EARTH, the vast mass or planet we inhabit. The scientific and theoretical attempts which have been made to ascer tain the form and internal composition of the earth, have produced less certain re sults than could be wished. With re spect to the grand outline we may con clude, without much danger of error, that it is spherical ; which observation is sup ported by the appearance of the moon, the nearest body to the earth. We may illustrate this supposition by drawing a true circle, and filling its circumference with a capricious outline, sometimes touching and at others receding from it. The cause of the inequalities, which we denominate mountains and valfies, seems to be the natural consequences of the composition of the earth, the action of the air and water ever chapging the posi tion of the softer materials, and having but little effect on the hardest. Thus, on the borders of the sea, large tracts of land are known to crumble into it, and that even mountains are under mined: Mont Blanc has recently afford ed a most melancholy proof. Besides the above causes, there are others volcanic, and arising from the earthquakes pro duced by them. Still greater changes in the surface of the earth have taken place at periods beyond the records of history, except in the single instance of the scriptures and the deluge, which is demonstrated by the discovery of sub stances, evidently peculiar to the sea only, in the highest mountains, where it is impossible to account for their ar rival, but by supposing that the spots where they are found were raised by strong internal pressure from the cen tre, under the bottom of the sea, which doubtlessly presents a surface very simi lar to the parts we inhabit.
Before the invention of instruments calculated to ascertain geographical doubts with precision, and the circum navigation of the globe, the ancients ima gined the earth fiat or"cylindrical ; but the moderns with greater truth, derived from superior means, pronounce it al most spherical, founding their opinion upon the following just grounds; the cir cular shadow of the earth in eclipses of the moon, the general appearance of the planetary system in all parts of the earth being the same, and the observations made in circumnavigating it concurring with those which must result from a glo bular form. That great philosopher, Sir Isaac Newton, was led by accident to suppose from the revolving of the earth round its axis, and the laws of hydros tatics, that it is an oblate spheroid, flat tened at the poles. Professor Jameson admits the truth of this supposition, and says, " The spheroidal figure of the earth is a proof of its original fluidity. This important conclusion was never disputed ; the only question has been, whether this fluidity was the effect of fire or water. Rocks, which have been formed or alter ed by the action of heat, are most dis tinctly different from those that consti tute the great mass of the crust of the globe ; consequently, this fluidity cannot be attributed to the agency of heat." Whether the conjectures on the opposite hypothesis are founded on a tenable basis, cannot be ascertained to demonstration ; but it may not be amiss to let the Pro fessor speak further on the subject.
"The only other agent we are acquaint ed with, that is capable of producing this fluidity, is water ; and we have the strong est evidence that it has been the active agent. In chap. 2, when mentioning the effects of water on the surface of the globe, we described several mechanical and chemical depositions which are daily taking place, as it were, under the eye ; and we may now add, that a comparison of their structure, with that of the great fossil masses of which the crust of the earth is composed, evinces so complete an agreement, as entitles us to infer, with great certainty, that these also have been formed by the same agent. As the high est mountains are composed of rocks, possessing a structure resembling those fossils which have been formed by water, we naturally conclude, that the ocean must have formerly stood very high over these mountains. Further, as the most elevated mountains are composed of rocks, such as granite, gneiss, mica-slate, clay slate, and others, which extend around the whole globe, and have been formed during the same period of time ; it fol lows irresistibly, that the ocean must have formerly covered the whole earth at the same time." In order to clear the surface of the earth of this superabundance of water, which militates against the existence of life but in one species of the animated system, and equally against every species of vegetation, our theorist observes, " It was reserved for Werner to give this theory stability. With his usual acute he soon discovered that the impor tant documents for the illustration of this great phenomenon were not to be sought fbr in the formations that have taken place within the limits of human history, but in the mountains themselves, those mighty aquatic formations. His investiga tions were attended with complete suc cess; for he discovered, 1st, That the outgoings of the newer strata are gene rally lower than the outgoings of the older, from granite downwards to the alluvial depositions, and this not in par ticular spots, but around the whole globe. 2nd, That the primitive part of the earth is entirely composed of chemical preci pitations, and that mechanical depositions do not appear until a later period, that is, in the transition class ; and that from this point they continue increasing, through all the succeeding classes of rocks, to the newest, or the alluvial, which are almost entirely mechanical deposits. These most important observations ascer tain, in a satisfactory manner, the univer sal diminution of the water from the sur face of the earth." To obviate the difficulty above noticed, the Professor supposes animals to have been created as the earth was cleared to receive them; but the superfluous water is still in want of a receptacle capacious enough to contain it: such are the unfor tunate consequwices of theory. Newton has certainly proceeded upon the best data, and his calculations are almost uni versally correct and convincing.