NATURAL HISTORY. 43 



Hence this earth, which appears to us to he crossed and 

 cut hy the enormous height of the mountains, and by 

 the frightful depth of the sea, is, when we consider its 

 size, so very slightly furrowed with irregularities, that 

 they can make no variation upon its general figure. 



Upon the continents the mountains are continued, 

 and form chains. In islands they appear to be more 

 interrupted and isolated, and generally raised above the 

 sea, in form of a cone or pyramid, and are called peaks. 

 The peak of Teneriffe is one of the highest mountains 

 on the earth ; it is near a mile and a half high perpen- 

 dicular from the level of the sea ; the peak of St George 

 in one of the Azores, and the peak of Adam in the 

 island of Ceylon, are also exceedingly high. All these 

 peaks are composed of rocks, piled one above ansther, 

 which emit each from their summits, fire, cinders, 

 bitumen, minerals, and stones. There are even islands 

 which are precisely only as tops of mountains, as the 

 island of St Helena, Ascension, most of the Azores, 

 and Canaries : and we must remark, that in most of 

 the islands, promontories, and other projecting lands 

 in the sea, the middle is always the highest, and they 

 are generally separated by chains of mountains, which 

 divide them in their greatest length ; as the Grampian 

 mountains in Scotland, which extend from east to west, 

 and divide Great Britain into two parts ; it is the same 

 with the islands Sumatra, Lucon, Borneo, Celebes, 

 Cuba, and St Domingo, and also Italy, which is tra- 

 versed through its whole length by the Appenines. 



With respect to the depths on the surface of the earth, 

 those of the ocean are, no doubt, the greatest, but 

 as these can only be discovered by sounding, we shall 

 take notice of none but such as appear on the dry land. 

 The precipices then which are between rocks, are form- 



