TrtE EARTH 179 



wnn], which is more powerful during the tune of the flux thati 

 r!io retiux. 



But this motion westward has been sensibly observed by n;- 

 vig;ators, in their passage back from India to Madagascar, and 

 so on to Africa. In the great Pacific Ocean also it is very 

 perceivable ; but the places where it is most obvious, are, as 

 vvas said, in those straits which join one ocean to another. In 

 t)ie straits between the Maldivia islands, in the gulf of Mexi- 

 co, between Cuba and Jucatan. In the straits of the gulf of 

 Paria, the motion is so violent, that it hath received the appel- 

 lation of the Dragon's Mouth. Northward, in the sea of 

 Canada, in Waigat's straits, in the straits of Java, and, in short, 

 in every strait where the ocean on one part pours into the ocean 

 on the other. In this manner, therefore, is the sea carried with 

 an unceasing circulation round the globe ; and at the same time 

 that its waters are pushed backward and forward with the tide, 

 they have thus a progressive current to the west, which though 

 less obser^'able, is not the less real. 



Beside these two general motions of the sea, there are others 

 which are particular to many parts of it, and are called currents. 

 These are found to run in all directions, east, west, north, and 

 south ; being formed, as was said above, by various causes ; the 

 prominence of the shores, the narrowness of the straits, the 

 variations of the wind, and the inequalities at the bottom. 

 These, though no great object to the philosopher, as their causes 

 are generally local and obvious, are nevertheless of the most 

 material consequence to the mariner ; and without a knowledge 

 of which he could never succeed. It often has happened, that 

 when a ship ha , unknowingly got into one of these, every thing 

 seems to go forward with success, the mariners suppose them- 

 selves every hour approaching their wished-for port, the wind 

 fills their sails, and the ship's prow seems to divide the water ; 

 but, at last, by miserable experience they find that, in.^tead of 

 going forward, they have been all the time receding. The busi. 

 ness of currents therefore, makes a considerable article in navi- 

 gation ; and the direction of their stream, and their rapidity, hni* 

 been carefully set down. This some do by the observation ot 

 the surface of the current ; or by the driving of the troth along 

 the sliore ; or by throwing oirt what is called the log-line, with 

 a buoy made for that purpose, and by the direction and motion 



