EBB AND FLOW. 201 



The first is that there is found a manifest motion and 

 flow of waters from the Indian ocean, even to the Atlantic, 

 and that more swift and strong towards the Straits of Ma 

 gellan, when an outlet is opened to them westwards ; and 

 a great current also on the other side of the world from the 

 northern ocean to the British sea. And these currents of 

 waters manifestly roll from east to west ; in which fact we 

 must note in the first place, that in those two places alone 

 the seas find thoroughfares, and can describe in flowing a 

 complete circle : whereas, on the contrary, at the central 

 regions of the globe, by the two ramparts of the old and 

 new world, they are thrown off and driven (as it were into 

 the estuaries of rivers) into the basins of the Atlantic and 

 Pacific, the two oceans extending between the south and 

 north, and open to the motion of a current from east to west. 

 So that the true course of the waters is most safely inferred 

 from the extremities of the globe, as we have stated, where 

 they meet with no impediment, but sweep round in full 

 circuit. And the first experiment is thus, the second is the 

 following. 



Let us suppose that the tide takes place at the mouth of 

 the Straits of Gibraltar at any given hour: it is certain that 

 the tide sets in at Cape St. Vincent later in the day than 

 at the mouth of the Straits, at Cape Finisterre later than 

 at Cape St. Vincent, at King s Island later than at Cape 

 Finisterre, at the Island Heek later than at King s 

 Island, at the entrance of the English channel later 

 than at Heek, at the shore of Normandy later than at 

 the entrance of the channel. Thus far in regular order : 

 but at Graveling, as if by an entire inversion of the order, 

 and that with a great leap as it were, at the same hour, 

 with a velocity like that which it has at the mouth of the 

 Straits of Gibraltar. This second observation we apply to, 

 and compare with, the first. For we think, as has already 

 been said, that in the Indian and northern oceans the true 

 currents of the waters, that is from the east to the west, are 

 open and unimpeded, but in the channels of the Atlantic 

 and southern oceans imprisoned and crossing, and rever 

 berated by the interposition of lands, which extend both 

 ways longitudinally from south to north ; and no where 

 but toward their extremities afford a free canal to the waters. 

 But that strong direction of the waters, which is caused by 

 the Indian ocean towards the north, and in the opposite 

 direction from the north sea towards the south, differ infi 

 nitely in the extent of sea, affected on account of the diffc- 



