EARTH. 



the avarice of man, had led him to pene- 

 trate as fur as his limited powers will per- 

 mit towards the centre, he had but few 

 opportunities of ascertaining, and that 

 only from analogy, how the different strata 

 of the earth was disposed, and connected 

 or held together by the vast masses of 

 stone, which may be called the bones of 

 this vast body. As scientific men were 

 gradually admitted to the knowledge of 

 the secrets of the earth by the exertions 

 of the miner, in the same proportion did 

 all ideas of a chaos vanish, and we are now 

 convinced, though their excavations are 

 mere punctures in the globe, that, were 

 it possible to penetrate through, it would 

 tend to prove that self-existing causes, 

 originating immediately from the Creator, 

 are constantly employed in preserving the 

 whole from derangement, and what we 

 term decay, which, in truth, is simply a 

 change of form, and not annihilation. 

 The celebrated miner, Agricola, was the 

 first who recorded the internal proper- 

 ties of the earth, between whose time and 

 that of Werner some discoveries were 

 made as to its structure ; Lehman formed 

 the idea of primitive and secondary clas- 

 ses of mountains. Cronstad conjectured 

 the age of several mineral repositories. 

 Hamilton, Dolomieu, and Spallanzani, 

 have gone to very successful and satisfac- 

 tory lengths in ascertaining the opera- 

 tions of volcanos, the nature of the ma- 

 terials which support them, and the sub- 

 stances they eject. Saussure has increased 

 our knowledge of rocks, Williams of the 

 independent formation of coal, and Wer- 

 ner has profited by every preceding ob- 

 servation, and, possessing a cultivated ge- 

 nius of his own, united them into a sys- 

 tem,which approaches nearer to the truth 

 than the nature of the subject would lead 

 us to expect. Unfortunately, the labour 

 and expense of penetrating to any great 

 depth into the earth ever has, and ever 

 must, limit our knowledge of the extent 

 of strata, and its similarity in different 

 latitudes ; but from the opportunities al- 

 ready afforded by mines, we are led to 

 conclude that those lines of matter spread 

 through vast spaces, if not throughout the 

 globe ; many theories have been attempt- 

 ed, to account for their varieties and ca- 

 pricious elevations and depressions from 

 a horizontal direction. Dr. Woodward, 

 who deeply considered the subject, sup- 

 poses all the terrestrial masses disposed in 

 strata to have been dissolved by the wa- 

 ters of the deluge, which subsiding, the 

 most ponderous fell to the bottom, and 

 the rest settled in gradations suited to 



their specific weights. This solution na- 

 turally disposes the strata uniformly ho- 

 rizontal, and he accounts for the breaks 

 in the lines and fissures every where ob- 

 servable, by the action of volcanos, earth- 

 quakes, &c. Sic. Buffon's fancies of cor- 

 ners torn from the sun by comets, and 

 the earth lignified by fire, barely deserve 

 notice, and make a disgraceful contrast 

 with Woodward's ingenious conjectures. 

 The surface of the earth is known by 

 every enlightened person to be composed 

 of a confused mass of vegetable, and, in 

 some slight degree, of animal substances, 

 below which, Jameson says, there are 

 four different kinds of structure : '* The 

 first is that which is to be observed in 

 hand specimens ; it is the smallest kind 

 of structure, and occurs in what are 

 termed mountain-rocks or stones. The 

 second kind of structure, or that of moun- 

 tain-masses, is more on the great scale, 

 and is not to be observed in hand speci- 

 mens, but only in single masses of rock. 

 To this structure belongs stratification, 

 and the seams of distirict concretions. 

 The third kind of structure is that of 

 rock formations, or those great masses of 

 which the crust of the earth is compos- 

 ed. To examine this kind of structure, 

 we must traverse considerable tracts of 

 country. The fourth kind of structure is 

 that of the earth itself, which is formed by 

 the junction of various formations. To 

 examine this structure, we must travel 

 through many countries." 



When, in passing through long tracts 

 of land, we observe loose rocks, firm 

 rocks, clay, sand, 8cc. &,c. in succession, 

 in those instances the strata of the earth 

 lay almost perpendicular, in large masses 

 of rocks, which present nearly a plain 

 front, the inclination of the strata is dis- 

 tinctly visible, and in some cases their 

 agreement with others opposed to them 

 demonstrate, that they have been se- 

 parated by some convulsion of the 

 earth. 



The gravity of a portion of the earth 

 was calculated by Dr. Maskelyne in the 

 years 1774 and 1775, at the mountain 

 Schehallien, and its attraction on a plum- 

 met ascertained on each side; besides 

 which, he computed the quantity of mat- 

 ter contained in it by a considerable num- 

 ber of sections in various directions ; and 

 the result being afterwards compared with 

 the acknowledged magnitude and attrac- 

 tion of the earth, v he found that the den- 

 sity was as 9 to 5 of common stone, and 

 as 9 to 2 water ; whence it was inferred 

 that large quantities of metal lay conceal- 



