NATURAL HISTORY. is 



of soils ! what inequalities in the surface ! Yet upon 

 an attentive observation, we* observe that the great 

 chains of mountains lie nearer the equator than the 

 poles ; that, in the old Continent, their direction is 

 more from east to west than from north to south. 

 And the figure and direction of these mountains which 

 appear most irregular, correspond so, that the promi- 

 nent angles of one mountain are constantly opposite to 

 the concave angles of the neighbouring mountain, and 

 of equal dimensions, whether they be separated by an 

 extensive plain or a small valley. I have remarked 

 that the opposite are almost always of the same height ; 

 and that mountains for the most part occupy the mid- 

 dle of continents, islands, and promontories, and that 

 they divide them by their greatest lengths. By trac- 

 ing the courses of the principal rivers, I find that their 

 direction is nearly perpendicular to the sea-coasts in- 

 to which they empty themselves, and that for the 

 greater part of their courses they follow the direction 

 of the mountains from which they take their rise. 

 The sea-coasts are generally bordered with earth and 

 sand accumulated by the waters of the sea, or swept 

 down by rivers. In opposite coast?, separated only 

 by small arms of the sea, the different strata are of 

 the same materials. Volcanoes never exist but in 

 high mountains ; a great number of them are entirely 

 extinguished ; some are connected with others by sub- 

 terraneous passages, and their eruptions pretty fre- 

 quently happen -at the same time. Similar communi- 

 cations subsist between certain lakes an 1 seas. Some 

 rivers disappear on a sudden and seem to precipitate 

 themselves into the bowe!s^ the earth. Certain in- 

 land seas, too, constantly receive from many rivers 

 prodigious quantities of water, and .-which, as their 



