GEOGNOSY.
This important branch of natural history makes us acquainted with the structure, relative position, mate rials, and mode of formation of the mineral masses of which the crust of the earth is composed. The term geognosy is derived from the Greek words 7n, the earth, and 7vedc-is, knowledge. It has been confounded with orology, which instructs us regarding the physiognomy of mountains ; with geogony, which is purely hypothe tical, consisting of very abstract speculations regarding the original formation of the earth ; also with geology, which, however, has a more extensive signification, for the word ito-/05 comprehends the whole science, or ra tionale of any subject ; and therefore geognosy is only a branch of geology. Geology, indeed, according to Werner, comprehends not only geognosy, hut also geo graphy, hydrography, meteorology, and geogony.
The speculative part of geognosy engaged the atten tion of mankind at a very early period ; for we find that the priests of Egypt maintained the aqueous origin of the globe. From Egypt science passed into Greece ; and we learn that Thales, one of the most distinguished of the Grecian philosophers, taught the Neptunian view of the origin and formation of the earth, which he had become acquainted with during his residence in Egypt. Zeno, another learned Greek philosopher, maintained that fire was the prima materia, and that the earth was formed from the igneous element. But it would be vain to attempt an account of the various fanciful specu lations on the formation of the earth, proposed by an cient authors. These afford us no satisfactory informa tion, in regard to the materials and structure of the crust of the earth. Agricola, in Saxony, and that re markable man Bernard de Palissy, in France, were the first observers who proposed rational opinions respect ing the formation of minerals. But the universal devo tion to idle, useless, and pernicious scholastic discus sions, so prevalent at that time, and which continued for a long succeeding period, occasioned an almost total neglect of their observations and opinions. In the year 1740, De Maillet, who had resided long in Egypt, and who adopted the opinions of the ancient philosophers of that country, where he himself had witnessed how the waters, by the deposition of earthy matter, contributed to the magnitude of the earth, attempted a general ex planation of the formation of the globe. In his curious work, entitled Telliamed, (his own name reversed,) he maintains, that our globe is composed of strata, which have been successively deposited over each other by the sea, which gradually retired and uncovered the present continents. This opinion was adopted by Linnaeus, in
his amusing tract, entitled De Telluris habitabilis incre ment° ; and Buffon, in his splendid vision of the forma tion of the earth, inclines partially to this hypothesis ; for he considers the superficial strata of the globe as having been formed from water. But all these specu lations rested on a very insecure basis ; because the mi neralogy of no tract of country had hitherto been accu rately and scientifically examined. It was therefore idle to attempt to speculate on the formation of the earth with any prospect of success, when we were ignorant of the materials of which it is composed, and of their structures and modes of arrangement.
Tilias, a Swede, was one of the first naturalists who was aware of the utility and importance of such de scriptions; and, in the year 1750, he published several topographical descriptions, illustrative of districts in Sweden. This example was speedily followed, and, in the year 1736, Lehman, a German miner, published his celebrated work on secondary, or ficetz rocks, in which the distinction into primitive and secondary mountains is first proposed. \Vallcrius, professor of mineralogy at Upsal, by the publication of his system of mineralogy in 1778, and Gerhard, in his elementary work on mine rals, made us acquainted with the geognostical situation of many minerals. But of all the works of that period, the most important was the physical geography of Berg man, in which we find collected and disposed, in a luminous order, all the facts and observations hitherto published, in regard to the strata of the earth, and to mineral veins. Travellers now made the investigation of the strata of countries an object of particular atten tion. Pallas, who was employed by thc Russian gov ernment, in examining the natural productions of that vast empire, although the state of mineralogy at that period, and the rapidity of his journeys, prevented mi nute investigations, made many important gcognostical observations, and was the first who investigated with cart the numerous and striking fossil remains of ele phants, rhinoceroses, and other genera of the torrid zone, found buried under the icy soil of Siberia.