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