76 



A HISTORY OF 



How great, therefore, must have been the 

 amazement of Alexander's soldiers at so 

 strange an appearance ! They who always 

 before had been accustomed only to the 

 scarcely perceptible risings of the Mediter- 

 ranean, or the minute intumescence of the 

 Black Sea, when made at once spectators of 

 a river rising and falling thirty feet in a few 

 hours, must no doubt have felt the most ex- 

 treme awe, and, as we are told, a a mixture of 

 curiosity and apprehension. The tides are 

 also remarkably high on the coast of Malay, 

 in the straits of Sunda, in the Red Sea, at 

 the mouth of the river St. Lawrence, along 

 the coasts of China and Japan, at Panama, and 

 in the gulf of Bengal. The tides of Ton- 

 quin, however, are the most remarkable in 

 the world. In this part there is but one tide, 

 and one ebb, in twenty-four hours ; whereas, 

 as we have said before, in other places there 

 are two. Besides, there, twice in each month 

 there is no tide at all, when the moon is near 

 the equinoctial, the water being for some 

 time quite stagnant. These, with some other 

 odd appearances attending the same phasno- 

 mena, were considered by many as inscruta- 

 ble ; but Sir Isaac Newton, with peculiar sa- 

 gacity, adjudged them to arise from the con- 

 currence of two tides, one from the South 

 Sea, and the other from the Indian Ocean. 

 Of each of these tides there come successive- 

 ly two every day ; two at one time greater, 

 and two at another that are less. The time 

 between the arrival of the two greater, is 

 considered by him as high tide ; the time 

 between the two lesser, as ebb. In short, 

 with this clue, that great mathematician solv- 

 ed every appearance, and so established 

 his theory, as to silence every opposer. 



This fluctuation of the sea from the tides, 

 produces another, and more constant rota- 

 tion of its waters, from the east to the west, 

 in this respect following the course of the 

 moon. This may be considered as one great 

 and general current of the waters of the sea; 

 and although it be not every where distin- 

 guishable, it is nevertheless every where ex- 

 istent, except when opposed by some parti- 

 cular current or eddy, produced by partial 

 and local causes. This tendency of the sea 



* Quintus Curtius. 



towards the west is plainly perceivable in 

 all the great straits of the ocean ; as, for in- 

 stance, in those of Magellan, where the tide 

 running in from the east., rises twenty feei 

 high, and continues flowing six hours; where- 

 as the ebb continues but two hours, and the 

 current is directed to the west This proves 

 that the flux is not equal to the reflux ; and 

 that from both results a motion of the sea 

 westward, which is more powerful during the 

 time of the flux than the reflux. 



But this motion westward has been sensi- 

 bly observed by navigators, 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 was said, in those 

 straits which join one ocean to another. In 

 the straits between the Maldivia islands, in 

 the gulf of Mexico, between Cuba and Ju- 

 catan. In the straits of the gulf of Paria, 

 the motion is so violent, that it hath received 

 the appellation of the Dragon's Mouth. North- 

 ward 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 in- 

 to the ocean on the other. In this manner, 

 therefore, is the sea carried with an unceas- 

 ing circulation round the globe; and, at the 

 same time that its waters are pushed back 

 and forward with the tide, they have thus a 

 progressive current to the west, which though 

 less observa>\e, is not the less real. 



Besides 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 promi- 

 nence of the shores, the narrowness of the 

 straits, the variations of the wind, and the in- 

 equalities 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 conse- 

 quence to the mariner ; and, without a know- 

 ledge of which, he could never succeed. It 

 often has happened, that when a ship has 

 unknowingly got into one of these, every 

 thing seems to go forward with success, the 

 mariners suppose themselves every hour ap- 

 proaching their wished-for port, the wind fills 



