Page:Aspects of nature in different lands and different climates; with scientific elucidations (IA b29329668 0002).pdf/343

 remarkable of which we possess any certain knowledge since the death of the elder Pliny     228-235

Difference between volcanos with permanent craters; and the phenomena (very rarely observed within historic times) in which trachytic mountains open suddenly, emit lava and ashes, and reclose again perhaps for ever. The latter class of phenomena are particularly instructive to the geologist, because they recall the earliest revolutions of the oscillating, upheaved, and fissured surface of the globe. They led, in classical antiquity, to the view of the Pyriphlegethon. Volcanos are intermitting earth springs, indicating a communication (permanent or transient) between the interior and the exterior of our planet; they are the result of a reaction of the still fluid interior against the crust of the earth; it is therefore needless to ask what chemical substance burns, or supplies materials for combustion, in volcanos     235-238

The primitive cause of subterranean heat is, as in all planets, the process of formation itself, i.e. the forming of the aggregating mass from a cosmical gaseous fluid. Power and influence of the radiation of heat from numerous open fissures and unfilled veins in the ancient world. Climate (or atmospheric temperature) at that period very independent of the geographical latitude, or of the position of the planet in respect to the central body, the sun. Organic forms of the present tropical world buried in the icy regions of the north     238-241

Scientific Elucidations and Additions—p. 243 to p. 248.

Barometric measurements of Vesuvius. Comparison of the height of different points of the crater of Vesuvius     243-247

Increase of temperature with depth, 1° Reaumur for every 113 Parisian feet, or 1° of Fahrenheit for every 53·5 English feet. Temperature of the Artesian well at Oeynhausen's Bad (New