52 NATURAL HISTORY, 



of salt contained in sea water is about l-40th part, 

 and the sea is nearly equally saline throughout at top 

 as at the bottom, under the line, and at the Cape of 

 Good Hope, although there are several parts, as on 

 the Mosambique G'oast, where it is salter than else- 

 where. It is also asserted not to be so saline under 

 the Arctic Zone, which may proceed from the great 

 quantity of snow, and the great rivers which fall into 

 those seas, and because the heat of the sun produces 

 but little evaporation there, in comparison of that pro- 

 duced in hot climates. 



There are rivers which lose themselves in the sands, 

 and others which seem to precipitate into the bowels 

 'of the earth : the Guadalquiver in Spain, the river of 

 Gottenburgh in Sweden, and the Rhine itself, lose 

 themselves in the earth. It is asserted, that in the 

 west part of St. Domingo, there is a mountain of a 

 considerable height, at the foot of which are several 

 large caverns that receive the rivers and brooks, 

 whose fall is heard seven or eight leagues off. The 

 rivers, however, which disappear in the earth are very 

 few ; and they seem not to descend very deep. And it 

 is probable that, like the Rhine, they lose themselves 

 by dividing and disappearing through a large surface 

 of sand, of which there are many examples in Afric a, 

 Persia, Arabia, &c. 



The rivers of the north carry down to the sea pro- 

 digious quantities of ice, which form those enormous 

 masses so dangerous to the mariner. Those in the 

 sea of Nova Zembla and in the straits of Waigat, 

 come from the Oby, and, perhaps, from the Jenisca, 

 and other great rivers in Siberia and Tartary : 

 those of Hudson's straits, from Ascension bay, into 

 which many rivers in North America empty them- 



