tertiary, Secondary, and Primary Epochs — Supposed Variations in the Tempe- 

 rature of Space— Solar Magnetic Periods and Variable Splendour of the Stars- 

 Supposed gradual Diminution of the Earth's Primitive Heat— Supposed Change 

 in the Position of the Axis of the Earth's Crust 268 







CHAPTEE XIV. 



UNIFORMITY IN THE SERIES OF PAST CHANGES IN THE 



ANIMATE AND INANIMATE WORLD. 



Supposed alternate Periods of Eepose and Disorder— Observed Facts in which 

 this Doctrine has originated— These may be explained by supposing a uniform 



