Page:Aspects of nature in different lands and different climates; with scientific elucidations (IA b29329668 0002).pdf/221

 ON THE

STRUCTURE AND MODE OF ACTION

OF

VOLCANOS,

IN DIFFERENT PARTS OF THE GLOBE.

[This dissertation was read in a public assembly of the Academy at Berlin, on the 24th of January, 1823.]

When we reflect on the influence which, for some centuries past, the progress of geography and the multiplication of distant voyages and travels have exercised on the study of nature, we are not long in perceiving how different this influence has been, according as the researches were directed to organic forms on the one hand, or on the other to the study of the inanimate substances of which the earth is composed—to the knowledge of rocks, their relative ages, and their origin. Different forms of plants and animals enliven the surface of the earth in every zone, whether the temperature of the atmosphere varies in accordance with the latitude and with the many inflections of the isothermal lines on plains but