[ 303 ] 



much higher, and confequently. better fitted for colleding vapours 

 than at prefent, but in modern times, from the extenfion of agricul- 

 ture to countries where it never before was introduced, and the 

 increafmg muhiphoation of mankind, the forefts have in great 

 meafure difappeared ; the earth laid bare yields its waters to eva- 

 poration ; the mountains lowered, no longer colled or condenfe the 

 fame quantity of vapour, the rivulets ceafe, or are reduced to 

 rills, and the earth freed from its pervading moifture has naturally 

 funk to a lower level. Hence moft rivers were anciently much 

 more confiderable than at prefent, as we may fee by the wide ex- 

 tended 'vales through which they run, the monuments of their 

 ancient magnitude. Not only bogs have in fome inftances been 

 known to Aide over lower adjacent plains, but even portions of 

 land feemingly more folid. Thus in France near Meudon in 1787 

 a whole fide of a hill covered with trees defcended 50 feet upon 

 and covered to the height of 70 feet a neighbouring plain ; its 

 defcent lafted fix years. 43 Roz. 19. It was occafioned by laying 

 bare a bed of clay which by imbibing rain was tumefied and loofcn- 

 cd. In Bohemia alfo, fo late as the year 1770, a great part of the 

 mountain of Ziegenberg flid down 38 fathom to the Elbe with its 

 trees flill flanding partly ered and partly inclined. This was 

 afcribed to the folution of its inferior ftratum, an argillaceous 

 fandflone, whofe argillaceous part was carried off by rain to which 

 it had incautioufly been expofed. Reufs Bohemia, 55. 



In 



