Influence of travels in distant lands on the generalization of our ideas and on the progress of physical orology. Influence of the conformation of the Mediterranean on the earliest ideas respecting volcanic phenomena.—Comparative Geology of Volcanos. Periodical return of certain revolutions in nature, the cause of which lies deep in the interior of the globe. Proportion of the height of volcanos to that of their cone of ashes in the Pichincha, Peak of Teneriffe, and Vesuvius. Changes in the height of volcanic mountain summits. Measurements of the margins of the crater of Vesuvius from 1773 to 1822; the author’s measurements embrace the period from 1805 to 1822—pp. [353]–365. Circumstantial description of the eruption in the night between the 24th and 25th of October, 1822. Falling in of a cone of ashes more than 400 feet high, which stood in the interior of the crater. The eruption of ashes from the 24th to the 28th of October, was the most memorable among those, of which authentic accounts are possessed, since the time of the elder Pliny—pp. [365]–371.
Difference between volcanos that are of very diverse forms, with permanent craters, and the phenomena more rarely observed in historic times, in which trachytic mountains suddenly open, eject lava and ashes, and reclose, perhaps for ever. The latter phenomena are peculiarly instructive for geognosy, because they remind us of the earliest revolutions that occurred in the oscillating, upheaved, fissured surface of the earth. In ancient times they led to the notion of the Pyriphlegethon. Volcanos are intermittent earth-springs, the result of a permanent or transitory connection between the interior and exterior of our planet, the result of a reaction of the still fluid interior against the crust of the earth; hence the question is useless, as to what chemical substance burns in the volcanos, and furnishes the material for combustion—pp. [371]–373. The primary cause of subterranean heat is, as in all planets, the formative process itself, the separation of the conglomerating mass from a cosmic vaporous fluid. Power and influence of the calorific radiation from numerous deep fissures, unfilled veins in the primordial world. Great independence, at that period, of the climate (atmospheric temperature) in respect to geographical latitude, the position of the planet towards the central body, the sun. Organisms of the present tropical world buried in the icy north—pp. [373]–375.
| Scientific Illustrations and Additions | pp. [376]–379. |
Barometric measurements on Vesuvius, comparison of the two crater-margins and the Rocca del Palo—pp. [376]–379. Increase of temperature with depth, being 1° of Fahrenheit for every 54 feet. Temperature of the Artesian well in Oeynhausen’s Bath (New Salt-works near Minden), at the greatest depth yet reached below the level of the sea. As early as the third century the thermal springs near Carthage led Patricius, Bishop of Pertusa, to form correct suppositions respecting the cause of calorific increase in the interior of the earth—p. [379].
| VITAL FORCE, OR THE RHODIAN GENIUS; AN ALLEGORY. | pp. [380]–385. |
| Illustrations and Note | pp. [386]–389. |
The Rhodian Genius is the development of a physiological idea in a mythical garb. Difference of views concerning the necessity and nonnecessity for the assumption of peculiar vital forces—pp. [386]–387. The difficulty of satisfactorily reducing the vital phenomena of the organism to physical and chemical laws is, principally, based on the complexity of the phenomena, on the multiplicity of forces acting simultaneously, as well as on the varying conditions of their activity. Definition of the expressions, animate and inanimate matter. Criteria of the miscent state ensuing upon separation, are the simple enunciation of a fact—pp. [387]–389.
| THE PLATEAU OF CAXAMARCA, THE ANCIENT CAPITAL OF THE INCA ATAHUALLPA, AND FIRST VIEW OF THE PACIFIC FROM THE RIDGE OF THE ANDES. | pp. [390]–420. |
Cinchona, or Quina-woods in the valleys of Loxa. First use of the fever-bark in Europe; the Vice-Queen Countess of Chinchon—pp. [390]–392.
Alpine vegetation of the Paramos. Ruins of ancient Peruvian causeways; they rise in the Paramo del Assuay almost to the height of Mont Blanc—p. [394]. Singular mode of communication, by a swimming courier—p. [399].
Descent to the Amazon River. Vegetation around Chamaya and Tomependa; red groves of Bougainvillæa. Rocky ridges which cross the Amazon River. Cataracts. Narrows of the Pongo de Manseriche, in which the mighty stream, measured by La Condamine, is hardly 160 feet broad. Fall of the rocky dam of Rentema, which for several hours, laid bare the bed of the river, to the terror of the inhabitants on its banks—p. [401].